Notesale: Turn your study into money

Document Preview

Extracts from the notes are below, to see the PDF you'll receive please use the links above

---

1001NSC Human Biology Semester Summary
Griffith University, Nathan Campus
Semester 1, 2014

Topics included:
- Blood
- The Cardiovascular System
- The Lymphatic System
- The Inflammatory Response
- The Immune System
- The Respiratory System
- The Digestive System
- Accessory Structures of the Digestive System
- The Renal System
- Sexual Reproduction
- The Male Reproductive System
- The Female Reproductive System
- Embryonic Development

Blood




Interstitial fluid (inside tissues)
o Bathes the cells of the body
 Nutrients and oxygen diffuse from the blood into interstitial fluid and then into the cells
 Wastes move in reverse direction
Blood
o Functions
 Transports nutrients/wastes/hormones
 Regulates of body temperature/pH
 Prevents of blood loss/infection
o Physical characteristics
 Thicker (more viscous) than water
 Temp of 38oC
 pH 7
...
45 (alkaline)
 8% total body weight
 5-6L males, 4-5L females
o Composition- 55% plasma, 45% cells
 Cellular- all originate form pluripotent stem cell
 Plasma- no cellular components
1
...
<1% White blood cells (leukocytes)
Properties:
o Amoeboid movement
 Crawling-like motility powered by actin cytoskeleton
 Allows cells to emigrate and seek-out bacteria
o Chemotaxis
 Directed migration of cells in response to chemical gradient
 Positive chemotaxis= chemoattractant
 Eg
...
Platelets (thrombocytes)
 Derived from giant bone marrow cell, megakaryocyte
 Fragments of cell membrane and cytoplasm (no nucleus)
 Production stimulated by thrombopoietin (TPO)
 Hormone produced in liver
 Contain assortment of proteins/other molecules
 Enable them to stick together in clot formation and tissue repair

o

Plasma (non-cellular components)
 90% Water
 7% Plasma proteins
 60% Albumin (major plasma protein)
 Produced in liver
 Transports molecules around circulatory system
 Buffers blood pH
 Aids in body heat distribution
 Maintains osmotic pressure of blood
 Decreased albumin leads to fluid leakage causing oedema
 The blood clotting system
 Hemostasis -stopping of bleeding
 Vascular spasm
 Platelet plug formation
 Coagulation (blood clotting)
 Serum= plasma without clotting system proteins
 Globulins
 Alpha, beta and gamma
 Other solutes
 Electrolytes, nutrients, hormones, gases, waste etc
...
Contraction of skeletal muscles in nearby tissues
2
...
Presence of valves in lymph ducts
4
...
Vasodilation
 Increase in diameter/permeability of blood vessels
2
...
Inflammatory mediator production/release (elicit vasodilation/diapedesis)
 Chemotactic factors released from sites of inflammation stimulate diapedesis of WBC's
(neutrophils)
 Neutrophils phagocytose inflammatory materials (bacteria, damaged tissue etc
...

 Chemical substances- toxins, venoms, proteases ect
...
Leucocytosis
 Bone marrow stimulated to release more WBC's into bloodstream to replace those lost



Fever
o

Systemic response to infection
 Caused by pyrogens (chemical substance released by WBC's/macrophages exposed to antigens)
 Alter thermostat regulation of hypothalamus
 Bacteria/viruses like to reproduce at body temp→body heats up as defence

The Immune System


Acquired- lymphocytes are taught what is self and non-self
o Naturally acquired
 Active- infection; contact with pathogen
 Passive- antibodies pass from mother to foetus
 Via placenta or breast milk
o Artificially acquired
 Active- vaccine; dead or attenuated pathogens
 Passive- injection of immune serum (antibodies)



Antigens
o Any chemical which provokes immune response (chemicals on surface of bacteria, virus etc
...
)
 Strongest antigens usually proteins
o Antigenic determinant- region of antigen which is immunogenic (recognised by antibody)
Antibodies (immunoglobulins Ig)
o Protective proteins secreted by activated B cells
o Bind to antigens
o 5 different types
 IgG- most abundant
 IgA- found in bodily secretions (saliva, mucus etc
...

