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Title: ENZYMES
Description: These notes give detail explanations about Enzymes The notes are very enriching and are very good for sciences students at the undergraduate and graduate levels and also good for medical students
Description: These notes give detail explanations about Enzymes The notes are very enriching and are very good for sciences students at the undergraduate and graduate levels and also good for medical students
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ENZYMES
Definition: These are organic biological molecules, protein in nature produced by living cells
that speed up the rate of metabolic reactions but are not used up in the course of the reaction
...
Examples of enzymes are: ptyalin or
salivary amylase, pepsin, pancreatic lipase etc
...
Temperature
Enzyme catalyse reaction within a temperature range of 35400C
...
A fall in temperature below this range reduces the rate of
reaction thus enzymes are inactivated and increase in temperature above this range equally
causes a decrease in the rate of reaction thus enzymes are denatured
...
•
pH
This is the degree of acidity and alkalinity of a medium
...
Some act best in extreme acidity while others in extreme alkalinity
...
Example trypsin has an optimum pH of 8 and
pepsin 2
...
Substrate concentration has a similar effect
...
These substances slow down or stop enzyme control reactions
...
•
To Test for the effects of pH on Enzymes
...
1
Procedure
Four test tubes A, B, C and D are used
...
Test tube B contains 5% starch solution plus ¼ teaspoon amylase solution or saliva
...
Test tube D contains starch plus ¼ teaspoon amylase, few millilitres of dilute HCl and test
tube kept at 370C in a water bath
...
Observation
Solution A produces a blueblack colour each that is no change in starch
...
Solution C showed similar results as B but changes occur faster
...
This shows that amylase convert starch to other forms
...
Hence enzymes are specific to pH
...
There are two
types of dentition in animals namely homodont and heterodont dentition
...
•
Heterodont dentition: teeth in the mouth are of different shapes and sizes as in
mammals (man, goat, cow, pig, rabbit etc
...
Mammals have two sets of teeth in their life time
...
There are four types of teeth in the mouth of
mammals each with a specific function
...
The four types of teeth include incisors, canines, premolars and molars
...
Below are the functions of the different tooth
...
Canines: Used in tearing flesh from bones, seizing, piercing and killing prey
...
Structure of the tooth (diagram)
Functions of Parts
...
It protects the teeth from wearing and also
enable the teeth to bite hard substances
...
Pulp cavity: Contain blood vessels and nerves which make the tooth sensitive to internal and
external changes
...
Dental Formula
This is a formula that indicate the number of each type of teeth in the mouth of a given
mammal
...
Dental formula of omnivore such as man:
I2 C1 Pm2 M3 / I2 C1 Pm2 M3 X 2 = 32
Dental formula of carnivore such as dog:
I3 C1 Pm4 M2 / I3 C1 Pm4 M3 X 2 = 42
Dental formula of herbivores such as goat:
I0 C0 Pm3 M3 / I3 C1 Pm2 M3 X 2 = 30
Heterotrophic Nutrition
This is carried out by organism which cannot manufacture their own thus they depend on
other organisms for food
...
Examples of heterotrophs
are bacteria, fungi and animals
...
Holozoic Nutrition
...
It involves processes such as ingestion, digestion, absorption and assimilation
...
This is common in mammals such as man
...
The alimentary canal
It runs from the mouth to the anus
...
This involve processes like ingestion, physical digestion, chemical digestion,
assimilation and egestion
...
Each region is designed to
carry out role in the overall process of digestion and absorption
...
•
Ingestion: This is the taking in of food into the gut or alimentary canal
...
Physical
3
digestion is achieved by the teeth and muscles of the stomach while chemical
digestion is achieve by enzymes
...
•
Assimilation: This is the effective use of end products of digestion to provide energy,
growth, repair and replacement of worn out tissues etc
...
Why digestion is necessary (importance)
...
•
It converts food into soluble and absorbable units for easy uptake by cells of the body
...
•
It enables valuable part of food to be selected and unwanted part eliminated
...
Digestion in the mouth
•
When food is ingested into the mouth, it is chewed
...
•
The chewed food is moistened with saliva to ease swallowing
...
•
Chewed food is roll by the tongue into a bolus
•
The tongue is raised upward and backward to force the bolus to the back of the
mouth for swallowing
...
•
Bolus move by peristalsis along the oesophagus into the stomach
...
•
presence of food in the stomach stimulates the stomach walls to secrete the hormone
gastrin into the blood
...
•
Gastric juice contains dilute solution of HCl and inactive enzymes pepsinogen and
prorenin
...
•
Pepsin hydrolyses protein into smaller polypeptides and peptones while rennin curdles
soluble protein of milk into insoluble casein (thick mass) which is digested by pepsin
...
•
Food is retained in the stomach for about four hours
...
Digestion in the Duodenum
...
•
The gall bladder is stimulated to produce bile which is alkaline and help neutralise
acid on food from the stomach
...
•
Pancreatic juice also contains enzymes pancreatic amylase, pancreatic lipase
trypsinogen and enterokinase
...
•
Pancreatic amylase catalyses break down of starch to maltose
...
•
Pancreatic lipase convert emulsify fat to fatty acid and glycerol which are end product
of fat and oil or lipid
...
Digestion in the Ileum
•
The presence of food stimulates the walls of the ileum to secrete an alkaline liquid
called intestinal juice or succus intericus
...
•
Erepsin convert polypeptides and peptones to amino acid
...
•
The end product of digestion is absorbed into the blood
...
•
The internal surface is greatly increased by the presence of thousands of tiny finger
like projections called villi
...
•
The epithelium of the villi is thin to facilitate diffusion of end product of digestion
...
•
Have many mitochondria to provide energy for uptake of digested food by active
transport
...
•
No chemical digestion takes place in the large intestine
...
•
Symbiotic bacteria synthesis vitamin K which is absorbed into the blood stream
...
•
Faeces remains in the colon for about 36hours and is passed into the rectum for
temporal storage
...
