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

---

Circulatory system in mammals
Double circulatory system – blood travels through the heart twice for each complete circuit of the
body/ blood is pumped twice by the heart, from the right ventricle to the lungs and from the left
ventricle to the body
...
The other circuit from the heart to the rest of the body is the systemic circulation
...
Higher pressure in systemic circuit ensures oxygenated blood is pumped to all organs at
a pressure sufficient to deliver metabolites and remove waste at the rate required and also allows
tissue fluid to form
...
Fish has single
circulatory system, the blood is pumped through the gas exchange surfaces (gills) and the rest of
the body in the same circuit
...
Advantage of double
circulatory system over single circulatory system: it allows a two-pressure system with higher
pressure to the body cells and lower to the lungs
...

Arteries carry oxygenated blood away from
the heart while veins carry deoxygenated
blood into the heart
...
Capillaries then combine to form
venules which combine to form veins
...

Coronary arteries arise from the base of the
aorta
...
Squamous
endothelium wall provides a smooth inner surface which reduces the friction
caused by blood flow through lumen
...


fibres) since blood is
under low pressure
Large lumen provides
large space making it
easier for blood to
enter from capillaries
while friction is
reduced as blood
flows back to the heart
– little resistance to
blood
Semilunar valves
prevent backflow of
blood caused by low
pressure
As the pressure is low,
gravity and force
created by the
contraction of muscles
helps transport blood

to water and solutes allow
gases or substance to dissolve
and diffuse – facilitate
exchange of substance
between the blood and tissue
cells
Small size allow extensive
network of capillaries
providing large SA for max
diffusion
RBC squeeze their way
through capillaries, further
reducing diffusion distance
between RBC and lungs or
tissues
Close to body cells
Blood flows slowly giving time
for diffusion
More extensive in organs
where the metabolic rate is
high

Blood is squeezed along when skeletal muscles contract

Tissue fluid is formed at the arterial end of capillaries because the blood has a high hydrostatic pressure
(due to pumping of the heart)
...
Polymorphs and monocytes (white blood cells) can also leave capillaries,
squeezing between adjacent endothelial cells at sites of infection
...
Tissue fluid carries glucose, ions and oxygen to
the cells
...
Thus at the venous
end, due to the low solute potential of the blood, fluid (ie
...


Hydrostatic pressure – pressure created from heart contraction when fluid is forced out of capillaries and
into space around the cells
Tissue fluid – fluid that leaks out of capillaries (through tiny gaps) dissolved gases and nutrients move with it
Ultrafiltration - A high pressure filtration through a semipermeable membrane in which colloidal particles are
retained while the small sized solutes and the solvent are forced to move across the membrane by
hydrostatic pressure forces
...

O2, glucose and
other materials
enter cell by
diffusion

After
supplying
metabolite,
the returning
fluid
transports
CO2 and
other waste
products

Loss of fluid
/ solutes
from
capillary
causes a
reduction
in
hydrostatic
pressure

By the time
the blood
reaches the
venule end,
hydrostatic
pressure of
tissue fluid
exceeds the
hydrostatic
pressure of
the blood

1
...

Functions: osmoregulation
(the maintenance of constant
osmotic pressure in the fluids
of an organism by the control
of water and salt
concentrations) of the cells
and facilitate the transport of
substances between the
blood and the body cells
...

The return of tissue fluid to
capillaries is aided by the
difference in Ѱ between
blood and tissue fluid
...
Lower Ѱ of blood, due to the presence of plasma proteins, that tends to pull the tissue fluid back by
osmosis
2
...
Adaptation: large
number – more oxygen can be carried;

small size – haemoglobin molecules must
be close to the cell surface to aid diffusion
and easier to flow through narrow
capillaries; shape – high SA:V ratio due to
biconcave shape; no nucleus or organelles
– more room for haemoglobin and O2;
haemoglobin – carry O2, being in RBC
decreases the Ѱ of blood and viscous
...
Each RBC has large number of
haemoglobin molecules
Polymorphs

Monocytes

Microphages; most common (70%)
(numerous) white blood cells; multi-lobed
nucleus and granular cytoplasm; shortlived
Largest; least common; bean-shaped
nucleus; long lived

Lymphocytes

Very large nucleus leaving only a small
amount of cytoplasm; quite a large
number

Platelets

Cell fragments which are very small to be
visible using a light microscope
Consists of 90% of water and variety of
substances in solution and suspension:
plasma proteins including prothrombin and
fibrinogen, albumin and enzymes,
hormones, glucose, amino acids, fats and
fatty acids, urea, vitamins and ions eg
...
They release clotting factors like thromboplastin (enzyme) and form a plug to
seal minor damage to reduce rate of blood loss if damage is great
...
Calcium ions, Vitamin K,
clotting factors VIIIa and Xa is required
...
As it dries, the clot forms a scab,
both preventing blood loss and entry of microbes
...
___ = function
Removal of calcium ions is used to prevent blood donated
by another individual from clotting
...
Certain
types of medical treatment can increase risk of a clot
forming within the blood vessel even if vessel is not
damaged
...
In addition, low pressure, slower rate of blood flow
through lung capillaries, more time for diffusion/exchange of gases
Thick muscular wall that runs through the centre of the heart
...
pulmonary artery carries blood away from the heart, it’s structurally similar to other arteries
...
2s and E is caused by the
atria filling with blood
P - wave represents the wave of electrical stimulation that triggers the contraction of the atria
Short and straight line between P and Q – represents the wave of excitation passing through the AV node
QRS - complex represents the electrical activity that stimulates contraction of ventricles
R – peak has a greater amplitude than P as there is much greater electrical activity in the ventricles since it’s
larger and has thicker muscle
T – wave represents the relaxation of the ventricles (the ventricles are repolarised)

