Mass Transport In Animals Flashcards
Which 4 blood vessels do we need to be aware of?
Arteries
Arterioles
Vein
Capillary
What is the main purpose of arteries?
Carry blood away from the heart
What are the structural features if an artery?
Thick muscular walls
Elastic tissue fibres
Folded endothelium
No valves
How do the structural features if an artery relate to its function?
Thick muscular walls - maintain high pressure to supply cells with oxygenated blood for aerobic respiration
Elastic tissue fibres - stretch and recoil as the heart beats to maintain blood pressure
Folded endothelium - allows the artery to stretch to maintain high pressure
No valves due to small lumen and high pressure preventing back flow of blood
How do the thick muscular walls of an artery relate to their/its function?
Maintains high pressure to supply cells with oxygenated blood
How do elastic tissue fibres in arteries aids their function?
Allows the artery to stretch and recoil as the heart beats ( maintain high pressure)
How does the folded endothelium in arteries aids its function?
Allows the artery to stretch to maintain pressure
What are arterioles?
A narrower branch of artery (blood vessels) which transports blood into capillaries
Describe the structure of arterioles?
Form a network
Involuntary smooth muscle
How do arterioles structure relate to its function?
Form a network - allows blood to be directed to different areas of demand within the body
Involuntary smooth muscle - contracts to cause vasoconstriction and reducing if the lumen to minimise blood flow to a specific area ( regulate blood flow to capillaries)
Why do arterioles forming a network aid their function?
allows blood to be directed to different areas of demand within the body
How does involuntary smooth muscle in arterioles aids its function?
Involuntary smooth muscle - contracts to cause vasoconstriction and reducing if the lumen to minimise blood flow to a specific area ( regulate blood flow to capillaries)
What is the purpose of a vein?
Carries deoxygenated blood towards the heart
What are the structural features of a vein?
Wide lumen
Thin layer of muscle and elastic fibres
Contain valves
How do structural features of a vein impact its function
Wider lumen - low blood pressure so don’t need to withstand high pressure
Thin layer of elastic and muscle tissue - carry more blood back to the heart
Valves - prevent the back flow of blood due to low pressure.
How does a wide lumen and thin layer of muscle and elastic fibres aid veins function?
Wider lumen - low blood pressure so don’t need to withstand high pressure
Thin layer of elastic and muscle tissue - carry more blood back to the heart
How do valves aid the function of veins?
Prevent backflow of blood due to low pressure (and blood pooling)
What are capillary?
They are networks which link/connect veins and arteries
(Networks are known as capillary beds)
What are the structural features of a capillary?
Narrow lumen (7um - size of red blood cell)
Highly branched and numerous capillary beds
Single layer of endothelial cells
How do the structural features of a capillary aids its function?
Narrow lumen - short diffusion distance for gas exchange and force blood to travel more slowly
Highly branched and numerous - increases surface area for gas exchange to cells for aerobic respiration
Single layer of endothelial cells Reduces diffusion distance between blood and tissues
Why is the hydrostatic pressure in arteries high?
The pumping/contraction of the heart
What happens to hydrostatic pressure as you get further away from the heart?
It drops/reduces
Why does hydrostatic pressure in capillaries drop?
The pressure drops due to a leakage of water from plasma in capillaries to surrounding tissues to form tissue fluid
What is a closed system?
blood is pumped around the body and is always contained within a network of blood vessels
Why do mammals require a circulatory system?
We have a low surface area to volume ratio so requiem a mass transport system to carry raw materials from specialised exchange organs to their body cells
What is the cardiac cycle?
The process which occurs to make up one heart beat
What are the three stages of the cardiac cycle?
Atrial systole
Ventricular systole
Diastole
Describe the process which occurs during ATRIAL SYSTOLE?
Atria contract and ventricles relax
Blood moves from the right and left atrium into the ventricles
The atrioventricular valve (AV valve) opens and the semi-lunar valve is closed as the pressure in the atria is greater than the pressure in the ventricles
Describe the process which occurs during VENTRICULAR SYSTOLE?
Ventricles contract and the atria relax
Blood moves from ventricles into the aorta or pulmonary artery
The AV valve closes to prevent backflow of blood but the semi lunar valve opens because the pressure in the arteries is lower than that of the ventricles
Describe the process which occurs during DIASTOLE?