Fate of end product of digestion
...
Glucose
and amino acid are absorbed into the blood capillaries in the villi and transported to the liver
through the hepatic portal vein
...
•
Glucose
...
•
Excess glucose is converted to fat and stored in adipose tissues
...
•
Growth
•
Repair and replacement of worn out tissues
•
Formation of enzymes, hormones and antibodies
6
•
•
Excess is deaminated to form urea which is eliminated by the kidney
...
Fatty acid and glycerol
...
It
makes up 35% of body weight
...
The liver is basically an organ of homeostasis and control many metabolic activities
essentially for maintaining a constant blood composition
...
•
Carbohydrate metabolism that is convert excess glucose to glycogen and vice versa
...
•
Fat metabolism that is convert excess carbohydrate into fat
•
Store fat soluble vitamins such as A, D, E and K and water soluble vitamins B, C
...
•
Stores blood
•
Synthesis red blood cells in foetus or child in the womb
...
•
Produce heat which help to maintain constant body temperature
...
Digestion in Herbivores
...
There are two types of herbivores that is
ruminants and nonruminants
...
Upper jaw have incisors
Bacteria in caecum
Examples as in horse, rabbit
...
•
The goat uses it incisors to cut grass and this is aided by the long flexible tongue
...
The diastema separates freshly cut grass from
chewed grass
...
•
Bacteria produce enzyme cellulase which digest cellulose to disaccharide
...
•
The acids are absorbed by the host which serves as a major source of energy in
respiration
...
•
The partially digested food is passed to the second chamber the reticulum where it is
moulded into cud or pellets
...
This process
is rumination or chewing the cud
...
•
The partially digested food passes through the first three chambers of the gut to reach
the abomasum which correspond to the stomach in man
...
Adaptations of Herbivores to Their Diet
...
•
Have hard horny pad that help in cutting grass
...
•
Premolars and molars have flat and broad surfaces for grinding grass
...
8
•
Have very long intestine for storage and efficient digestion of grass
...
•
Regurgitation ensures food is chewed twice for proper grinding
Autotrophic Nutrition
...
Organisms which carry out this type of nutrition are called autotrophs such as green plants
and bacteria
...
Differences between Autotrophic and Heterotrophic Nutrition
Autotrophic Nutrition
Carried out by green plant and some bacteria
Two types photosynthesis and chemosynthesis
•
Heterotrophic Nutrition
Carried out by animals, fungi, some
bacteria
Five types saprophytic, parasitic,
mutualism, commensalism and holozoic
nutrition
Chemosynthesis
This is the process by which some bacteria manufacture complex organic food substances
such as carbohydrate, lipid from simple inorganic substances such as carbon dioxide and
water with energy from the oxidation of chemicals
...
The equation below summarises this process
...
•
The light phase or photolysis
...
Water molecule is broken down into hydroxide and
hydrogen ions
...
Light energy is trapped by the pigment
chlorophyll
...
Energy is stored in chemical form called ATP (adenosine
triphosphate) which is used in the dark reaction phase
...
During this phase, H+ from the light phase are used to reduce CO2 forming glucose
(carbohydrate)
...
Differences between photosynthesis and chemosynthesis
Chemosynthesis
Energy from the oxidation of chemicals
Occur in one phase
Carried out by bacteria
Photosynthesis
Energy from the sun
Occur in two phases
Carried out by green plants
Site of Photosynthesis
The main organs of photosynthesis are the leaves
...
Chloroplast are organelles containing the green pigment chlorophyll which help to trap
sunlight energy during the process of photosynthesis
...
Functions of Parts of the Leaf
...
Stomata: For gaseous exchange
Guard cell: Determine size of the stomata
...
It also
prevents excessive water loss and damage by parasitic fungi
...
Mesophyll cells
10
•
Palisade mesophyll cells: Cells are columnshaped thin wall cells with numerous
chloroplast for maximum absorption of sunlight energy
...
Adaptation of the Leaf to the Process of Photosynthesis
...
•
Have large intercellular air spaces in the mesophyll to facilitate gaseous exchange
•
Have numerous stomata on the lower epidermis for gaseous exchange
•
Have numerous chloroplast in the palisade mesophyll cells for maximum absorption
of sunlight
...
•
The cuticle is transparent for the penetration of sunlight energy needed for
photosynthesis
•
The cuticle is waxy and waterproof to prevent desiccation of the mesophyll cells
...
How Photosynthesis Takes Place in a Green Leaf
...
•
This process requires CO2, H2O and energy
...
•
CO2 from the atmosphere diffuses through the stomata and intercellular air spaces
into the mesophyll cells
...
•
CO2 is reduced by hydrogen atoms to sugars such as glucose
...
•
Reduction is facilitated by energy (ATP) and enzymes
...
11
•
The O2 diffuse out of the mesophyll cells into the intercellular air spaces, through the
stomata to the atmosphere
...
End products of photosynthesis are principally glucose and O2
...
•
Fate of Glucose
•
It is converted to starch and stored in the leaf
...
•
It broken down to release energy during respiration
...
•
It is incorporated to nitrogen and sulphur to form proteins necessary for
growth, repair and replacement of worn out tissues, formation of enzymes
and hormones
...
•
It is converted to pigments to give variety of colours to leaves, flowers and
other plants parts
...
Factors Affecting the Rate of Photosynthesis
...
Low or high
temperature will inactivate or denature enzymes thus hindering the process
...
Decrease
in temperature equally decrease the rate of photosynthesis
...
Increase in light
intensity increases the rate of photosynthesis because stomata will be widely open for
gaseous exchange
...
•
Water: It provide hydrogen ions used in the reduction of CO2
...
•
Carbon dioxide concentration: CO2 is needed in the reduction process for the
formation of carbohydrate during photosynthesis
...
If CO2 concentration fall the rate of
photosynthesis also falls
...
This is obtained from the soil as magnesium salt
...
