Unit 2.3a - Adaptations for transport in animals Flashcards
The transport of what is covered in this unit?
Oxygen to the cells for aerobic respiration
Nutrients from food from digestive system to other cells
Features of a transport system in animals
A suitable medium to carry materials through the system (e.g - blood)
A pump such as the heart for moving blood through the blood vessels
Valves to maintain the flow in one direction
(In some)
A respiratory pigment that binds t oxygen to transport it around the body (e.g - haemoglobin) - increases the volume of oxygen that can be transported (in vertebrates and some invertebrates- not in insects)
A system of vessels with a branching network to distribute the transport medium to all parts of the body
Why is oxygen transported to cells?
For aerobic respiration
Why do animals get their nutrients and where are they transported to and from?
From food
From digestive system to other cells
Purpose of the heart
Pump blood through blood vessels
What is blood in a transport system?
A suitable medium to carry materials through the system
What type of animals have expiratory pigments in their transport system?
Vertebrates and some invertebrates
(Not in insects)
Why are open circulatory systems known as this?
Blood LEAVES the vessels
What is the ‘heart’ of an insect and where is it?
Dorsal vessel
Runs the length of its body
Dorsal vessel
‘Heart’ of an insect
Draw and label a dorsal vessel in an insect
(See notes)
What type of circulatory system do insect have?
Open circulatory system
Name a type of animal with an open circulatory system
Insects
What’s the ‘blood’ of an insect known as?
Haemolymph
What does the haemolymph of insects contain?
Nutrients
Glucose
Amino acids
Vitamins/mineral
Water
Why does haemolymph in insects contain its nutrients and minerals etc?
From digested food
What is it worth noting that the haemolymph of an insect does NOT contain and why is this the case?
Oxygen (or respiratory pigment)
Insect gas exchange has trachioles that exchange gas straight from the air to the cells
(No need to transfer it from the blood into cells around the body)
Where are the organs situated in an insect?
Haemocoel
Describe the process occurring in open circulatory systems in insects
Blood is pumped at low pressure by a long, dorsal tube shaped heart running the length of the body
Blood is pumped out of the heart into spaces collectively called haemocoel (where the organs are situated) within the body cavity
Blood bathes the tissues directly where exchange of materials takes place
Blood slowly returns to the heart
Valves and waves of muscle contraction move blood forward to the head region where the open circulation has started again
Where is the haemocoel n an insect?
Within this body cavity
How much control do insects have over direction of circulation?
Little control
Is the blood of an insect red? Why?
No
It doesn’t contain a respiratory pigment like haemoglobin
Closed circulatory system
Blood doesn’t leave the vessels
Transports materials to exchange surfaces
Give an example of a creature which has a closed circulatory system
Earthworm
What type of circulatory system does an earthworm have?
Closed circulatory system
Draw a diagram to represent the closed circulatory system of an earthworm
(See notes)
Where are the capillaries of an earthworm situated?
Throughout the whole worm
Pseudoheart
Thickened muscular blood vessels in worms
Single circulation
Blood moves through the heart once in its passage around the body
Describe the process occurring in the closed circulatory system of an earthworm
Blood moves by the pumping action of the pseudohearts
Blood is pumped at high pressure by a series of 5 muscular pseudohearts
Blood circulates in a continuous system of blood vessels - dorsal (top) and ventral (bottom) which run the length of the body
What does the continuous system of blood vessels in an earthworm consist of?
Dorsal (top)
Ventral (bottom)
Run the length of the body
Describe the blood flow in earthworms (closed circulatory system)
Fairly rapid
Controlled in terms of direction of flow
What happens to the organs and tissues of an earthworm with its closed circulatory system?
Organs and tissues are NOT bathed directly by the blood, but by tissue fluid which seeps out of thin-walled capillaries
What is the direction of flow of blood controlled by in an earthworms circulatory system?
The valve
Describe the direction of blood flow in an earthworm’s circulatory system and explain this
Blood flows in 1 direction only
Prevents backflow to the heart
What type of circulatory system does a fish have?
Single
Draw a diagram to represent the single circulation system in a fish
(See notes)
Describe the process of single circulation in a fish
Ventricle of the heart pumps deoxygenated blood to the gills
Well developed capillary network spread throughout the body reduces its pressure
Oxygenated blood is carried to the tissues
Deoxygenated blood returns to the atrium of the heart
Blood moves to the ventricle
Circulation starts again
Where is the well-developed capillary network in a fish?
Spread throughout its body
What’s the purpose of the valves the heart?
ensure that the blood doesn’t backflow to the heart
What happens when valves in the heart are open?
blood goes to the heart
What happens when valves in the heart are closed?
prevents blood going back to the heart
What is responsible for ensuring that blood doesn’t backflow to the heart?
valves
Double circulation
the blood passes through the heart tissue twice in its circuit around tha body
draw a diagram representing single, closed circulation
(see notes)
draw a diagram representing double circulation
(see notes)
What does systematic circulation move between?
the heart and tissues
What does pulmonary circulation move between?
the heart and lungs
give examples of creatures that have single, closed circulation
fish
annelids
annelids
worms, for example
give examples of creates that have double circulation
mammals
birds
reptiles
name an animal with open circulation
insects
Do mammals, reptiles and birds have open or closed cirulation?
closed
name a group of animals that have only slightly different circulatory systems compared to birds and mammals
amphibians
(some reptiles)
what’s different about the circulatory system of amphibians and some reptiles compares to those of birds and mammals?
