mass transport in animals Flashcards
Describe the role of red blood cells and haemoglobin in oxygen transport
Red blood cells contain lots of haemoglobin (Hb) - no nucleus, biconcave, high SA:V, short diffusion path
● Hb binds with O2 gas exchange surfaces where partial pressure of O2 (pO2) is high
● This forms oxyhaemoglobin which transports O2 (each can carry 4O2 - one at each Haem group)
● Hb unloads O2 near cells / tissues where pO2
is low
Describe the structure of haemoglobin
●Globular protein with a quaternary structure
● Made of 4 polypeptide chains
● Each chain contains a Haem group containing an iron ion (Fe
2+
Describe the structure of haemoglobin
●Globular protein with a quaternary structure
● Made of 4 polypeptide chains
● Each chain contains a Haem group containing an iron ion (Fe
2+
Describe the loading, transport and unloading of oxygen in relation to the oxyhaemoglobin dissociation curve in areas with low ppO2 (respiring tissues)
Hb has a low affinity for O2
● So O2 readily unloads dissociates with Hb
● So % saturation is low
Describe the loading, transport and unloading of oxygen in relation to the oxyhaemoglobin dissociation curve in areas of high ppO2 (gas exchange surfaces)
● Hb has a high affinity for O2
● So O2 readily loads with Hb
● So % saturation is high
Describe evidence for the cooperative nature of oxygen binding
A low pO2 as oxygen increases there is little / slow increase in % saturation of Hb with oxygen
○ When first oxygen is binding
● At higher pO2
* as oxygen increases there is a big / rapid increase in % saturation of Hb with oxygen
○ Showing it has got easier for oxygens to bind to
Explain why different types of haemoglobin can have different oxygen transport properties
Diff types of Hb made of polypeptide chains with slightly different amino acid sequences.
● meaning different tertiary / structures and shape→ different affinities for oxygen
What is the Bohr effect?
Effect of CO2 concentration on dissociation of oxyhaemoglobin → curve shifts to right
Suggest the importance of a double circulatory system
● Prevents mixing of oxygenated / deoxygenated blood
*So blood pumped to body is fully saturated for aerobic respiration
● Blood pumped to body at a higher pressure ( heart re-pumps blood after it returns from the lungs, so it doesn’t lose pressure like in a single circulatory system.)
○ Substances taken to and removed from body cells quicker
How does the double circulatory system help allow blood to be pumped at higher pressures
Double circulatory system consists of:
pulmonary circulatory- blood to lungs
systematic circulatory- blood from lungs to around body
They operate at different pressures (systematic higher) as it has to pump blood around the body
Role of Vena Cava
Transports deoxygenated blood from respiring tissues to heart
Pulmonary Artery Role
Transports deoxygenated blood from heart to lungs
Pulmonary Vein Role
Transports oxygenated blood from lungs to heart
Aorta Role
Transports oxygenated blood from heart to respiring tissues
In what order is blood transpoted in the heart?
Deoxygenated:
*deoxy blood enters the right atrium via the vena cava from respiring tissues.
* right atrium contracts, and blood passes through right atrioventricular valve into the right ventricle.
*right ventricle contracts, pushing blood through the semi-lunar valve into the pulmonary arteries, which transport blood to the lungs for oxygenation.
Oxygenated Blood Pathway
*Oxygenated blood returns to the left atrium via the pulmonary veins from the lungs.
*left atrium contracts, and blood passes left atrioventricular valve into the left ventricle.
*left ventricle contracts, forcing blood through the semi-lunar valve into the aorta, which distributes oxygenated blood to the body’s respiring cells.
What’s the general pattern of blood circulation in a mammal
Deoxy:
Renal veins – deoxygenated blood to vena cava from kidneys
and process continues…
Oxygenated:
Renal arteries – oxygenated blood from aorta → kidneys
Suggest why the wall of the left ventricle is thicker than that of the right
● Thicker muscle to contract with greater force
generate higher pressure to pump blood around entire body
Suggest why the wall of the left ventricle is thicker than that of the right
● Thicker muscle to contract with greater force
generate higher pressure to pump blood around entire body
Whats tissue fluid
*plasma tht has been transported out of pores of capillaries
Whats the difference between tissue fluid and plasma
Tissue fluid contains fewer proteins because proteins are large and arent able to go thru capillary pores
Whats the role of veins
Veins carry blood to the heart at low pressure
*receive blood that has passed thru capillary networks
Structure of veins and explain why
Veins have
*wide lumen- less resistance to blood flow
*thin layer of muscle and elastic fibers- lower blood pressure
*thinner wall compared to arteries
*contains valves
Structure of arteries and explain why
*narrow lumen- miantain high pressure
*thick layer of muscle, elastic fibers- allows wall to contract and recoil when heart relaxes.
*thick arterial walls- wiyhstand high pressure
Function of arteries
carry blood AWAY from the heart
Function of capillaries
allow efficient exchange of substances between blood and tissue fluid (exchange surface)
Structure of capillaries and why
*one cell thick- short diffusion distance from 02 and C02 in blood
*small diameter/lumen- reduces blood flow rate so more time for diffusion
*pores in wall- allow plasma to leak out and form tissue fluid.