Also nitrates and
phosphates are needed in the synthesis of proteins, their deficiency hinder the rate of
photosynthesis
...
•
Provide food to plants and other living organisms like man
•
Enrich the atmosphere with oxygen needed for aerobic respiration
•
Help in the circulation of carbon in nature
•
Control the amount of carbon in the atmosphere thus reducing global warming
Experiments on photosynthesis
•
To Test for Starch in a Green Leaf
Requirements: a green leaf, iodine solution, white tile, test tubes, alcohol, hot water
bath, beaker
...
•
This is to make sure that all starch and starch reserves are used up
...
Hot water also remove alcohol on
the leaf
•
The decolourised leaf is placed on a white tile and iodine solution poured on its
surface
Observation
...
A blueblack colour indicates the presence of starch
...
A potted plant with variegated leaves, materials to test for starch in a leaf
...
•
The potted plant is then expose to sunlight for six hours
...
Observation
...
Conclusion
...
This shows that
starch is necessary for photosynthesis
...
A potted plant, aluminium foil or black carbon paper, paper clips and
materials to test for starch
...
•
The potted plant is screened from sunlight for 48 hours
•
A black carbon paper is used to cover portion of one of its leaf
...
•
Portion of the leaf that is expose to sunlight serves as the test experiment while
portion covered as the control
...
Observation
...
Conclusion
...
•
To Show that CO2 is Necessary for Photosynthesis
...
Polythene bag, dish of KOH or NaOH, iodine solution, water, two potted
plant, two transparent bell jar
...
•
The two potted plant are screened from light for 48hrs and then placed in bell jar A
and B
•
The pots containing the plants are surrounded with polythene bag to prevent CO2
from respiring soil organism
...
Observation
...
Conclusion
...
CO2 and all other factors were present in
bell jar B thus starch was formed
...
•
To Show that O2 is given off During the Process of Photosynthesis
...
Aquatic green plant egg Elodea sp, test tube, funnel, beaker, support and
glowing splint
...
•
The setup is as above that is test experiment
...
•
NaHCO3 solution is added to water to release CO2 needed for photosynthesis to
take place
•
When sufficient gas has collected, the test tube is removed and a glowing splint
inserted
...
When the glowing splint is inserted into test tube from the test
experiment, it rekindles a glowing splint or burst into flame while that from control
experiment did not burst into flame
...
This shows that gas release during photosynthesis is oxygen
Mineral Nutrition of Plants and Animals
...
Also heterotrophic organisms like animals need some minerals to supplement their organic
food or diet
...
These minerals
include essential elements and trace elements
...
The major essential elements of life are: C, H, O,
N, S, P, K, Na, Mg, Ca and Cl
...
Examples
are Fe, Mn, Cu, Zn, boron, iodine, fluorine, and cobalt
...
Essential elements form macronutrients
15
while trace elements form micronutrients
...
Some Minerals and Deficiency Diseases in Plants
element
Nitrogen
Form absorb
Nitrates, NH4
Mg
Ca
Fe
Mg 2+
Ca2+
Cu
Zn
Function
Protein synthesis, nucleic acid,
chlorophyll
Component of chlorophyll
Formation of cell wall
Synthesis of chlorophyll
Electron carrier in
photosynthesis
Anaerobic respiration
Deficiency disease
Stunted growth, strong
chlorosis of older leaves
chlorosis
Stunted growth
Strong chlorosis in
young leaves
Dieback of shoot
Mottle leaf of citrus or
sickle leaf of cocoa
Some Minerals and Deficiency Diseases in Animals
element
Nitrogen
Ca
Fe
Iodine
Fluorine
Food
Meat, fish,
milk
Milk, hard
water
Liver, red
meat, spinach
Seafood, salt
Drinking
water, milk
Function
Protein synthesis, nucleic acid,
coenzymes
...
16
Poor skeletal growth
leading to rickets
Anaemia
Respiration
...
This is the chemical breakdown or oxidation of food in the presence or absence of
oxygen to release energy
...
When it
occurs in the presence of oxygen it is called aerobic respiration while in the absence of
oxygen it is called anaerobic respiration
...
They are broken down
gradually in a series of enzyme controlled reactions with the release of small amount of
energy some of which is stored in the form of ATP and the rest lost as heat
...
Aerobic Respiration
...
It can be summarised by the equation below
C6H12O6 + O2
enzymes
CO2 + H2O + 2827KJ Energy
It occurs in two stages that is partly in the cytoplasm in the absence of oxygen called
glycolysis
...
Second stage in the mitochondria where pyruvate is
completely broken down into CO2 and H2O with the release of much energy in the form of
ATP
...
This is the chemical break down of glucose or fat in the absence of
oxygen to release energy
...
C6H12O6
enzymes
CO2 + C2H5OH + 210KJ Energy (in plants)
C6H12O6
enzymes
lactic acid +210 KJ Energy (in animals)
In animals such as man, it occurs in muscles during vigorous or stannous physical exercise
...
This is a supplement to aerobic respiration to satisfy the energy need of
the body during exercise
...
The lactic acid is slowly converted to pyruvate for further break down
or pyruvate to glucose by reverse glycolysis
...
Aerobic Respiration
Anaerobic Respiration
Require O2
Does not require O2
Food is completely oxidised
Food is partially oxidised
Occur in the mitochondria
Occur in the cytoplasm
Occur in higher organisms like man or Occur in lower organisms like bacteria
animals
Biproducts are not toxic CO2 and H2O
Biproducts are more toxic; ethanol and lactic
acid
Involve breathing and tissue respiration
Involve only tissue respiration
...
Similar in plants and animals
Different in plants and animals
17
H/W: 1
...
What are the similarities between aerobic and anaerobic respiration, internal and external
respiration?
External respiration or Ventilation
...
Examples are lungs in airbreathing vertebrates like man and is
assisted by respiratory movements (e
...
breathing)
...