3 chambers
what type of animals have 3 chambers in their circulatory systems?
amphibians (and some reptiles)
describe the blood in the circulatory system of amphibians
mix of oxygenated and deoxygenated
where does oxygenated blood come from?
from the lungs
where does deoxygenated blood come from?
the body
why do amphibians have a mix of oxygenated and deoxygenated blood?
ventricle is not split completely
what does the fact that amphibians blood is a mix of oxygenated and deoxygenated blood mean for the blood?
lowers the O2 concentration of the blood before being pumped around the system
why do amphibians have lower O2 concentration in their blood?
amphibians exchange gas through both their lungs and their outer skin
they don’t RELY on their lungs, so they’re less efficient, but still sufficient for what they need
why do amphibians have
advantages of double circulation
separate circulation to the body and the lungs
oxygenated and deoxygenated blood is separate
high blood pressure is maintained to the body tissues (systematic circulation) which leads to greater oxygenation of tissues
lower blood pressure to the lungs (pulmonary circulation) which prevents hydrostatic pressure forcing tissue fluid (plasma) into the alveoli - accumulation of tissue fluid in the alveoli would reduce gas exchange efficiency
what is blood pumped by and why?
a muscular heart at high pressure
to give a rapid flow rate through blood vessels
why is blood pumped at high pressure?
to give a rapid flow rate through blood vessels
what’s the order of the blood vessels that blood travels through in the circulatory system of mammals?
arteries –> arterioles –> capillaries –> venules –> veins
arterioles
thin arteries
venules
tiny veins
where do arteries take blood?
away from the heart
what particular adaptation do the arteries have and why?
thick, muscular walls to withstand the blood’s high pressure, derived from the heart
what type of blood do the arteries transport and what’s an exception to this?
oxygenated
pulmonary arteries
what type of blood do the arteries transport and what’s an exception to this?
oxygenated
pulmonary arteries
which two types of blood vessels have the same basic 3 layer structure, just in different proportions?
arteries and veins
what’s different between the 3 layered structure of the arteries vs the veins?
the proportions
draw and label the tissues in both the arteries and veins
(see notes)
what has a larger diameter in total - the arteries or the veins?
arteries
tunica intima
single layer of endothelium
in some arteries, it is supported by elastin-rich collagen
smooth lining, reducing friction, producing minimal resistance to blood flow
draw the cells in the tunica intima
(see notes)
tunica externa
fibrous proteins like collagen resist overstretching
tough protective layer
tunica media
thick, muscular layer
contains smooth muscle and elastic connective tissue
what’s thicker - the tunica media of the artieries or veins?
arteries
what’s the purpose of the smooth muscle in the tunica media?
regulate blood flow and maintain blood pressure as blood is transported further from the heart
what do the tunica media do in artieries?
contract to change the diameter of the arteries
what’s thicker - the walls of the arteries or veins?
arteries
why are the walls of the artery much thicker than the walls of the veins?
blood in the artery is in much higher pressure (blood from the heart)
need to be able to handle a change in pressure
compare the flow rate and pressure of the veins compared to the arteries
in the veins, it’s lower
what has the largest diameter lumen - the veins or the artieries?
veins
lumen
where liquid flows through a blood vessel
why is the lumen of the veins thicker than in the arteries?
needs to be wider to reduce resistance to flow, allowing blood to flow easily under low pressure
how does blood move in the veins above the heart?
blood returns to the heart via gravity
how does blood in the veins that aren’t above the heart?
by the pressure from surrounding molecules
what do veins have along their length?
semi-lunar valves
what have semi-lunar valves along their length?
veins
what do semi-lunar valves in the veins do?
prevent back flow - ensure that flow only occurs in 1 direction
are semi-lunar valves present in the artieries?
no
only in the base of the aorta and the pulmonary artery
what can happen if the semi-lunar valves of the veins are faulty?
varicose veins
heart failure
what do veins run through?
large muscle groups (e.g - legs)
why do veins run between large muscle groups such as the legs?
when we move - muscles contract
push on the walls of veins
helps blood flow towards the heart
maintains pressure in the blood
(this is why you shouldn’t sit still for too long)
why shouldn’t we sit still for too long?
bad for circulation
what can happen if we sit still/stand up for too long? why does this happen?
can faint
restores blood flow to brain
what happens in the capillaries?
exchange
what do capillaries form? what is this known as?
a vast network that penetrates all the tissues and organs of the body (except the cornea and cartilage)
the capillary bed
in which organs and tissues are there no capillaries?
cornea
cartilage
the capillary bed
a vast network that penetrates all the tissues and organs of the body
Describe how the capillaries have adapted for their function for gas exchange
very fine blood vessels (reduces diffusion distance for gas exchange)
very numerous (larger surface area for gas exchange)
inly a single cell endothelium layer as its walls
take blood as close as possible to the cells - rapid exchange of substances between blood and cells
tiny gaps (fenestrations) between individual cells allow some components of blood to leak out into the surrounding tissue (the tissue fluid) and bathe them
permeable to water and dissolved substances like glucose, amino acids, water, dissolved gases (O2)
What’s the name of the tiny gaps between individual cells on the capillaries and what’s their purpose?
fenestrations
allow some components of blood to leak out into the surrounding tissue (this its the tissue fluid) and bathe them
what’s the wall of a capillary?
single cell endothelium layer
what are the capillaries permeable to?
water and dissolved substances like
glucose
amino acids
dissolved gases (O2)
Draw and label a capillary
(see notes)
Can blood vessels pass through the pores of capillaries? why?
no, they’re too large
what are the capillaries adapted for compares to other blood vessels?
exchange
others - transfer blood a long distance through the body
what does the heart consist largely of?
cardiac muscle
cardiac muscle
a specialised tissue wth myogenic contraction
myogenic contraction
contracts and relaxes rhythmically within the muscle cells themselves and is independant on nervous or hormonal stimulation
what is the heart rate modified by in life?