Both atria and ventricles relax
The higher pressure in the pulmonary artery and aorta cause the semi lunar valves to close
Blood enter the atria due to high pressure of vena cava and pulmonary vein
This increases pressure in the atria causing the AV valve to open - allows blood to passively flow into ventricles
Why do atria have thinner muscular walls than the ventricles?
Atria have thinner walls as it pumps blood a shorter distance
Ventricles require a stronger muscular contraction due to larger pumping distance
What is the equation for cardiac output?
Cardiac output = stroke volume x heart rate
What is cardiac output?
Volume of blood pumped by the heart per min (cm3min-1)
What is stroke volume?
Volume of blood pumped out of the heart during each beat (cm3)
What is a double circulatory system?
blood passes through the heart twice per circuit. The right pump sends deoxygenated blood to the lungs where it becomes oxygenated and returns back to the heart. The left pump sends the newly oxygenated blood around the body.
What is the importance of a double circulatory system?
Increases blood pressure and rate if blood flow to the tissues is greater
Important in mammals as they have a high metabolism
What is the purpose of the coronary artery?
Supply the cardiac muscle with oxygenated blood
Name both the atrioventricular (AV) valves?
Bicuspid valve (left)
Tricuspid valve (right)
What is the role of haemoglobin?
Transport oxygen to respiring cells
Describe haemoglobin s structure?
It is a globular protein with a quaternary structure (4 polypeptides) and each chain has a haem group that contains an iron ion
How many oxygen molecules does it take for haemoglobin to become fully saturated?
Hb + 402 —> HbO8
What is affinity?
The tendency of a substance to combine with another
What is partial pressure of oxygen?
It is a measurement of the concentration of dissolved oxygen
How does a high partial pressure of oxygen affect haemoglobins affinity?
High partial pressure of oxygen leads to a higher affinity for oxygen and association/loading with oxygen
How does a low partial pressure of oxygen affect haemoglobins affinity?
Low partial pressure of oxygen leads to a lower affinity for oxygen and disassociation/unloading with oxygen
Where in the body would you find a low partial pressure of oxygen?
Respiring tissues - causes Hb to have a low affinity for oxygen leading to dissociation
Where in the body would you find a high partial pressure of oxygen?
Alveoli - causes Hb to have a high affinity for oxygen leading to association
What is cooperative binding?
Binding of one molecule affects the binding affinity of subsequent molecules
What shape of graph is formed due to cooperative binding?
A sigmoidal shape
Explain why a sigmoidal shape is formed when comparing partial pressure of oxygen and haemoglobin saturation?
When the first oxygen molecule bind to the haemoglobin a conformational shape change ( altering in the tertiary structure) allows higher affinity by exposing other binding sites
As HB becomes more saturated it’s harder for O2 molecules to associate (plateau)
What is the Bohr effect?
An increase in partial pressure of carbon dioxide causes the oxyhemoglobin dissociation curve to shift to the right
What happens to the oxygen dissociation as partial pressure of carbon dioxide (ppCO2) increase?
At a higher ppCO2 (at the same ppO2) haemoglobin has a lower affinity for oxygen
This means oxygen dissociates from haemoglobin more quickly at cells (carrying out aerobic respiration)
What happens to the oxygen dissociation curve as PPCO2 increases?
The further the curve shift to the right (more dissociation)
What happens to the oxygen dissociation as partial pressure of carbon dioxide (ppCO2) decreases?
At a lower ppCO2 (at the same ppO2) haemoglobin has a higher affinity for oxygen
This means oxygen associates with haemoglobin more quickly at alveoli
How does the size of an organism change its haemoglobin affinity for oxygen?
Smaller mammals have a higher surface area to volume ratio
This causes them to lose heat more quickly - high metabolic rate (high O2 demand)
Hb has a lower affinity for oxygen = unloading to meet demand
Shift the curve to the right
How does living underground or at high altitude affect oxygen dissociation?
Hypoxic environments (lower ppo2)
- Hb has a higher affinity for oxygen due to its limited supply
- Oxygen loads more quickly for sufficient O2
Curve shifts to the left
How do high activity levels affect oxygen dissociation?