Gills in fish etc
...
Properties of the Lungs that make it a Good Respiratory Surface
...
•
The alveoli are protected from physical and chemical damage
•
The alveoli are accessible for effective internal and external respiration
...
Photosynthesis
Occur only during the day when there is
sunlight
Carried out only by green plant
Food
substances
are
manufacture
(anabolism)
Uses simple inorganic substances like CO2
and H2O
Energy is needed trapped from sunlight
Oxygen is release as a biproduct
Lead to an increase in weight
Respiration
Occur at all the times
Carried out by all living cells
Food substances are broken down
(catabolism)
Uses organic substances like carbohydrates
and fats
Energy is release as an end product
Oxygen is used up
Lead to a decrease in weight
18
Gaseous Exchange in Some Organisms
...
It is a unicellular organism thus have a large surface area to volume ratio
...
Oxygen in surrounding water diffuse into
the cytoplasm where it is used for tissue respiration while CO2 produced during tissue
respiration diffuse to the surrounding water through the cell surface membrane
...
Gaseous Exchange in Flowering Plants
...
Stomata open only during the day and closes at night
...
Air enter intercellular space and oxygen from it diffuse into the mesophyll cells where
it is used for tissue respiration
...
(review)
Respiration in Mammals such as Man
...
It consists of a pair of lungs found next to the heart in the thoracic cavity
...
The lungs and heart
are protected by 12 pair of ribs
...
Air enters the respiratory system through a pair of nostrils each having hairs which
help to trap dust particles and filter them out of the system
...
Air passes from nasal cavity through
the pharynx and into the trachea
...
Trachea branch into bronchi,
bronchus into bronchioles and bronchioles into alveolar duct which enter alveolar sac
with many alveoli
...
The trapped particles are carried to the back of the mouth and
swallowed
...
19
Mechanism of Breathing or Ventilation
...
The mechanism of the movement varies with the
species
...
Contraction of these muscles lowers the diaphragm and raises
the ribs, so that the lungs expand and air is drawn in (inspiration)
...
Inspiration (breathing in)
...
•
At the same time the diaphragm muscle contract making the diaphragm to flatten
•
This increases the volume of the thorax and thus the lungs
•
Pressure in the lungs reduce less than atmospheric pressure
•
Reduction in pressure enable air to enter the lungs inflating the alveoli until air
pressure in the lungs is the same with atmospheric pressure
...
•
This is an active process thus require energy
...
•
During this, the intercostal muscles relax and rib cage move downward and
inward
...
•
This is a passive process assisted by elastic recoil of the lungs, respiratory muscles
and weight of the rib cage
...
Inspired air
Contain more O2 (21%)
Expired air
Contain less O2 (16%)
Contain less CO2 (0
...
Gaseous exchange in the Alveolus
...
•
Air contain a high concentration of O2 and a low concentration of CO2
...
•
O2 concentration of blood in the capillaries surrounding the alveolus is lower than in
the alveolar cavity
•
O2 thus diffuses through the epithelium of the alveolus, thin capillary wall into blood
in the capillaries where it is in low concentration
...
Diagram
...
These are terms used to describe the volume of air
associated with breathing
...
This is the total volume of air the lungs can hold
...
5litres in males and 4
...
This is the volume of air entering and leaving the lungs during normal or
quiet breathing
...
5litres
...
This is the maximum volume of air that can be exchanged during
forced inspiration and expiration
...
This is the increase in volume to completely fill the lungs
during forced inspiration
...
This is the decrease in volume to empty the lungs during forced
expiration
...
This is the volume of air that must always remain in the lungs no matter
how hard breathing out is done
...
2litres
...
Experiment on Respiration
...
Aim
...
Requirements
...
Diagram
...
•
Germinating bean seeds are moistened and placed in thermos flask labelled A
while dry bean seeds are placed in thermos flask labelled B
...
•
Thermos flasks are used to conserve heat and to prevent escape to the outside by
conduction or radiation
...
•
A thermometer is inserted into the thermos flasks through the cotton wool so that
the bulb should well in contact the seeds for accurate recording of temperature
...
•
The setup is left for about six hours
...
•
After six hours, an increase in temperature is observed in thermos flask A
containing germinating seeds
...
Conclusion
...
22
An experiment to show that CO2 is produced by mammals during respiration
...
Aim
...
Requirement
...
Diagram
...
•
Glass bottle A is half filled with caustic soda while glass bottle B and D with lime
water
...
•
Each vessel is fitted with a twohole rubber stopper carrying bent glass tubes
...
•
Lime water in both glass bottles B and D should be clear at the start of the
experiment
...
•
A similar experiment is setup with a death sterilised rat in place of a life rat to
serve as the control experiment
...
Any traces of CO2 are
removed by lime water in B
...
•
As air passes through respiratory bottle C, the respiring mammal absorb O2 for
aerobic respiration and CO2 and water vapour are given off
...
•
The clear lime water in D turns milky as air from respiring mammal passes
through it
...
•
Water vapour condenses on the inner surface of the respiratory bottle
...
Conclusion
...
The importance of respiration
•
Produces energy used for biological work
•
The water produce during respiration help to increase the body’s water content
•
The CO2 released during respiration is used for photosynthesis by green plants
23
•
The heat produced during respiration helps to keep the body warm
...
Definition
...
from the cells of the body which if allowed to accumulate will poison the cells of the body
and may lead to the death of the organism
...
Excretion is necessary because
•
It prevents toxic or poisonous metabolic waste products such as urea, CO2 from
accumulating which may harm body cells
...
both plants and animals have special
excretory organs for handling these waste products
...
The main excretory products in plants origin and method of elimination
...
Stored in leaves, fruits, and petals
...
Water
Obtained from the soil
and from aerobic
respiration
Mineral salts Obtained from the soil
Glycosides
and tanins
Glucose metabolism
Excretion in mammals such as man
...
Excretory organ
Skin
Excretory product
...