o Alveolar pores
 Connect adjacent alveoli
 Allow air pressure to equalise, provides alternate route for air flow



The mechanics of breathing
o Breathing= movement of air into and out of lungs
o Under voluntary and involuntary control
o Occurs in response to pressure changes
 Controlled by volume changes in thoracic and pleural cavities
 Coordinated contractions of intercostal (between rib) and diaphragm muscles
 Inspiration- diaphragm contracts/chest outwards→volume increases→negative
pressure
 Expiration- diaphragm relaxes/chest inwards→volume decreases→positive pressure
 Intrapleural pressure stops lungs collapsing
 Intrapulmonary pressure= 760mmHg, Intrapleural pressure= 756mmHg
 Negative pressure of pleural cavity prevents lungs collapsing
Atelectasis (lung collapse)
 When air enters pleural cavity via chest wound/rupture of visceral pleura
Pneumothorax
 Presence of air within intrapleural space resulting in atelectasis
 Treated by closing the "hole" and removing air
 If one lung does collapse, it will not usually affect the other



Gas Exchange in Respiration
o Occurs by simple diffusion
 Dependent upon partial pressure (concentration) of each gas
 Partial pressures of O2 and CO2 at particular sites determine their uptake/unloading
 Respiratory membrane (PO2 high in alveoli)
 O2 taken up by haemoglobin
 CO2 released into lungs
 Body tissues and blood (PO2 low in tissue)
 O2 released to the tissues
 CO2 taken up by the plasma and RBCs

o

o

CO2 transport
 CO2 is much more soluble in water than O2
 Majority of CO2 is carried in plasma (~70%)
 Mainly transported as soluble bicarbonate (HCO3-) ions in plasma
 Carbonic acid-bicarbonate buffer system maintains blood pH
 The more CO2→ more acidic blood pH is
 Enhanced by carbonic anhydrase (enzyme in RBCs)
 Some (20-30%) bound to haemoglobin
 Binds to amino acids of globulin protein subunits (not heme)
 Forms carbamino-heamoglobin
O2 transport
 Relatively poor solubility in water, only small amount transported in plasma
 Majority bound to heme in haemoglobin of RBCs
 Allosteric binding- each O2 bound enhances the binding of the next O2
 Oxyhaemoglobin (HbO2)= fully/partially saturated with O2
 Deoxyhaemoglobin (HHb)= no O2 bound
 Rate of O2 binding is regulated by:
 PO2 (uptake increases with O2 partial pressure)
 PCO3 (uptake decreases with CO2 partial pressure)
 Temperature (increased temp
...
Duodenum (first 25cm)
 Contains bile duct from liver and pancreatic duct from pancreas
 Duodenal glands secrete alkaline, bicarbonate rich mucus→neutalise stomach acid
2
...
5m)
3
...
6m)
 Mesentery- serous membrane that binds intestines together/suspends them in abdominal wall
 Greater omentum- connective tissue and layer of fat for insulation, protection, support
 Main site for nutrient absorption
 Very efficient, >90% absorption of fluid due to large surface area
 Surface area increase by:
 Plicae circulares (circular folds of mucosa)
 Villi (finger-like projections of folded mucosa)
 Blood capillary system- absorbs amino acids/simple
sugars into blood
 Lymphatic vessel (lacteal)- absorbs lipids
 Microvilli (of individual cells)
 Brush-border cells
 Responsible for nutrient absorption
 Contain disaccharidases, lipases, proteinases
 Mucosa contains crypts (pits) which secrete intestinal fluid
 Bile secreted by liver enters via the gallbladder at the common bile duct in the duodenum
 Emulsifies fats aiding in lipid absorption into lacteals

o

o
o
o

o
o

Large intestine
 Four main sections:
1
...
Colon
 Ascending, transverse, descending, sigmoid
3
...
Anal canal
 Internal anal sphincter- involuntary smooth muscle
 External anal sphincter- external skeletal muscle
 Teniae coli- the longitudinal muscle is condensed into 3 ribbons
 Pulls large intestine into sacs called haustra
Main site of water absorption