nervous and hormonal stimulation
does the cardiac muscle ever tire? what’s this unlike?
no, unlike voluntary muscles
is the structure of the heart the same in all mammals?
pretty much
draw and label the external structure of the mammalian heart, including the direction of blood flow stating whether its oxygenated or deoxygenated
(See notes)
What does the Vena Cava do in the heart?
transports deoxygenated blood from systematic circulation in tissues to the right side of the heart
what does the aorta do in the heart?
the main artery that carries blood to the systematic circulation
what are both parts of systematic circulation?
vena cava and aorta
what are the vena cava and aorta both parts of?
systematic circulation
what do the coronary arteries do?
carry blood FROM the heart TO the heart
the hearts own blood supply that carry oxygenated blood to the cardial muscles in the heart
where do the coronary arteries carry blood to in the heart?
the cardial muscles
what could the heart not function without?
the blood supply of the coronary arties
where do the coronary arteries originate and what do they transport?
the base of the aorta
transport oxygenated blood
where is the heart located in the body?
in the middle of the thorax, behind the lungs
why do lots of people think that the heart is to the left?
you can feel your heartbeat on the left, as its the most muscular side of the heart that contracts most strongly
which artieries are at risk of getting blocked and why?
coronary arties
very thin
what feature of the coronary arties imposes a risk to them and what is this?
very thin
can get blocked
in which circumstance could the coronary artery get blocked?
with heart disease
what can happen when the coronary arteries get blocked?
blood supply to the heart is interrupted
part of the tissue can die
heart attack
what type of fats impose a risk to the coronary arteries and why?
saturated fats
build up on the walls of coronary arteries
blood supply to the heart is interrupted
draw and label the internal structure of the heart, including direction of blood flow and whether its oxygenated or deoxygenated
(See notes)
what are the 4 chambers in the heart?
top - right and left atrium
bottom - right and left ventricles
describe the process that deoxygenated blood takes as it returns to the heart before returning to the lungs
returns through the Vena Cava
enters the right atrium
once full of blood, the wall of the atrium contracts
tricuspid valve is forced open due to the increase in blood pressure, allowing blood to enter the right ventricle
right ventricle full of blood, the wall of the ventricle contracts from the apex upwards
this forces the blood upwards
the tricuspid valve shuts and the semi-lunar valve at the opening to the pulmonary artery is forced open
blood is transported to the lungs
describe the process that oxygenated blood takes as it returns to the heart before returning to systematic circulation
returns to the heart via the pulmonary vein
left atrium fills with blood and then contracts
bicuspid valve is forced open, allowing blood to fill the left venticle
once the ventricle is full, it contracts and forces blood upwards
this increase in blood pressure closes the bicuspid valve and forces the semi-lunar valve, at the opening of the aorta, open
blood is forced into the aorta and onwards to the body at high pressure
re-enters systematic circulation
where does deoxygenated blood return to?
the lungs
where does oxygenated blood return to?
systematic circulation
what do all of the events in the heart happen in and why?
in sequence
ensure that blood flows efficiently
what do all of the events in the heart happen in and why?
in sequence
ensure that blood flows efficiently
Which ventricle in the heart is thickest and why?
Left ventricle
Produce a higher blood pressure in order to pump blood through the systematic circulation
Systematic circulation has to transport blood to ALL parts of the body
Draw and label the valves of the heart from above
(See notes)
How can we identify the tricuspid valve?
3 cusps in the valve
How do we identify the bicuspid valve?
2 cusps in the valve
Where does the coronary artery join on to the heart and why?
The aorta
To provide the heart with oxygenated blood
What’s the other name for the tricuspid valve?
Right atrioventricular valve (A.V)
What’s the other name for the Bicuspid valve?
Left Atrioventricular valve (A.V)
How do the 2 sides of the heart contract relative to eachother?
Contract at the same time
What needs to be true for the contractions of both sides of the heart and why?
Need to be coordinated in order to be efficient
What are the 3 main parts of the cardiac cycle?
Atrial systole
Ventricular systole
Diastole
The Cardiac cycle
The contractions of the heart that form the heart beat
Atrioventricular valves
Tricuspid an Bicuspid valves
Describe atrial systole in the cardiac cycle
Muscle in walls of the ventricles relax
Atrial walls contract
Pressure in the atria increases
Atrio-ventricular valves open
Blood fills the ventricles
Describe ventricular systole in the cardiac cycle
Muscle in walls of the ventricle contract
Blood pressure in the ventricles increases to be greater than atrial pressure
Atrio-ventricular valves close
Pressure in the ventricles increases above the aerial pressure - aortic and pulmonary valves open
Blood leaves the ventricles into the pulmonary arteries and aorta
Describe diastole in the cardiac cycle
Muscle in walls of the atria and ventricles relaxes
Pressure in the atria and ventricles decreases to lower than the pressure in the arteries
Aortic and pulmonary valves close
Blood from the Vena Cava and Pulmonary veins fills the atria
What decides whether a valve is open or shut?
Blood pressure either side of a valve
Draw and label a pressure against time graph for a heat beat
(See notes)
What goes long the axes for a graph of a heartbeat?
Time against pressure
Semi lunar valves
Aortic and pulmonary valves
What are the sounds that can be heard when listening to a heartbeat?
“LUB” and “DUB”
When does the “LUB” sound occur when a heart beats?
As the atrioventricular valves close
When does the “DUB” sound occur as the heart beats?
As the semi-lunar valves close
Which is louder - the “LUB” of the atrioventricular valves closing or the “DUB” of the Semi Lunar valves closing?