• Excretory products origin and methods of elimination
...
•
Kidney
...
•
Ureter
...
25
•
Bladder
...
Carries urine from the bladder to the outside
...
Regulate passage of urine from the bladder to the outside
...
Carries oxygenated blood to the kidneys
•
Renal vein
...
The kidney
...
The
cortex is covered by a tough capsule and contain glomeruli just visible to the naked eye
...
The basic unit of structure of the kidney is the nephron
...
(Pyramid, renal artery and vein)
How the kidney function in excretion?
•
Excretion in the kidney take place in the nephrons
...
•
Large substances such as such as blood cells, blood proteins remain in the glomerulus
...
•
As glomerular filtrate moves down the kidney tubules useful substances are
reabsorbed in a process called selective reabsorption
...
This make the glomerular filtrate more concentrated
•
At the descending limb of the loop of henle, there is reabsorption of water
...
26
•
At the distal convoluted tubule, more salt and water are reabsorbed
...
•
At the collecting duct more water is reabsorbed depending on the osmotic
concentration of the body
...
•
Fluid that remain in the collecting duct is called urine which is made up of
nitrogenous waste, some water and salt
...
(diagram)
Osmoregulation
...
This is necessary to
prevent water moving in and out of cells by osmosis
...
•
The osmoreceptors in the hypothalamus are stimulated and impulses send to the
pituitary gland
...
•
ADH brings about permeability of the kidney tubules at the distal convoluted tubule
and collecting duct to water
...
In this
situation urine produce is usually less in quantity and coloured
...
•
When the body fluid is less concentrated due to much water drunk or less salt
consume, the osmoreceptors are less stimulated and little or no ADH is secreted
...
Thus less water is reabsorbed from the glomerular filtrate into the
blood stream
...
In this situation very
dilute and colourless urine is produced
...
Failure to produce enough ADH lead to a condition known as diabetes insipidus in
which large quantity dilute urine is produced called (diuresis)
...
This is the largest organ and forms the outer covering of the human body
...
27
Structure
...
•
The cornin fied layer
...
Cells are living tough and flexible and also play a role in protection
•
Malpighian layer
...
Also secrete pigment melanin which prevent penetration of
UV radiation and skin burn
...
Secrete sebum which make the hair water proof and keep the skin
supple
...
•
Sweat gland
...
•
Sweat duct
...
Acts as food reserve during starvation, shock absorber, insulate the
body from cold
...
Trap and provide an insulating layer of air against heat loss by the body
•
Erector muscle
...
•
Pacinian corpuscle
...
•
Meisners corpuscle
...
•
Free nerves endings
...
Functions of the skin
...
•
The cornified layer is tough and prevent the skin from the physical and chemical
damages
...
•
Keratin a fibrous protein synthesis from the skin makes it water proof preventing
dryness
•
Subcutaneous fatty layer acts as a shock absorber
•
Melanin pigment secreted absorbs and dispersed excess UV radiation from the sun
thus prevent the skin burn or damages
...
The skin eliminates sweat containing excess water, salt, urea and lactic acid
...
28
Vitamin synthesis
...
Deficiency of vitamin D in children causes rickets and osteomalacia
(weak bones)
...
Reception of stimuli
...
The paccinian corpuscle is sensitive to pressure and
touch while the meisners corpuscle is sensitive to pain
...
Storage organ
...
Temperature control
...
If the temperature of the body is to remain
constant over a given period of time, then heat gain by the body must be equals to heat loss
by the body
...
•
Decrease sweat production which reduces heat loss by evaporation
...
The arterioles which supply blood to the surface capillaries
reduce in diameter or constrict
...
Blood thus passes through shunt vessels deeper in the
skin
...
•
Hairs stand erect
...
Erect hairs trap an insulating layer of air above the skin
...
•
Shivering
...
•
There is equally increase in metabolic activities which generate heat in the body
...
Sweating
...
Evaporation of
sweat absorbs heat from the body thus reducing body temperature
...
The arterioles under the skin open wider or dilate for more blood supply
to the capillary network (superficial blood capillaries) under the skin
...
Hairs lie flat
...
In this position
they offer least resistance to heat loss by radiation and convection
...
Transport in Plants and Animals
...
Transport can
be short distance such as cytoplasmic streaming, alveolus to blood capillaries or long distance
such as from roots of plants to leaves, ileum to brain etc
...
There is no need of a complicated transport system
...
These organisms
have a large surface area to volume ratio
...
Therefore, specialised longdistance transport
system which can move substances more rapidly becomes necessary
...
A vascular system is one
which has tubes which are full of fluid being transported from one place to another
...
The importance of a transport system
...
Transport in flowering plants
...
They have the vascular
system made up of xylem and phloem which assist in movement of substances
...
Water and mineral salts are absorbed from the soil and transported through the xylems
to the leaves of the plant where food is manufactured
...
Arrangement of vascular tissues in dicot and monocot
...
•
Epidermis
...
•
Xylems
...
Provide
mechanical support and prevent rotting of plant tissues
...
Transport manufactured food from the leaves to storage organs and other
parts of the plant
...
Divide to form new xylem and phloem
...
Stores food
...
•
Water and mineral salt are absorbed from the soil by the root hairs through the
process of osmosis and active transport
...
•
The root hairs are many, thin and lack cuticle and also facilitating uptake of water and
mineral salt
...
Xylem vessels are non
living
...
•
Root pressure is due to accumulation of water in the roots hair cells as a result of
continuous uptake from the soil
...
•
Conduction of water beyond this point to higher branches and leaves need a pulling
force exerted from above
...
•
The continuous flow of water from the roots to the leaves forms a transpiration stream
or pull which depends on the rate of transpiration
...
•
These forces are assisted by the fine nature of xylem (capillarity), cohesion and
adhesive properties of water molecules
...
•
Mineral salt is transported alongside with water
...
•
Glucose is manufactured in the leaves of plants during the day and converted into
insoluble starch and stored in the leaves
...