 Large number of blood vessels
 No villi are present
 Large number of goblet cells (lots of mucus)
 Contains the bacteria flora
 Synthesise B complex vitamins and vitamin K
Haemorrhoids:
Enlarged, inflamed veins (usually varicose) within the anus
Due to increased pressure on the anal veins
Common in pregnancy, prolonged sitting, constipation, forms of obesity
...
5L per day of saliva per day
 Moistens food to aid in swallowing
 Cleanses the mouth/prevents overgrowth and infection of harmful bacteria
 IgA antibodies
 Lysozymes (bacteriostatic enzyme)
 Defensins (antibiotic proteins)
 Cyanide compound
 Dissolves food particles so they can be tasted
 Contains salivary amylase (commences starch breakdown)



Pancreas
o Exocrine: (Acini)
 Acinar cells- secrete pancreatic juice into GI tract via duct
 Alkaline (pH 8) bicarbonate-rich mixture
 Neutralises acidic chyme from stomach
 Contains enzyme precursors for protein digestion
 Duct joins the common bile duct to enter the small intestine
o Endocrine: (Islets of Langerhans)
 Alpha cells- secrete glucagon→ increase blood glucose levels
 Stimulates glucose release from liver where it is stored as glycogen
 Beta cells- secrete insulin→ decrease blood glucose levels
 Enhances membrane transport of glucose into tissue cells
 After glucose enters the cell, insulin triggers enzymatic activities:
 Catalyse oxidation of glucose for ATP production
 Joins glucose together to form glycogen
 Converts glucose to fat
 Delta cells- secrete somatostatin→ inhibits release of glucagon and insulin
 Gamma cells- secrete pancreatic polypeptide→ reduces appetite



Liver
o

Three main functions in digestive system:
1
...
5 to 1L per day)
 Produced/secreted by hepatocytes
 Bile then drains into ducts →eventually into gallbladder
 Derived from cholesterol and cholic salts
 High cholesterol levels lead to gallstones (crystals of pure cholesterol)
 pH 7
...
6 (alkaline)
 Emulsifies fats→aids in fat digestion/absorbtion into lacteals
 Deodorises faeces
 Bilirubin- main bile pigment (greenish/brown colour)
 Waste product of heme from worn out RBC's
 Metabolised by bacteria in small intestine→urobilinogen (brown colour of faeces)
2
...
Primary site of glucose storage for the body
 In the form of glycogen (a complex polysaccharide)

o

o

o
o

o
o
o


Composed of hexagonal liver lobules
 Contain a central vein with sheets of hepatocytes radiation outwards
 Portal triad at each point of the hexagon
 Consists of an arteriole, a venule and a bile duct
 Blood from arteriole/venule pass down sinusoids (leaky capillaries)
 Removes debris and worn-out blood cells
 Surrounded by sheets of hepatocytes
 Process blood-borne nutrients
 Store fat-soluble vitamins
 Detoxify the blood of toxins/metabolic wastes
 Produce bile→secreted into bile canaliculi that rins into bile duct of portal triad

Hepatitis:
Inflammation of the liver caused by dug toxicity, poisoning, viral infection
 Common hepatitis viruses A,B,B,D,E,F
 HVA, HVE- transmitted by contaminated food/water (vaccines available)
 HVB, HVC- carried in infected blood products/body fluids
 Vaccine for HVB, no vaccine or cure for HVC
 HVD- mutated virus that needs HVB to be infectious
 HVF- little in known
Heptomegaly- enlargement of the liver
Jaundice- bilirubin build-up in blood→yellow discolouration in skin
Cirrhosis:
Progressive, chronic liver inflammation typically a result of alcoholism
 Alcohol poisons/wears out hepatocytes
Fat accumulates in hepatocytes→fibrous scar tissue forms→liver becomes filled with fat/scar tissue
Scar tissue starts to tighten→blocks blood supply→liver dies