Active mammals have a higher O2 demand so HB has a lower affinity for oxygen causing it to unload to respiting muscles
Curve shifts to the right
What is tissue fluid?
The solution/watery liquid surrounding/bathing cells in their immediate environment
How is tissue fluid formed.?
Formed from blood plasma that moves out of the capillaries via fenestra (endothelial pores)
- made of substances small enough to exit through fenestar
What is the function of tissue fluid?
Its function is to supply tissues with essential solutes (glucose, amino acids and ions) in exchange for waste products (urea and carbon dioxide)
What is tissue fluid made from?
It is made from small molecules that leave the blood plasma
Eg. Oxygen, water, glucose, ions
But larger molecules like plasma proteins and blood cells remain in the capillary
What is hydrostatic pressure?
The outwards pressure exerted by a liquid (blood) inside the capillary
AKA- Blood pressure
What is hydrostatic pressure like at the arteriole end of the capillary?
HIGH hydrostatic pressure created by contraction of the hearts ventricles
What is hydrostatic pressure like at the venule end of the capillary?
LOW hydrostatic pressure
- Friction
- Formation of tissue fluid
What factors cause a reduction in hydrostatic pressure at the venous end of the capillary?
Friction with blood vessel walls causes blood to flow more slowly reducing its pressure
Water and small soluble molecules leave blood reducing its volume and therefore its pressure
How does friction reduce the hydrostatic pressure at the venous end of the capillary bed?
Friction with blood vessel walls causes blood to flow more slowly reducing its pressure
How does the formation of tissue fluid lead to a lower hydrostatic pressure at the venous end of the capillary bed?
Tissue fluid is formed from the filtration of water and small soluble molecules causing a reduction in volume of the blood therefore its pressure
What is osmotic pressure?
The inwards force caused by a water potential gradient (higher water potential outside the capillary bed than inside)
When water moves out of the capillary bed due to a high hydrostatic pressure what happens to the water potential?
The water potential in the capillary become more negative as water has left the capillaries to form tissue fluid
What is osmotic pressure like at the arterial end of the capillary bed?
LOW osmotic pressure as there is a higher water potential inside the capillary (water can’t move against the water potential gradient and into the capillary)
What happens to osmotic pressure at the venous end of the capillary bed?
The osmotic pressure is HIGH as tissue fluid creates a higher water potential outside the capillary and the high concentration if plasma proteins in the capillary causes a low water potential.
This creates a steep water potential gradient for 90% of the tissue fluid to return to capillary by osmosis
Why does osmotic pressure increase towards the venous end of the capillary?
Water and small soluble molecules leave - plasma proteins become more concentrated at the venous end
Creates a steep water potential gradient to increase osmotic pressure.
What happens to the remaining 10% of tissue fluid which isn’t reabsorbed into the capillary bed (at venule end)?
It enters the lymphatic vessel as lymph
What is the purpose of the lymphatic system?
Carries LYMPH (clear liquid) to remove waste products - prevent swelling by water retention
Lymph nodes prevent entera de of foreign materials and produce antibodies
One way drainage - passes excess fluid back into the circulatory system near the heart
Where does the excess 10% tissue fluid re-enter the circulatory system?
Drains back into the blood via ducts near the heart
By travelling through lymphatic vessels
What are the specific risk factors associated with cardiovascular disease ?
Age
Smoking
High fat diet
Obesity
High blood pressure
Lack of exercise
Genetic predisposition
Why is age a risk factor for cardiovascular disease?
arteries will natural harden and deteriorate with age
Why is smoking a risk factor for cardiovascular disease?
Carbon monoxide reduces the amount of oxygen transported in the blood - so less O2 available for tissues causing myocardial infarction
Smoking decreases antioxidants in blood which protect cells from damage- can lead to atheroma
Why is a high fat diet a risk factor for cardiovascular disease?
higher levels of “bad” cholesterol which can build up in arterial walls - causes fatty deposits which form atheroma
High saturated fat increases cholesterol and high salt increases blood pressure
How can obesity act as a risk for cardiovascular disease?
It deposits fat between internal organs (visceral)
Why is high blood pressure a risk for cardiovascular disease?
It accelerates arteriole damage due to excessive pressure
Why is a lack or exercise a risk for cardiovascular disease?
It weakens the heart muscle / poorer circulation of blood