•
The transport of organic substances in plant is called translocation
...
•
Phloem tissues are living and consist of elongated sieve element placed end to end to
form sieve tubes
...
Amino acid and glucose move against their concentration gradient
...
Experiment to show that phloem tissues transport manufactured food
...
A potted plant and a sharp knife
...
Procedure
...
This process is called girdling or ringing
...
The setup is left for about one month
...
Leaves and branches remained fresh while portion above the cut or ringed region
swell
...
Food
substances manufactured from the leaves are transported downward through the phloem
...
Conclusion
...
An Experiment to show that xylem tissues conducts water upward from the roots to the
leaves
...
To show that xylem tissues conducts water upward from the roots to the leaves
...
A potted plant such as balsam plant, a sharp knife, beaker water and red dye
...
Procedure
...
•
The roots of the plant are placed in beaker containing a solution of red dye
•
The setup is left for three hours
•
At the end of this time the plant is removed from the solution, washed in tap water
and the cross section of the root, stem and leaves are observed under the microscope
...
The cross section after observation under the microscope shows that the xylem
stands significant because they are stained by the red dye
...
Conclusion
...
32
Transpiration
...
This is the loss of water in the form of water vapour from the surfaces or aerial
part of the plant such as stem, branches and leaves to the atmosphere
...
The loss of water by plants in the form of liquid is called
sudation or guttation
...
About 98% is loss through the process of transpiration
...
•
Light
...
The stomata open widely during the day allowing more water
vapour to diffuse into the atmosphere
...
•
Wind
...
Contrary when the air around the leaves of a
plants are in constant motion, water vapour around the leaves are carried away before
saturation giving room for more to evaporate from the leaves hence increasing the rate
of transpiration
...
When the atmosphere is fully saturated with water vapour there is no
possibility of more vapour moving into it
...
The difference in the water content of the plant and that of the atmosphere
affects the rate of transpiration
...
•
Temperature
...
When there is an increase
in temperature, the capacity of air to hold water increases
...
At low
temperature the atmosphere becomes saturated with water vapour thus a decrease in
the rate of transpiration
...
The amount of water vapour lost by
transpiration also depends on the amount of soil water available to the plant
...
The opposite takes place when an excess of soil
water is available to the plant
...
•
Help in the uptake of water and mineral salt from the soil by plants
•
Help in the ascent of water to the leaves of very tall plants
•
Help the plant to get rid of excess water
•
Help to cools the plants because heat is lost as water is converted to water vapour
...
33
Adaptations of plants to prevent water loss
•
Leaf fall that is some plants shed their leaves during the dry season
•
Leaves are reduced to scales, pines or thorns
•
Possession of thick cuticle
•
Possession of sunken stomata
•
Reduction in the number of stomata
•
Rolling of leaves
•
Hairs on the under surface of the leaves to prevent water loss
•
Stomata close during the day and open only at night to prevent excess water loss
...
1
...
Requirementspotted plant, polythene bag, Vaseline, glass plate and bell jar
...
Place the potted plant on a glass plate
...
This prevents loss of water from the soil surface by evaporation
...
This serves as
the test experiment
...
Both setups are
placed near an open window for two hours
...
No water is seen in the inner surface of bell jar without plant
(control)
...
Transpiration takes place in plants
...
The potometer experiment (measuring the rate of water uptake by a leafy shoot)
Requirements
...
Diagram
Procedure
...
This is to ensure that no air bubbles enter the xylem vessels
...
•
The shoot is inserted through the hole in the cork of a potometer
•
Vaseline is smeared around part of the shoot in contact with the cork to make it
airtight
34
•
The tap of the reservoir is opened to fill the graduated capillary tube with water
...
As water evaporates from the leaves of the plant more is drown from the potometer
...
The air bubble is
observed to move with water column
...
A number of readings should be taken and the mean
calculated to gives the rate of transpiration
...
Conclusion
...
1
...
A potted plant, water, polythene bag, glass plates and an empty bucket
...
•
A potted plant is well irrigated and the pot and soil surface are covered with a
waterproof bag
...
•
Both setup is left in light for two hours
...
Drops of liquids are observed on the inner surface of the bell jar containing the potted
plant but not in the control
...
Conclusion
...
Diagram water drops, plant,
bell jar, polythene bag, glass plate smeared with Vaseline and control
...
Transport in animals (Man)
...
These
cells, tissues and organs need useful substances such as O2 and soluble products of digestion
and also need to get rid of waste products
...
These problems are solved in part by the development of a transport system
...
The circulatory system is a system of hollow tubes called
vessels containing a fluid called blood which is circulated by means of a pump called the
heart
...
Translocation
Process is not continuous
Heart is not involved
Occurs in both plants and animals
Materials move directly to site needing
them
Bidirectional movement of materials is
possible
Circulation
Process is continuous
Heart is involved
Occurs only in animals
Materials move round the body supplying need
of cells
Different vessel transport to and from the heart
Composition of Blood
...
It is
contained within a blood vascular system and in vertebrates is circulated by means of
contractions of the heart
...
In addition, blood carries hormones and also acts as a defence system
...
Blood cells include RBC, WBC and platelets
...
Blood plasma
...
e
...
It consists of
water containing a large number of dissolved substances, including proteins, salts
(especially sodium and potassium chlorides and bicarbonates), food materials (glucose,
amino acids and fats), hormones, vitamins, and excretory materials
...
Blood cell (blood corpuscle)
...
These include red blood cells (erythrocyte), white blood cells (leucocyte) and
platelets
...
They are the most numerous and contain the red pigment haemoglobin which is
responsible for oxygen transport and give blood it red colour
...
Mammalian
erythrocytes are discshaped and lack a nucleus while those of other vertebrates are
oval and nucleated
...
5
and 5
...
They are shortlived and can with a life span of
about four months
...
Diagram
•
36
•
Platelet (thrombocyte)
...