The “LUB” of the atrioventricular valves
What are the 4 key points to label on a pressure against time graph of a heart (in order)?
Atrioventricular valves close
Semi lunar valves open
Semi lunar valves close
Atrioventricular valves open
How do we measure the beats per minute of a heart from a pressure against time graph?
Measure the same point between 2 beats = time for 1 beat
60/answer = beats min^-1
How is high pressure maintained in the aorta?
Tunica media contains elastic fibres which allow it to expand and stretch during an increase in pressure (can also contract to help push blood out)
Aorta has a narrow lumen and thick walls
Is never empty of blood as the aortic valve restricts blood from flowing back to the ventricle
Which tissue layer in the aorta allow it to expand? Why?
Tunica media
Contain elastic fibres
Why is the aorta never empty of blood?
The aortic valve restricts blood from flowing back to the ventricle
Where are the semi-lunar valves situated?
At the base of the arteries
What word can be used to describe cardiac muscle?
Myogenic
Myogenic
Beat on its own, without nervous stimulation
Where is the contraction from the myogenic cardio muscles stimulated from?
From within the cardiac muscle itself
What does myogenic cardiac muscle of the heart NOT require?
Impulses from nerves to make it contract
What do cardiac cells do?
Contract and relax rhythmically by themselves
What can individual heart cells not be allowed to do and why?
Beat at random
The heart wouldn’t function as a pump
Why can’t individual heart cells be allowed to beat at random?
The heart wouldn’t function as a pump
What does the heart have its own?
Built in controlling and coordinating systems
What does the controlling and coordinating system of a heart to control the heart beat consist of?
Nerve fibres and tissues
What do nerve fibres and tissues control in the heart?
The timings of the events of the cardiac cycle
Draw and label parts of the heart that are responsible for initiating and controlling the cardiac cycle
(See notes)
Name the 4 main parts of the heart responsible for initiating and controlling the cardiac cycle
Sinoatrial node (SAN)
Atrioventricular node (AVN)
Bundle of His
Purkinje fibres
Which part of the heart is often exerted to as the “pacemaker” and why?
The sinoatrial node (SAN) as it initiates the cardiac cycle
What is the sinoatrial node of the heart often referred to as and why?
The pacemaker of the heart as it initiates the cardiac cycle
Septum of the heart
Wall that separates the 2 chambers of the heart
Wall that separates the 2 chambers of the heart
Septum
What IS the sinatrial node (SAN) and what does it do?
A specialised path of muscle in the wall of the right atrium
Initiates the cardiac cycle
What does the sinoatrial node (SAN) cause to occur in the heart? Explain
Initiates the cardiac cycle
A wave of excitation/a wave of depolarisation spreads from the SAN across the 2 atria
The atria depolarise
The two atria start to contract
The wave stops at the base of the atria and is prevented from recant the ventricles by a layer of connective tissue
Where is the wave caused by the SAN stopped and why?
At the base of the atria
Prevented from reaching the ventricles by a layer of connective tissue
How does the sinoatrial node initiate the cardiac cycle?
A wave of excitation/a wave of depolarisation spreads from the SAN across the 2 atria
After the wave caused by the SAN has caused the 2 atria to contract, what happens next to control the cardiac cycle? Explain
The wave reaches the atrioventricular node (AVN) and is conducted along the bundle of His (through the septum) to the apex of the ventricles
The bundle of His divides into the Purkinje fibres which conduct the wave up through the muscle in the ventricle walls
Ventricles are depolarised
Ventricles are stimulated to contract
Where does the wave of excitation go following the sinoatrial node?
Th atrioventricular node (AVN)
Where is the bundle of His in the heart?
Through the septum
What does the bundle of His divide into?
Purkinje fibres
What is the final stage of how the cardiac cycle is controlled?
There is a delay before the ventricles contract
Contraction starts from the base (apex) and moves upwards to push blood through the arteries
After re-polarisation of the ventricle
Why is there a slight delay of the wave of electrical activity at the AVN?
Ensures that the atria are emptied before the ventricles contract
What does ECG stand for?
Electrocardiogram
Electrocardiogram (ECG)
A trace (or graph) that shows the electrical output of the heart
How can an Electrocardiogram be obtained?
Electrodes can be placed on the skin of the chest to pick up an electrical output from the heart
What does an Electrocardiogram measure?
The electrical activity taking place in the heart as it beats
What are the benefits of using Electrocardiograms?
Quick, effective and important means of collecting information to diagnose problems affecting the heart
How is electrical activity displayed as an electrocardiograph?
By means of a chart recorder
What is electrical activity taking place in the heart muscle as it beats related to?
The electrical impulses that pass through the heart tissue
Draw and label a typical Electrocardiogram
(See notes)
How do we calculate the heart rate from an Electrocardiogram?
60
——
Length of cardiac cycle (s)
What happens at the P wave of an Electrocardiogram?
SAN begins contraction of atria
(Description of control of cardiac cycle)
What happens at the QRS complex of an Electrocardiogram?
Start of ventricular systole
(Description of control of cardiac cycle)
What happens at the T wave of an Electrocardiogram?
Diastole -recovery wave
(Description of control of cardiac cycle)
Give an example of an Electrocardiogram giving information about the health of a heart
Longer pause between P and QRS complex = problem in the tissue that gives out the wave of excitation
Purpose of blood in animals
Transport nutrients and oxygen from the gas exchange surface to the tissues where cells require oxygen for respiration
Which animals don’t have the same purpose for blood?
Insects
How do we observe the contents of blood?
Withdraw blood and place in a tube
Treat with an anti-clotting agent (e.g - heparin)
Centrifuge
Example of an anti-clotting agent
Heparin
Draw and label the contents of a test tube after the centrifugation of blood
(See notes)
What percentage of blood is plasma?
