Exchange- Mass transport in Animals Flashcards
Why is the transport system in mammals called a double circulatory system?
the heart pumps twice, the blood goes through the heart twice – generates enough pressure
to supply all body cells
Why is the transport system in mammals called a closed circulatory system?
blood is transported in blood vessels – helps to maintain pressure and redirect blood flow
Layout of Circulatory System?
heart pumps blood which is carried in arteries which flow into arterioles which flow into capillaries which then are carried in venules then veins back to the heart
Artery to Arterioles to Capillaries to Venules to Veins
Artery/Arterioles carry blood away from the heart
(arterioles are small arteries)
Capillaries are the site of exchange (nutrients out, waste in)
Veins/Venules return blood back to the heart
(venules are small veins)
Heart?
job is to pump blood around the body (delivers nutrients to cells and remove waste)
made of 4 muscular chambers (2 atria, 2 ventricles)
atria pumps blood to ventricles, ventricles pump blood out of heart (R to lungs, L to body)
ventricles thicker then atria (has to pump blood further)
left ventricle has a thicker muscular wall then right ventricle, therefore has stronger contractions, so can
generate higher pressure and pump the blood further around the body
Blood vessels of the heart?
artery takes blood away from the heart, vein returns blood to the heart
Vena Cava supplies R atrium (with deoxygenated blood from body)
Pulmonary Vein supplies L atrium (with oxygenated blood from lungs)
R ventricle supplies Pulmonary Artery (deoxygenated blood to lungs)
L ventricle supplies Aorta (oxygenated blood to body)
Job of valves in heart?
Ensure one way flow of blood, no backflow
(blood flows from atria to ventricles to arteries)
2 sets of valves: Atrio-ventricular Valve & Semi-lunar Valve
AV valve = between atria and ventricles
SL valve = between ventricles and arteries
When are AV valves open or closed?
Open = pressure in atria greater then pressure in ventricles,
Closed = pressure in ventricles greater then pressure in atria
When are SL valves open or closed?
Open = pressure in ventricles greater then pressure in arteries, Closed = pressure
in arteries greater then pressure in ventricles
Cardiac cycle
Diastole
atria relaxed, ventricles relaxed, AV valve open, SL valve closed
Atrial Systole
atria contracts and pushes all the remaining blood into the ventricles so it becomes full
Ventricular Systole
the ventricles contract from the base upwards, pushing the blood up thru the arteries, when the ventricles start to contract the AV valve closes then the SL valve opens and blood leaves the heart
Formula for Cardiac Output?
CO = Stroke Volume x Heart Rate
stroke volume = volume of blood pumped out of the heart in one beat
heart rate = number of beats per minuted
Cardiac Output = volume of blood pumped out of the heart in one minute
Role of Arteries/Arterioles?
generally carry oxygenated blood away from the heart
Coronary Artery - heart muscle
Hepatic Artery to liver
Renal Artery to kidneys
exception = Pulmonary Artery carries deoxygenated blood to lung
Role of Veins/Venules?
generally carry deoxygenated blood back to the heart
Coronary Vein -heart muscle
Hepatic Vein from liver
Renal Vein from kidneys
exception 1 = Pulmonary Vein carries oxygenated blood back to the heart
Function of Arteries/Arterioles?
carry blood away from the heart so should be able to withstand high blood pressures & maintain high blood pressures
Structure of Arteries/Arterioles?
narrow lumen = maintains pressure
lining made of squamous epithelial cells = smooth lining to reduce friction
thick wall = withstand pressure
elastic tissue stretches and recoils to withstand pressure
Function of Veins/Venules?
return blood back to the heart, the blood is under low pressure
Structure of Veins/Venules?
wide lumen = ease of blood flow
lining made of squamous epithelial cells = smooth lining to reduce friction
thin wall = vein can be squashed by skeletal muscle pushing blood back to the heart
valves in lumen = prevents backflow of blood
Function of Capillaries?
site of exchange
3 locations,
takes in O2 and removes CO2
deliver nutrients and remove waste
Adaptation of Capillaries?
many small capillaries = large surface area
thin wall, one cell thick = short diffusion distance
pores between cells = allows fluid to move in and out
narrow lumen = increase diffusion time and decrease diffusion distance
How does exchange occur between Capillaries & All Cells?
by mass flow
fluid moves out of the blood in the capillaries carrying the nutrients
fluid moves back into blood in the capillaries carrying the waste
(fluid in the blood called plasma, fluid surrounding cells called tissue fluid, fluid in lymph system called
lymph)
How is tissue fluid formed and returned to circulatory system?
at the start of the capillary (arterial end) there is a build up hydrostatic pressure
this pushes fluid out of the capillary via the pores
the fluid carries the nutrients with it
the fluid surrounds the cells, this is called tissue fluid
at the finish of the capillary (venous end) the fluid moves back in by osmosis
the capillary has low water potential due to the presence of proteins (too large to move out of capillaries)
any excess tissue fluid is picked up by the lymph system and deposited in the vena cava
Why does high blood pressure cause accumulation of tissue fluid?
increases hydrostatic pressure, so more tissue fluid is formed – not as much can be returned to the
circulatory system
Why does diet low in protein cause accumulation of tissue fluid?
the water potential in the capillary is not as low as normal, so not as much fluid can move back into the
capillary by osmosis
Job of Red Blood Cells?
found in humans/mammals (animals)
carries haemoglobin
haemoglobin carries oxygen
Structure of Haemoglobin?
protein
quaternary structure made of 4 polypeptide chains
each chain carries a haem group
each haem group carries Fe2+
each Fe2+ carries an O2
therefore, each haemoglobin carries 4 lots of O2
Job of Haemoglobin?
load oxygen in the lungs and deliver it to the respiring tissues
What is Affinity?
the level of attraction haemoglobin has to oxygen
high affinity = strong attraction, low affinity = weak attraction
Role of haemoglobin in oxygen transport?
haemoglobin has High Affinity in the lungs – due to high partial pressure of oxygen and low partial
pressure of carbon dioxide, so haemoglobin loads/associates oxygen in the lungs and becomes saturated
the haemoglobin is transported in the blood in the red blood cell
at the respiring tissues, haemoglobin has Low Affinity – due to low partial pressure of oxygen and high
partial pressure of carbon dioxide, so oxygen is unloaded/dissociated/delivered and haemoglobin becomes
unsaturated
Relationship between O2 Partial Pressure & Affinity/Saturation of Haemoglobin?
positive correlation
as O2 partial pressure increases, affinity/saturation of haemoglobin increases
the correlation is not linear but is curved (produces a s-shaped curve called Oxygen Dissociation Curve)
middle portion of ODC has a steep gradient so when respiring tissues change from resting to active and
partial pressure of O2 falls, there is a large drop in affinity, so more O2 would be delivered to the respiring
tissues
Relationship between CO2 Partial Pressure & Affinity/Saturation of Haemoglobin?
negative correlation
as CO2 partial pressure increases, affinity/saturation of haemoglobin decreases
this occurs at the site of respiring tissues = the carbon dioxide lowers the pH of the blood, makes the
haemoglobin change shape, so oxygen is released, lowering affinity. this shifts the ODC to the right,
called the bohr effect. more oxygen delivered to respiring cells