Gallbladder
o Small green sac lined with smooth muscle
o Right, lower surface of liver
o Stores and concentrates bile before release into small intestine
o Contraction stimulated by intestinal hormone cholecystokinin
 Intestinal hormone released when acidic, fatty chyme enters small intestine

The Renal System


Functions:
o Maintains water, salt and pH balance of blood (filters ~200L of blood per day)
o Removes toxic metabolic waste products (urea, creatinine, uric acid etc
...
5L/day)
o Recycles water/salts
 eliminates the need for constant drinking
o Hormone production
 Erythropoietin to stimulate erythropoiesis (production of RBCs)
o Enzyme production
 Renin for blood pressure regulation
o Activate Vitamin D to its active D3 form (calcitriol) to assist in bone formation
o Supplies glucose during prolonged fasting (via gluconeogenesis)



Kidneys
o Filtration of wastes from blood stream (highly vascularised organ)
o Both are in the upper abdominal cavity, protected by the 12th rib
 Right kidney is usually lower than the left
o Protected and insulated by:
 Renal fascia- outer, dense, fibrous tissue
 Adipose layer- middle layer of fat
 The renal capsule- inner, thin, shiny membrane on kidney surface
o Three regions:
 Outer cortex
 Site of filtration
 Light-coloured, granular appearance
 Inner medulla
 Site of reabsorption/excretion
 Dark, reddish-brown colour
 Arranged into series of pyramids
 Papilla- point of each pyramid (points inwards towards calyces)
 Renal pelvis
 Central junction that papilla points to
 Close by, a renal artery enters and a renal vein leaves
 Large, funnel-shaped collecting tube
 Calyces- branching extensions of renal pelvis
 Collect urine draining from the pyramids
 Walls of calyces, renal pelvis and ureter contain smooth muscle
 Propel urine along by peristalsis



Nephron- filtration unit
o Consists of:
 Glomerulus
 Pinhead sized tuft or arterioles with fenestrations (tiny holes)
 Allows fluids, solutes, wastes to leak out of bloodstream
 Basement membrane does not allow blood cells/large solutes to leak out
 Podocytes further filter fluid which has passed though basement membrane
 Pedicles- numerous foot-like projections restrict surface area for filtration
 Regulate amount of fluid being filtered
 Glomerular (Bowman's) capsule
 Cup-like structure holding the glomerulus
 Allows fluid to pass from blood to collecting tubules
 Renal capsule= glomerulus + Bowman's capsule
Renal tubule- collecting tube divided into 3 regions:

 Proximal convoluted tubule
 Loop of Henle
 Distal convoluted tubule
 Collecting duct

o

Urine formation involves 3 major processes
1
...
Tubular reabsorption
 Within the proximal convoluted tubule the following are reabsorbed back into the blood:
 Glucose, lactate, amino acids, 65% sodium ions, 65% of water
 Within the loop of Henle:
 Descending limb
 Freely permeable to water, impermeable to solutes/salts
 Extracellular space becomes hypertonic due to active pumping in ascending
limb
 Water moves by osmosis out of the descending limb and into the
extracellular space
 Ascending limb
 Impermeable to water
 Actively reabsorbs salt (sodium/chloride ions) back into blood from the urine
 Within the distal convoluted tubule/collecting duct:
 Hormone-dependent permeability to water





Antidiuretic hormone (ADH)
 Released by posterior pituitary gland
 Regulates water permeability of the collecting ducts
 Under ADH water is reabsorbed into blood→urine becomes more concentrated
 Alcohol inhibits ADH release
 Decreased water reabsorption, increased urine output, dehydration
Aldosterone
 A mineralocorticoid secreted by adrenal glands
 Enhances sodium reabsorption
 Water follows sodium back into blood (increases blood pressure)
 Urine becomes more concentrated
 Sodium reabsorption coupled with potassium secretion into urine