*Capillary bed is a large network of branched capillaries → increases surface area for diffusion
Explain the return of tissue fluid to the circulatory system
At the venule end of capillaries:
*Hydrostatic pressure reduces as fluid leaves capillary
* cause of water loss increasing conc of plasma proteins lowers water potential in tissue fluid
*Water enters capillaries from tissue fluid by osmosis down a water potential gradient
*Excess water taken up by lymph capillaries ,returned to circulatory system through veins
Give pathway blood takes when travelling the human circulatory system from the kidneys to the lungs.
Renal vein
Vena cava to right atrium
Right ventricle to pulmonary artery
Give pathway blood takes when travelling the human circulatory system from the kidneys to the lungs.
Renal vein
Vena cava to right atrium
Right ventricle to pulmonary artery
explain how an arteriole can reduce the blood flow into capillaries
muscle contracts and constricts lumen
explain how an arteriole can reduce the blood flow into capillaries
Muscle contracts and constricts lumen
Explain the role of the heart in the formation of tissue fluid
*contraction of ventricle produces high hydrostatic pressure which forces the water out
Lymphoedema is a swelling in the legs which may be caused by a blockage in the lymphatic system. Suggest how a blockage in the lymphatic system could cause lymphoedema
Excess tissue fluid can’t be reabsorrbed
Give 2 structural features of an aorta wall and explain how they are related to the function of an aorta
(Smooth) muscle resists/withstands high blood pressure;
2. Elastic (tissue/layer) stretches and recoils maintains/smooths blood pressure;
3. (Smooth) endothelium reduces friction;
4. Protein (coat) prevents (artery) wall splitting
The hydrostatic pressure falls from the arteriole end of the capillary to the venule end. Explain why
Loss of water / loss of fluid / friction (against capillary lining).
High blood pressure leads to accumulation of tissue fluid. Explain how
High blood pressure = high hydrostatic pressure;
2. Increases outward pressure from (arterial) end of capillary
3. (So) more tissue fluid formed / less tissue fluid is reabsorbed.
Allow lymph system not able to drain tissues fast enough
Water potential of the blood plasma is more negative at the venule end of the capillary than the arteriole end of the capillary. Explain why
Water has left the capillary;
2. Proteins (in blood) too large to leave capillary;
3. Increasing / giving higher concentration of blood proteins (and thus wp).
Explain how the structure of arteries relates to their function
*Thick smooth muscle tissue and walls can contract withstand blood flow / pressure
*Thick elastic tissue
-can stretch as ventricles contract recoil as ventricles relax, to maintain high pressure
*Smooth / folded endothelium -Reduces friction
*Narrow lumen maintains high pressure
Explain how the structure of arterioles relates to their function
Function –control blood flow from arteries to capillaries
● Thicker smooth muscle layer than arteries
○ Contracts → narrows lumen → reduces blood flow to capillaries
○ Relaxes → widens lumen → increases blood flow to capillaries
● Thinner elastic layer → pressure surges are lower (as further from heart / ventricles)
Function of coronary arteries
carry oxygen/glucose
to heart muscle/tissue
What does diastole mean
*relaxation of cardiac muscles
* allows the chambers to fill with blood.
What does systole mean
*heart muscle contracts and pumps blood from the chambers into the arteries.
Explain the pressure & volume changes and associated valve movements
during diastole
● Atria & ventricles relax
● So their volume increases,
pressure decreases
● Semilunar valves shut when
pressure in arteries exceeds
pressure in ventricles
● Atrioventricular valves open
when pressure in atria
exceeds pressure in ventricles
● So blood fills atria via veins &
flows passively to ventricles
Explain the pressure & volume changes and associated valve movements
during atrial systole
● Atria contract
● So their volume decreases,
pressure increases
● Atrioventricular valves open
when pressure in atria
exceeds pressure in ventricles
● Semilunar valves remain shut
as pressure in arteries
exceeds pressure in ventricles
● So blood pushed into
ventricle
Explain the pressure & volume changes and associated valve movements
during ventricular systole
● Ventricles contract
● So their volume decreases,
pressure increases
● Atrioventricular valves shut
when pressure in ventricles
exceeds pressure in atria
● Semilunar valves open when
pressure in ventricles exceeds
pressure in arteries
● So blood pushed out of heart
through arteries
Describe the equation for cardiac output
Cardiac output= heart beats x stroke volume
Whats the purpose of tissue fluid?
*surrounds body cells
*provides cells with oxygen and nutrients
*gets rid of waste like co2
Explain four ways in which the structure of the aorta is related to its function.
*Elastic tissue to allow stretching / recoil / smoothes out flow of blood / maintains pressure.
*(Elastic tissue) stretches when ventricles contract
*Muscle for contraction / vasoconstriction;
*Thick wall withstands pressure
*Smooth endothelium reduces friction;
* Aortic valve / semi-lunar valve prevents backflow.