50%
What are the formed elements in blood?
Huffy coat
Erythrocytes
Where are the arythrocytes in the tube following the centrifugation of blood? Why?
Cells are denser, so they settle at the bottom of the tube
Erythrocytes
Red blood cells
Word for red blood cells
Erythrocytes
What are the 3 components of blood?
Plasma
Buffy coat
Erythrocytes
What is the Buffy coat in blood?
White blood cells
Name 3 types of white blood cells
Neutrophils, monocytes, lymphocytes
What do white blood cells do?
Protective cells that protect against infection
What’s the plasma in blood?
The fluid part that cells flow through
It also distributes heat
Which part of blood distributes heat?
The plasma
What does the plasma of blood mostly consist of?
Water
Plasma proteins
Electrolytes
What is the main content of plasma?
Water
Name the electrolytes that mostly make up plasma in blood
Na+ and Cl-
What are some other components as opposed to the main ones in plasma?
Nutrients
Hormones
Wastes
Blood gases
Give 2 examples of nutrients in blood plasma
Glucose and amino acids
Give 2 examples of hormones in blood plasma
Cortisol
Thyroxine
Give an example of a waste product in blood plasma
Urea
Give 2 examples of blood gases in blood plasma
CO2, O2
What are placelets in blood?
Parts of cells that cause the clotting of blood
How do placelets cause the clotting of blood?
Produce the protein fibrinogen when an injury occurs for clotting
This fibrous net stops the flow of blood
Wht produces the protein fibrinogen? When?
Placelets in blood when forming a clot
What are the 5 adaptations of erythrocytes for their purpose?
Biconcave discs
Very small
No nucleus
Biconcave is thin
Cytoplasm packed with haemoglobin
Why is the shape of erythrocytes called a Biconcave disc?
Concaves form on the top AND base
(“Bi”concave)
Why is the Biconcave disc shape of erythrocytes advantageous to them?
Increases the surface area to volume ratio
Can carry more oxygen
How would you describe the shape of erythrocytes?
Biconcave discs
How big are erythrocytes?
Very small
(About 7 micrometres)
Why is it advantageous to erythrocytes that they’re so small?
Large surface area due to there being large amounts of them
= Large surface area for oxygen absorption
Also
Large surface area to volume ratio
Short diffusion pathway
What’s an additional adaptation to the shape of an erythrocyte and why is this advantageous to it?
Biconcave is thin
=short diffusion pathway
What does haemoglobin do?
Binds to oxygen to transport it around the body
What is used to estimate the number of red blood cells per mm^-3 of a sample?
Haemocytometer grid
Haemocytometer grid
A glass microscope slide with a grid on it
Draw where the samples for red blood cells are usually taken on a Haemocytometer grid
(See notes)
How do we estimate the number of red blood cells in a mm^-3?
- Count the red blood cells in each small grid
- Calculate the mean number of cells from the grids
- Number of cells
————————
Volume of small square
What are we working out when estimating the numbers of red blood cells?
The amount of red blood cells per mm^-3
What type of protein is haemoglobin?
Quaternary globular protein
What is the structure of haemoglobin like due to it being a globular protein?
Compact
What is haemoglobin made up of?
4 polypeptide chains
What are the 4 polypeptide chains in haemoglobin?
2 alpha
2 beta
What does every polypeptide in haemoglobin contain?
A haem group
Describe the haem groups of hemoglobin
Non-protein
What does each haem group contain in their structures?
An atom of Fe++
Which part of haemoglobin contains an atom of Fe++ each?
Haem group of each polypeptide
What attracts oxygen to haemoglobin?
The Fe++ atom in the haem groups
What do the Fe++ atoms in the haem groups of haemoglobin do?
Attract oxygen
What can every haem group in haemoglobin bind to?
1 molecule of oxygen
How many atoms of oxygen are in each haemoglobin? Why?
8
(Every haem group can bind to 1 MOLECULE, which contain 2 atoms each)
Affinity
The degree to which 2 molecules are attracted to each other
What does haemoglobin have towards oxygen?
An affinity
What can haemoglobin’s affinity for oxygen depend upon?
The O2 concentration in the environment
What’s the % maximum oxygen that a sample of haemoglobin can carry?
100%
Describe haemoglobin combined with the maximum amount of oxygen
Saturated
What shape does the oxygen dissociation curve for haemoglobin have?
S shape
What’s the name for the graph showing the % saturation of haemoglobin against the partial pressure of oxygen?
Oxygen dissociation urge for haemoglobin
What goes along the axes of the oxygen dissociation curve for haemoglobin?
X = partial pressure of oxygen
Y = % saturation of haemoglobin
How many O2 molecules are bound to haemoglobin at 100% saturation?
4
How many O2 molecules are bound to haemoglobin at 75% saturation?
3
How many O2 molecules are bound to haemoglobin at 50% saturation?
2
How many O2 molecules are bound to haemoglobin at 25% saturation?
1
Describe the % saturation of haemoglobin at lower partial pressures of O2
Low
What’s the potential pressure of O2 when the % saturation of haemoglobin is low?
Low
What does it mean if the % saturation of haemoglobin is low?
It’s combined with very little O2
Describe the affinity haemoglobin has for oxygen when it’s combined with very little O2
Low
When does haemoglobin have a low affinity for oxygen?
When it’s combined with little oxygen
What does the oxygen dissociation curve for haemoglobin demonstrate?
How haemoglobin behaves at different partial pressures of oxygen
Partial pressure
The pressure a gas exerts on the container its in
Why do we use partial pressure to measure the amount of oxygen as opposed to its concentration?