3
...
)
 Elimination of undesirable/toxic substances (urea, uric acid etc
...
Primary spermatocyte stage- daughter cell (from spermatogonia mitosis) separates and enters
meiosis
2
...
Spermatids are produced from second meiotic division
 Round, haploid cells without characteristic sperm shape
4
...
Growth
 Change in size due to mitosis
2
...
Morphogenesis
 Change in overall shape/organisation of embryo



Fertilisation
o Combining of gametes to form zygote usually occurs in fallopian tubes
 Ovum must be fertilized within 12-24 hours after ovulation
 Takes 72 hours for ovum to reach uterus
o Why so many sperm?
 Ejaculation contains 300 million
 Only 2000 reach ovum
 Loss by leakage
 Killed by acidic vaginal environment/destroyed by WBC's in uterus
 Failure to penetrate mucus of cervical canal
 Half will enter wrong fallopian tube
o Sperm can reach ovum in 10 minutes but cannot fertilize until capacitation (`10 hours)
 Removal of adherent seminal plasma proteins
 Reorganisation of cell membrane lipids and proteins
 Prior to ejaculation sperm head contained much cholesterol
 Toughens membrane preventing pre-mature release of acrosomal digestive
enzymes
 Acidic vaginal fluid washes away cholesterol/inhibitory factors
 Influx of extracellular calcium (due to increased sperm head permeability)
 Increase in cyclic AMP
 Decrease in sperm intracellular pH
 Sperm motility increases
o After capacitation sperm makes contact with zona pellucida of ovum
 Carbohydrate groups on zona pellucida glycoproteins function as sperm receptors
 Receptor-ligand interact (allows species specificity)
 Sperm surface proteins bind to receptors triggering acrosomal reaction
 Release of digestive enzymes from acrosome of sperm
 Cellular extension (actin filaments) from head guides sperm nucleus into cytoplasm of ovum
Monozygotic twins: (identical)
o Single ovum fertilised by one sperm
o Inner cell mass separates into two identical cell masses
o Single, shared placenta (one twin may receive more placental blood flow)
Dizygotic twins:
o Two separate ova fertilized by two different sperm
o Fused placenta



Blocks to polyspermy
o Humans only allow entry of one sperm into ovum (monospermy)
o Fast block
 Sperm enters ovum membrane
 Sodium ions rush into ovum
 Ovum membrane depolarises→no other sperm can penetrate
o Slow block (cortical reaction)
 Sperm enters ovum
 Calcium ions released from ovum's ER
 Cortical granules release enzymes (zonal inhibitory proteins) between ovum membrane and
zona pellucida
 Enzymes attract water filling the space→washes away/detaches other sperm



Cleavage
o First four cell divisions after fertilisation
o No increase in overall size of embryo
Morula (3 days)
o 16-cell structure
o Undergoes surface smoothing (compaction)
 Expression of first cell adhesion molecules
 Boundaries between adjacent cells become less obvious as cells become more adhesive
Bastula (4-6days)
o 100 embryonic cells organised into blastula (blastocyst)
 Trophoectoderm- outer, single layer of trophoblast cells
 Forms placenta
 Inner cell mass
 Forms embryonic disk→embryo
 Blastocyst cavity







Implantation (6 days)
o Syncytiotrophoblast cells release digestive enzymes onto endometrium
o Blastocyst attaches to uterine wall 6 days after ovulation
o Syncytiotrophoblast grows roots and digests way into endometrium
 Secretes HCG→stimulates corpus leteum hormone secretion to maintain endometrium and
prevent menstruation
 Becomes the chorion (blood supply) of the placenta
o Endometrium completely encloses implanting embryo
Ectopic Pregnancy
o Blastocyst implants somewhere other than uterus
 Mostly in uterine tube (tubal pregnancy)
 Tube unable to expand enough and ruptures by Week 12
 Embryo may re-implant in abdominopelvic cavity (adequate blood supply)