They play an
important role in blood clotting, releasing chemicals in response to local tissue
damage, which causes a chain of events leading to the formation of a plug at the site
of the damage, thus preventing further blood loss
...
Diagram
...
•
This is the production of a mass of semisolid material at the site of an injury that
closes the wound, helping to prevent further blood loss and bacterial invasion
...
•
Damage to tissue or a wound triggers the release of thromboplastin from the
breakdown of platelets on exposure to air in the blood stream
...
•
Thrombin catalyses the formation of the insoluble protein fibrin from soluble
fibrinogen and the fibrin forms a fibrous network in which blood cells become
enmeshed, producing a clot
...
The scab later falls off leaving a scar
...
Wounded tissues (platelets) –thromboplastin (enzyme) prothrombin (calcium ions,
enzyme) thrombin (soluble fibrinogen insoluble fibrin)
...
Many types
Less numerous
...
Blood has three main functions namely transport, defence and homeostasis
...
•
Transport respiratory gases from the lungs to the tissues and vice versa
...
•
Transport waste products of metabolism from the tissues to their respective sites
or organs for elimination
•
Transport wbc such as antibodies to site of infection
•
Transport heat from muscles and liver to all parts of the body for temperature
regulation
...
Defence
...
•
WBC produce antibodies such as lymphocytes to fight against foreign particles
•
Phagocytic WBC engulf and digest foreign particles (pathogens)
•
Some WBC soften the effects of toxins at site of infection
...
•
Transport substances to the cells while removing its waste thus maintaining a
constant internal environment around the cell
...
Blood vessels
...
There are three main types of blood vessels in the human
circulatory system namely arteries, veins and capillaries
...
They are fairly wide and made up of three muscular layers
...
They transport oxygenated blood away from the heart under high pressure except the
pulmonary artery which transport deoxygenated blood from the heart to the lungs and
the umbilical artery which transport deoxygenated blood from the foetus to the
placenta
...
Arteries
divide into smaller vessels called arterioles
...
•
Capillaries
...
They
are not muscular and lack elastic tissues
...
They form a dense network and every cell in the body in
close contact with them
...
Capillaries unite to form venules which also unit to form
veins
...
The walls of capillaries are impermeable to RBC and plasma protein such as
fibrinogen
...
They return blood to the heart
...
They have valves to prevent the back flow of blood
...
Veins are more superficially located than arteries
...
Differences between arteries veins and capillaries
...
Blood flow is continuous
Located between arteries and
veins
Blood flow is very slow
Mixed
...
This is a hollow muscular organ which by means of regular contractions, pumps blood
through the circulatory system
...
Cardiac muscles are smooth muscles which contract without
fatigue
...
The right and left side are completely separated by a muscular wall
called septum
...
Mammals have a fourchambered heart consisting of two atria and two
ventricles
...
The walls of the left
ventricle are thicker than the walls of the right ventricle because it is involve in systemic
circulation (pumps blood to the whole body) while the right is involve in pulmonary
circulation
...
There are also semilunar valves between the ventricles and
arteries to prevent backflow of blood into the ventricles
...
An average adult human heart
contracts about 70 times per minute
...
That is deoxygenated blood
enters the right auricle through the vena cava while oxygenated blood enters the left
auricle through the pulmonary vein
...
•
When the right auricle contracts, deoxygenated blood is forced through the tricuspid
valve into the right ventricle
•
When the left auricle contracts, oxygenated blood is forced through the bicuspid valve
into the left ventricle
...
•
The left and right ventricles contract simultaneously
...
•
When the left ventricle contracts, oxygenated blood is pumped through the aorta to all
the systems/tissues of the body
...
How the heart works (working of the heart)?
The main function of the heart is to pump blood around the body
...
The contraction of
heart chambers is called systole, while the relaxation of the heart chambers is called diastole
...
Atrial systole last for 0
...
3 seconds
...
Thus heartbeats last for 0
...
Systole:
•
This occur independently with atrial systole occurring before ventricular systole
...
•
When the right auricle contracts, deoxygenated blood is forced through the tricuspid
valve into the right ventricle while when the left auricle contracts, oxygenated blood
is forced through the bicuspid valve into the left ventricle
...
When this
occur, pressure in the ventricles rises and closes the atrioventricular valves (bicuspid
and tricuspid valves) preventing blood from returning to the auricles
...
•
High pressure developed in the ventricles force open the semilunar valves of the aorta
and the pulmonary artery and blood enters these vessels
...
Diastole:
•
Atrial and ventricular diastole occurs simultaneously during which the whole heart is
at rest
...
•
Deoxygenated blood enters the right auricle through the vena cava while oxygenated
blood enters the left auricle through the pulmonary vein
...
•
Pressure in the auricles rises greater than in the relaxed ventricles and the valves are
pushed open
...
•
This tend to force some of the blood back towards the ventricles and this closes the
semilunar valves of the aorta and the pulmonary artery
...
NB
Heartbeat: This is the rhythmic contraction and relaxation of heart muscles
...
This pressure is greatest during the contraction of the ventricles of the heart which
forces blood into the arterial system
...
Blood pressure is measured in millimetres of mercury using
an instrument called a sphygmomanometer
...
Abnormally high blood pressure (hypertension) may be associated with disease or it may
occur without an apparent cause
...
When the BP is lower than normal,
it leads to a condition called hypotension
...
Pulse: A series of waves of dilation that pass along the arteries, caused by pressure of blood
pumped from the heart through contractions of the left ventricle
...
g
...
Cardiac output: The volume of blood pumped per minute by each ventricle, which is also the
total blood flow through the pulmonary circuit
...
This is determined by heart rate (number of beats per minute) and stroke volume
(amount of blood pumped by each ventricle in a single contraction)
...
•
Age: men who are 45 years and older and women of 55 years and older are more
likely to have heart attack than younger men and women
...
Smoking also
increases the risk of deadly blood clots forming and causing a heart attack
...