It’s a gas
How does the % of oxygen differ at higher altitudes than sea level?
The same
How is the air different at high altitudes and what does this mean?
The air is thinner as molecules are further apart
It’s harder to get O2 into the body
How is the partial pressure of oxygen different at higher altitudes than at sea level?
It’s lower at higher altitudes
What does the body do at higher altitudes?
Builds new red blood cells
How ones the affinity of haemoglobin for oxygen change as more oxygen is bound?
Once 1 molecule of oxygen is bound, the affinity of haemoglobin for oxygen increases
What affect does haemoglobin having an increased affinity for oxygen have?
It makes it easier to bind to other molecules
Why does having more oxygen bound to haemoglobin increase its affinity for oxygen?
When O2 binds, the quaternary structure of haemoglobin changes, increasing the affinity of the heam groups for oxygen
What effect does haemoglobin’s increased affinity for oxygen have on the oxygen partial pressure required?
Increased affinity for oxygen = less oxygen partial pressure required
How does the 4th haem group bind to oxygen?
Only at a fairly high partial reassure
Why does the 4th haem group only bind to oxygen at a fairly high partial pressure?
3/4 haem groups are already filled
The probability of an O2 molecule colliding with the 4th haem group is low
Explain the flat region of the oxygen dissociation curve for haemoglobin
At high partial pressures of oxygen, a drop in partial pressure does not lead to a corresponding drop in haemoglobin saturation
Describe the oxygen released by haemoglobin at high partial pressures
Haemoglobin will not release oxygen readily
Name somewhere in the body with high partial pressures
The lungs/alveoli
What happens to the partial pressure of oxygen as red blood cells make their way into body tissues? Why?
It decreases
Tissues are carrying out aerobic respiration
What is occurring as we move down the curve and the partial pressure of oxygen decreases?
Red blood cells make their way into body tissues
They carry out aerobic respiration = partial pressure of oxygen decreases
What does tissues carrying out aerobic respiration do to the partial pressure of oxygen?
Decreases it
Explain the linear region of the curve on an oxygen dissociation curve for haemoglobin
At lower partial pressures of oxygen (e.g - body tissues)
A small drop in oxygen partial pressure leads to a large decrease in haemoglobin saturation
=oxygen is readily released into the tissue
Where in the body has low partial pressures of oxygen?
Body tissues
When is oxygen readily released into tissues?
At lower partial pressures of oxygen
What does unloading O2 molecules from a haemoglobin molecule do to its structure?
Changes the quaternary structure
What does changing the quaternary structure of haemoglobin when unloading O2 molecules from it do to it?
Decreases the O2 affinity of the remaining haem groups
What isn’t always released under normal conditions for haemoglobin?
The last O2 molecule
Why is the last O2 molecule not always released from haemoglobin?
Partial pressures aren’t low enough
Oxygens affinity would be too high
In which circumstance would the last O2 molecule be unloaded from haemoglobin?
In active tissue
Why would the last O2 molecule be unloaded for active tissues?
Higher demand for O2
Very low O2 partial pressure
Haemoglobin rapidly unloads O2 to the tissue
Give an example of a tissue that has a very low O2 partial pressure?
An active tissue
Why does blood pressure decrease so rapidly in the capillaries?
More vessels = larger c.s area
Smaller = more friction
Adaptation of the arteries for their function
Thick, muscular walls to withstand blood’s high pressure, derived from the heart
Adaptation of veins for their function
Large diameter lumen - needs to be wider to reduce resistance to flow, allowing blood to flow easily under low pressure
Adaptation of capillaries for their function
Very fine blood vessels, that are very numerous to give a large surface area for gas exchange
Which parts of an Electrocardiogram (ECG) represent which parts of the cardiac cycle?
P wave - atrial systole
QRS complex - ventricular systole
T wave - diastole
When does haemoglobin have a low affinity for oxygen and why is this useful?
High affinity for oxygen at low partial pressures of oxygen, which is exactly where it’s needed
Draw and label a graph to show the usual partial pressure of O2 in…
The lung capillaries
The tissue capillaries at rest
The tissue capillaries during strenuous activity
(See notes)
Describe the partial pressure of oxygen in the lungs
High
Describe the saturation of haemoglobin with O2 in the lungs
95%-98%
What does haemoglobin’s saturation with O2 never reach?
100%
Describe how much oxygen haemoglobin is combined to in the lungsA
Almost every haemoglobin molecule will be combines with 8 atoms of oxygen
Describe the partial pressure of oxygen in tissues that are actively respiring
Low partial pressure of oxygen
Describe the saturation of haemoglobin with oxygen in actively respiring tissues
20-25% saturated (1/4 of possible oxygen)
If haemoglobin is only 20-25% saturated with oxygen in respiring tissues, what’s happening to the rest of the oxygen?
It’s released from the haemoglobin and diffuses into cells for respiration
What’s the effect of CO2 on the affinity of haemoglobin for oxygen?
The higher the concentration/partial pressure of CO2 —> the lower the affinity of haemoglobin for oxygen
What does the fact tat haemoglobin has a lower affinity for oxygen in a higher concentration of CO2 mean?
More O2 is released when CO2 is present
What do we call the fact that more O2 is released when CO2 is present?
The Bohr effect
The Bohr effect
More O2 is released when CO2 is present
Why is the Bohr effect beneficial to tissues?
Allows haemoglobin to release oxygen even more readily when it reaches respiring tissues (which have CO2 as their waste product)
In which direction does the Bohr effect shift the dissociation curve?
To the right
Describe how moving the dissociation curve to the right with the Bohr effect changes the O2 haemoglobin interacts with
Less ready to pick O2 up
More ready to release O2
Venous partial pressure of O2
30-40mmHg
Arterial partial pressure of O2
80-100 mmHg
At the same partial pressure of oxygen, how does haemoglobin differ for respiring tissues as opposed to in the lungs? Why?