Gastrulation (2 weeks)
o Inner cell mass becomes three distinct tissue layers- primary germ layers
1
...
Mesoderm
 Musculo-skeletal system
 Circulatory system
 Dermis of skin
 Sub-epithelial layers of digestive tract/respiratory system
 Urinary system
3
...
Amniotic membrane (amnion)
 From ectoderm which completely surrounds embryo
 Fills with amniotic fluid
 Protects and supports embryo
2
...
Chorionic membrane (chorion)
 From mesoderm
 Outer layer- combines with the cytotrophoblast cells to form chorionic villi (blood
capillaries) within placenta
 Inner layer- protective layer around amniotic membrane
 Extra-embryonic coelom- space between inner/outer layers
Placenta
o Organ connecting foetus to uterine wall
o Allows nutrient uptake, waste elimination, gas exchange via mother's blood supply
 Foetal and maternal blood do NOT mix
o Placental conductivity increase as chorionic villi grow since membranes become thinner
Foetal circulation
o Umbilical-placental circuit via umbilical cord
o Spaces in mesoderm become lined with endothelium→merge into blood and lymph vessels
o Two side-by-side tubes fuse to form heart
Prenatal Nutrition
o Trophoblastic nutrition
 Embryo is nourished by digestion of endometrial cells and yolk sac
o Placental
 Foetus is nourished from mother's bloodstream through placenta








Parturition (40 weeks)
o During last two weeks of pregnancy, oestrogen reaches highest level
 Stimulates myometrium to form abundance of oxytocin receptors
o Cells within foetus begin to produce oxytocin
 Acts on placenta causing release of prostaglandins
o Oxytocin/prostaglandins are powerful uterine muscle stimulants
 Oxytocin also hormonal trigger for milk ejection from female mammary glands
o Increasing physical/emotional stress activates hypothalamus
 Triggers posterior pituitary gland to secrete oxytocin
 Positive feedback mechanism commences
 Untimely spurts of oxytocin can provoke premature births
Events of labour
o Process by which foetal is expelled from the uterus via the vagina
o Onset decreases effects of progesterone and increases effects of placental hormones:
 Relaxin- causes pelvic ligaments and pubic symphysis to relax, widen and become more flexible
 Human placental lactogen (hPL)- stimulates maturation of breasts for lactation
 Human chorionic thyrotropin- ensures foetus has adequate calcium
False labour- week, irregular contraction (Bracton Hicks contractions)
True labour- uterine contractions occur at regular intervals
o Contractions produce strong pain
o As interval between contractions shortens, contractions intensify (positive feedback)
o Discharge of blood containing mucus
o Three stages of true labour
 Dilation
 Dilation of cervix
 Rupture of amniotic membrane (water break)
 Expulsion
 From complete cervical dilation to delivery of baby
 The placental stage
 Placenta and foetal membranes are expelled
 Powerful uterine contractions constrict blood vessels torn during delivery
o During labour adrenal glands of foetus secrete epinephrine and norepinephrine
 Protect newborn against stress



Puerperium (until 6 weeks after pregnancy)
o Maternal reproductive organs return to pre-pregnancy state
 Uterus undergoes involution- reduction in size due to tissue catabolism
 Cervix loses elasticity and regains pre-pregnancy firmness
 Lochia- uterine discharge 2-4 weeks after deliver
 Initially containing blood and then serous fluid derived from former placental site



Post-natal development
o Respiratory adaption
 Baby's oxygen supply from mother ceases
 Blood carbon dioxide level increases stimulating respiratory centre in brain stem
 Inspiratory muscles stimulated to contract→vigorous exhalation and baby naturally begins to
cry
o Cardiovascular adaption
 Foramen ovale between atria closes at moment of birth to divert deoxygenated blood to lungs
 After umbilical cord is severed, distal portions of umbilical arteries become medial umbilical
ligaments and the umbilical vein becomes the round ligament of the liver
o Immunological adaption
 Maternal antibody (IgG) diffuses across placenta/IgA in breast milk



---