High BP that occurs with obesity smoking, high cholesterol or
diabetes increases your risk even more
...
•
Obesity: this raises the risk heart diseases because it is associated with high blood
cholesterol levels
...
•
Lack of physical activity: an inactive lifestyle contributes to high blood cholesterol
levels and obesity
...
Exercise is
also beneficial in lowering high BP
...
•
Sex: generally, men have a higher risk than women of developing coronary heart
diseases in the middle age
...
How heart attack could be prevented
...
•
Achieve and maintain a healthy weight
•
Control diabetes
•
Avoid smoking: smokers have twice the risk to heart attack than nonsmokers
...
This is fluid formed from blood and it bath or surrounds the cells of the body
...
Formation of tissue fluid
...
•
Since capillary walls are thin, this make them permeable to substances of relatively
small molecular size
...
•
The movements of water, oxygen and other substance like glucose from capillaries to
tissue fluid or from tissue fluid into blood capillaries depends on the pressure of blood
in the capillaries
...
43
•
The fluid that is expelled has a similar composition to blood plasma containing
dissolve glucose, amino acid and salt but with lower concentration of plasma protein
...
•
This released fluid penetrates between the spaces of cells of all living tissues and is
called tissue fluid
...
•
Capillaries offer resistance to blood flow thus by the time blood reaches the venous
end of the capillary, pressure is low
...
•
Metabolites like glucose that would have made the tissue fluid concentrated is
constantly being taken up by tissues for respiration
...
Blood serum
...
Serum containing a specific antibody
or antitoxin may be used in the treatment or prevention of certain infections
...
g
...
The Human Circulatory System
This is a system that ensures circular flow of blood through an extensive network of blood
vessels and controlled by the pumping action of the heart
...
In other animals like insect’s mollusc, vessels are
absent and blood flow in sinuses (haemocoel) this system is described as open circulatory
system
...
Pulmonary circulation is the
flow of blood from the heart to the lungs for oxygenation and back to the heart while
systemic circulation is the flow of blood from the heart to the whole body (tissues, organs)
and back to the heart
...
Double circulation is
advantageous because there is no mixing of oxygenated and deoxygenated blood
Lymphatic system
...
Accumulation of excess tissue fluid makes
the body swell (oedema)
...
This begins when excess tissue fluid enters
the lymphatic capillaries where it is known as lymph
...
Fats are found in
suspension and their presence varies with food intake
...
Oneway valves prevent
back flow of lymph
...
The lymph eventually enters the bloodstream near
the heart
...
In humans,
major lymph nodes occur in the neck, under the arms, and in the groin
...
Functions of the lymphatic system
...
•
Transport metabolic waste to the heart to be pumped to excretory organs
...
Blood
Red in colour
Has less lymphocytes
Has RBC
Has oxygen
Have less waste materials
Moves to and from the heart
Moves due to pumping action of the
heart
Have platelets
Has more digested food (protein)
Contained within blood vessels
Lymph
Milky white in colour
Has more lymphocyte
Lack RBC
Lack oxygen
Have more waste materials
Moves from tissues to the heart
Moves due to contraction of muscles and lymphatic
vessels
Lack platelets
Has less digested food (protein)
Contained within lymphatic vessels
Blood groups
...
Blood of one group contains antibodies in the serum that react against the antigens on the
cells of other groups
...
In man,
the two most important blood group systems are the ABO system and the system involving
the Rhesus factor
...
Alleles A and B are dominant over O and codominant to each other
resulting to four blood groups that is A, B, AB and O
...
Blood group B has antigen B on RBC but antibody an in plasma
Blood group AB has antigen A and B on RBC but no antibody in plasma
Blood group O has no antigen but antibody a and b
...
If it
happens agglutination or clumping of RBC will occur
...
This is the process of transferring blood from one person into the circulatory system of
another intravenously (within a vein)
...
Allogenic blood transfusion is when the patient
is transfused with blood donated by someone else (unknown volunteer donor)
...
•
An individual of blood group A can only receive blood from another person of blood
group A and O but can donate to persons of blood group A and AB
•
An individual of blood group B can receive from another of blood group B and O but
can donate to persons of blood groups B and AB
•
An individual of blood group AB can receive blood from all blood groups but can
only donate to individuals of blood group AB
•
An individual of blood group O can only receive blood from another of the same
blood group (O) but can donate to persons of the other blood groups (A, B, AB and
O)
...
Donor/recipient
A
B
AB
O
A
√
x
√
x
B
x
√
√
x
AB
x
x
√
x
Blood Typing or testing
...
Both sera
are placed on slides and labelled (sketch)
...
•
If agglutination occurs in A and not in B then the individual is of blood group B
...
•
If agglutination occurs in both sera then the individual is of blood group AB
•
If no agglutination occurs in both sera, then the individual is of blood group O
When blood transfusion is necessary
...
•
During severe illnesses
...
Precautions to be taken before transfusing blood
...
•
Blood should be screened or tested for infections such as HIV, hepatitis B and C,
syphilis etc
...
This
determine ABO and rhesus status
•
The recipient blood is cross matched to fine blood from a donor that the recipient’s
body will accept
...
•
The portion of skin above the vein to be punched should be properly disinfected with
alcohol
...
•
Anaemia: Shortage of RBC
•
Arteriosclerosis: Degeneration of blood vessels due to the narrowing of the lining
of the walls of an artery causing blood clot to form (thrombosis)
...
A rare genetic disease that
occur mostly in males
47
•
Leukaemia: Also known as blood cancer where the number of WBC increases
greatly
...
There is internal bleeding and rise in infections
Title: ENZYMES
Description: These notes give detail explanations about Enzymes The notes are very enriching and are very good for sciences students at the undergraduate and graduate levels and also good for medical students
Description: These notes give detail explanations about Enzymes The notes are very enriching and are very good for sciences students at the undergraduate and graduate levels and also good for medical students