Haemoglobin is less saturated with O2 at the same partial pressure for respiring tissues
More is released
Effect of an increased temperature on…
Haemoglobin’s affinity for oxygen
The dissociation curve
Lower affinity for oxygen
Curve moves right
The effect of increased pH on…
Haemoglobin’s affinity for oxygen
The dissociation curve
Higher affinity for oxygen
Curve moves left
Where does a foetus get its O2? Why?
From the mother’s blood - their own lungs are full of liquid, not air
Why does foetal haemoglobin need to be different to that of the mother?
The mother’s haemoglobin will be binding to its own oxygen, so the foetal haemoglobin needs to be able to obtain some
How is foetal haemoglobin different to the parental haemoglobin?
It’s a different type that has a higher affinity for oxygen than adult haemoglobin
Why does foetal haemoglobin have a higher affinity for oxygen than adult haemoglobin?
2 of haemoglobin’s polypeptide chains are altered
How does the blood of a foetus interact with that of the mother?
Flow closely together in the placenta, but rarely mix
Where does foetal blood flow?
In the placenta
Which mechanism is used to ensure that a foetus receives oxygen from the mother’s blood?
Counter-current flow
Oxygen diffuses to foetus capillaries from the mother’s blood
Give 2 examples of organisms living in low partial pressure environments
Lugworms
Llamas
How is a lugworm’s haemoglobin different to ours and why?
Has a higher affinity for oxygen as the U-shaped burrows they live in in the sand has a very low oxygen partial pressure
How is a llama’s haemoglobin different to ours and why?
Higher affinity for oxygen as they live in environments of high altitude like the Andes
What is different in llamas, for example, compared to us to ensure that they receive enough oxygen?
Differed chemical composition of haemoglobin
Where would the dissociation curves of llamas and (ew what) lugworms be moved and why?
To the left as they have haemoglobin with a higher affinity for oxygen than us
What does the fact that llamas have haemoglobin with a higher affinity for oxygen mean for them?
Haemoglobin becomes fully saturated at lower partial pressures of oxygen, and oxygen is only released at very low partial pressures of oxygen
In which condition would llamas face problems and why?
If moved down to sea level as the higher affinity of their haemoglobin for oxygen means that oxygen is only released at very low partial pressures of oxygen
Describe the haemoglobin of mice
Have a lower affinity for oxygen than humans
Why does the haemoglobin of mice have a low affinity for oxygen?
Mice have a very high metabolic rate as they’re so small
Need to released oxygen at a relatively high partial pressure to provide enough O2 to respiring tissues, as it’s in high demand
Where would the dissociation curve of a mouse move and why?
To the right as they have haemoglobin with a low affinity for oxygen
Draw and label a diagram that represents the Bohr effect and chloride shift
(See notes)
Give a detailed explanation of the Bohr effect and chloride shift
Carbon dioxide produced by respiring tissues diffuses into the blood plasma
Some of the carbon dioxide diffuses into the red blood cells
Carbon anhydride catalyses the reaction between carbon dioxide and water to form carbonic acid
Carbonic acid dissociated to form H+ and HCO3- ions
The HCO3- ions diffuse out of the red blood cell into the plasma, here they combine with Na+ ions to form sodium hydrogencarbonate - causes an electrochemical in balance between the red blood cell and its surroundings
To balance the outward movement of negatively charged ions, chloride ions, Cl- diffuse into the red blood cell; the chloride shift, which maintains electrochemical neutrality
Meanwhile, in the red blood cell, oxyhaemoglobin releases oxygen and combines with H+ ions to form haemoglobinic acid - haemoglobin has a higher affinity for hydrogen ions
Oxygen diffuses out of the red blood cell into the plasma and is passed to the respiring tissues by diffusion
The chloride shift
To balance the outward movement f negatively charged ions, chloride ions (Cl-) diffuse into the red blood cell
What does the chloride shift do?
Maintains electrochemical neutrality
Why does the Bohr effect allow haemoglobin to release oxygen more readily?
More CO2 produces more H+ ions, which release more oxygen from oxyhaemoglobin
What’s another advantage of haemoglobin combining with H+ ions?
Has a buffering effect which maintains the pH of red blood cells cytoplasm
What are the 3 ways that carbon dioxide is transported?
In solution in the plasma (about 5%)
As the hydrogen carbonate ion, HCO3- (about 85%)
Bound to the haemoglobin as carbamino-haemoglobin (about 10%)
What does the sequence of events in the blood cell described explain? (3 things)
Why most CO2 is carries in the plasma as HCO3- ions
The Bohr effect (more CO2 = more H+ ions = mor oxygen released from oxyhaemoglobin)
How CO2 results in the delivery of oxygen to the respiring tissues (more respiration = more CO2 = more oxyhaemoglobin dissociates = more oxygen to respiring cells)
Why does the sequence of events in the red blood cells explain the Bohr effect?
More CO2 = more H+ ions = more oxygen is released from oxyhaemoglobin
How does the sequence of events in the red blood cell explain how CO2 results in the delivery of oxygen to respiring tissues?
More respiration = more CO2 = more oxyhemoglobin dissociates = more oxygen to respiring cells
Where does blood carry heat to and from?
From the core of the body towards the surface (the skin)
What ones blood flow in the skin change in response to?
Changes in temperature
What does blood do when the temperature is hot?
More blood flows close to the skin surface so tat more heat leaves the blood (vasodilation)
Vasodilation
When more blood flows close to the skin surface when its heat so that more heat leaves the blood
What does blood do when it’s cold?