Cardiac muscle is myogenic meaning contraction originates in the heart itself and does not depend on
nervous stimulation/ doesn’t require external stimulation

SAN generate its own nerve impulse
Pacemaker – where nerve impulse starts
SAN is under nervous system control thus
rate of heartbeat can be increased or
decreased in time of need through
external nervous control eg
...
The only way electrical activity can
pass is through to ventricles is via AV nodes; conduct slowly – contraction in ventricles is
delayed relative to atria – ensuring when ventricular systole begins, atrial systole is complete
(atria to empty) and ventricles is completely filled with blood
Bundle of His
Special tissue which electrical activity can pass down the septum of ventricles to the
bottom of the ventricles
Purkinje fibres Special tissue which stimulation spreads up through the walls of ventricles causing
contraction of ventricle walls and forcing blood up through the arteries (ventricle systole);
branch upwards (wave travels upwards) causing them to contract from the bottom up to
ensure blood is pushed up from the ventricles into the arteries
Blood is pushed by contraction of muscles which constricts (narrows) the arteries

Coronary heart disease (CHD) – heart attack caused by damage to coronary arteries that supply the heart
with blood, carrying glucose and O2 for respiration
ATHEROMA:
It’s build-up of fatty deposits that form within wall of an artery
Risk factors: smoking, lack of exercise, too much salt in diet, stress, high blood
cholesterol levels
Risk factors that can’t be controlled: age and genetic predisposition –
possessing genes that increase an individual’s susceptibility to a certain
disease
Squamous endothelium cells lining artery lumen is damaged
Due to toxins in blood from tobacco smoke in cigarette or high blood pressure
applying greater force on the artery walls
Macrophages from monocytes migrate from blood into
damaged wall
They accumulate cholesterol, dead muscle cells, fibrous
tissue within the wall
Atheroma builds up into hardened plaques
As size and toughness increase, plaques bulge into the
lumen narrowing and restricting blood flow
Build-up of fibrous tissue cause artery to become less elastic
(and harden) and less able to regulate blood flow through
vasodilation or vasoconstriction
Narrowing of arteries makes more difficult for blood to flow through it
...
statins) to lower cholesterol/sugar level in blood or pressure or
prevent inflammation; coronary bypass – (leg)arteries or veins from other areas in your body are
used to bypass or go around your narrowed coronary arteries; surgery to widen the arteries;
angioplasty - used to open blocked or narrowed coronary (heart) arteries
...
Sometimes a small mesh tube called a stent is
placed in the artery to keep it open after the procedure
Could lead to stroke
(CORONARY) THROMBOSIS:











Blood platelets tend to collect at the damaged surface of artery and release
factors that trigger blood clotting
formation of blood clots within blood vessels is called thrombus, narrowing
the arteries
condition is called thrombosis
More likely to happen if the artery wall becomes damaged
Heart muscle fails to receive blood and thus O2 and glucose for respiration –
they will be permanently damaged
Cells die leading to myocardial infarction (heart attack)
Myocardial – occurring in heart muscle / infarction – death of tissue resulting
from oxygen deprivation
If large artery is blocked the whole heart may stop beating – cardiac arrest
Occurs near the origin of coronary artery than near the tip

ANEURYSM:
Atherosclerosis can lead to weakening of a section of artery wall
which due to pressure of blood
Artery will bulge outwards forming a balloon-like sac in the artery
called aneurysm

It may burst causing massive bleeding which is fatal
Blood loss from brain can put pressure on the brain causing stroke
DIAGNOSIS OF CARDIOVASCULAR DISEASE:
 Angiography is a medical imaging technique that allows doctors to see inside blood vessels
 Contrast agent is released into artery via catheter, making blood vessels visible when an X-ray is taken
 Tube is pushed through the blood vessels until it reaches the part of body under investigation to place
the contrast agent on only where needed
 Angiogram shows the blood flow through the blood vessels and allows various blood flow abnormalities
to be detected eg
...
When the
first O2 molecule combines with the first haem group, the shape of the Hb molecule
becomes distorted
...
Both a decrease in pO2 and an
increase in pCO2 causes more O2 to be released from Hb
High ppCO2 occurs when respiration rate is high eg
...
This involves: increase in number of RBC (production); increased
ventilation



therefore increased levels of haemoglobin in the body and more O2 can be transported to
muscles



Utilised by athletes in high altitude training to increases RBC
production
Populations that have lived in high altitudes for many
generations have evolved a type of Hb that saturates at lower
ppO2 (has a higher affinity for oxygen) than the typical
lower altitude populations
Eg
...
underground,
during migration, fish living in less oxygenated water
Sign of lack of O2: breathlessness, nausea and fatigue due to
lack of O2 in brain







DNA analysis allow to see if you have genes that increase the risk of cardiovascular disease
Benefit – if you are at high risk of cardiovascular disease, you can take action to reduce other risk factors
Problem – insurance companies might want to know if you are at high or low risk, which would affect the
premiums that you pay

Polymorphs



---