Smooth muscle in the walls of the arterioles close to the surface of the skin contact so that less blood flows close to the skin surface = less heat is lost (vasodilation)
Vasodilation
Smooth muscle in the walls of arterioles close to the surface of skin contract so less blood flows close to the skin surface when it’s cold = less heat is lost
Which muscles and where contract when it’s cold so that blood flows further from the skin’s surface?
Smooth muscle in the walls of the arterioles
What does the body work hard to maintain?
The osmotic balance of the body fluids
Give an example of the body working to maintain the osmotic balance of the body fluids
Blood plasma must be isotonic to the fluids inside the red blood cells
What does it mean that the blood plasma must be isotonic to the fluid inside the red blood cells?
Water potential of the plasma must be kept at equilibrium with the water potential of the cytoplasm inside cells
What happens when the water potential of blood is higher than the contents of a red blood cell? What’s the term for this?
Hypotonic
Water moves in via osmosis
Swells until it bursts (Haemolysis)
Cell contents spill out, destroying the cell
What happens when the water potential of plasma is lower than the contents of a red blood cell? What’s the term for this?
Hypertonic
Water moves out via osmosis
Cell shrinks
Other name for tissue fluid
Interstitial fluid
What does tissue fluid form from?
The fluid that escapes from the capillaries
Where does tissue fluid fill?
The spaces between the cells of the tissues
What does blood contain all the materials that cells need for?
Metabolism
Where do the materials that blood contains that cells need for metabolism need to travel from and to?
The plasma and the red blood cells
Into
The tissues and cells
How do the materials that blood carries that cells use for metabolism pass from the plasma and the red blood cells into the tissues and into cells?
By diffusion through the tissue fluid surrounding the cells
Functions of tissue fluid
Bathe all cells
Help maintain a constant environment around cells (maintain osmotic balance)
Supply oxygen, glucose, hormones, ions, amino acids, fatty acids and salts to cells
Remove waste from cells
Sketch a graph to represent the changes in blood pressure in the blood vessels
Label on it…
Diastolic pressure
Systolic pressure
Mean blood pressure
Pulse pressure
(See notes)
Which blood vessels have the highest blood pressure and why?
Aorta and arteries as they’re closest to the heart
What do the aorta and arteries show on a pressure graph and what explains this?
Rhythmical rise and fall
Corresponds to the contraction and relaxation of the ventricles in the heart (ventricular systole pushing blood out)
What does the rhythmical rise and fall of pressure in the aorta and arteries correspond to?
The contraction and relaxation of the ventricles in the heart (ventricular systole pushing blood out)
What happens in terms of pressure in the arterioles and why?
Friction with vessel walls causes a pressure drop
Have a large surface and are narrow
They’re also further away from the heart
Which blood vessels can adjust their diameter to control blood flow?
Arterioles
What does the pressure in the arterioles depend on?
Whether the arterioles are dilated (wide) or contracted (narrow)
When are the arterioles wide?
When dilated
When are the arterioles narrow?
When contracted
What happens in terms of pressure in the capillaries and why?
Further reduce pressure and therefore slows blood flow
Huge cross-sectional surface area
Also drops due to the leakage of substances into the tissues
Why is it important that pressure drops in the capillaries?
To slow down blood flow, to allow time for the exchange of substances
Describe the pressure in the veins - why is this?
Low pressure
Returning to the heart
How can pressure be increased in the veins?
By the massaging effect of muscles
What does the massaging effect of muscle increase the pressure of?
Veins
Describe the return flow of blood to the heart in the veins
Low pressure
Non-rhythmical
Where do capillaries take blood?
As close as possible to the cells
What happens due to the fact that capillaries take blood as close as possible to cells?
Rapid exchange of substances between blood and cells
The capillary bed
The network that capillaries form throughout every tissue (except cornea and cartilage)
What are the only tissues which the capillary bed doesn’t expand to?
Cornea and cartilage
Why are capillaries thin walled?
Single layer of endothelium
What do the tiny gaps between individual cells in capillaries allow and what are they called?
Fenestrations
Allow some components of blood to leak out into the surrounding tissue (this is tissue fluid)
The tissue fluid bathes the cells around the capillary
How does tissue fluid exit the capillaries? What are these?
Through fenestrtions
Tiny gaps between individual cells
What are capillaries permeable to?
Water and dissolved substances like glucose
Draw a capillary showing the arterial end and the venous end
(See notes)
In which direction does blood flow in a capillary in terms of the different ends?
From the arterial end to the venous end
What’s the net flow of liquid at the arterial end of the capillary?
Out of the capillary into the tissues
What’s the net flow of fluid at the venous end of the capillary?
From the tissues back into the capillary
What are the 2 types of pressures acting upon a capillary and in which direction is this?
Osmotic pressure (inwards)
Hydrostatic pressure (outwards)
Where does the atrial end of the capillary bed come from?
The arteries
Which pressure is highest at the atrial end of the capillaries?
Hydrostatic pressure ish other than osmotic pressure
What happens due to the hydrostatic pressure being higher than the osmotic pressure at the atrial end of capillaries?
Water and small soluble molecules are forced through the capillary walls, which form tissue fluid between the cells
What is forced from the capillaries at the atrial end of the capillary bed and what does this form?
Water and small soluble molecules (glucose, amino acids…)
Forms tissue fluid between the cells
What is NOT forced out of the capillaries at the atrial end and why?
Proteins and cells in the plasma
They’re too large
Where does the venous end of the capillary bed lead to?
The veins
Why does blood pressure fall along the capillary towards the venous end?
friction/resistance of the walls
Reduced volume of blood (fluid has escaped)
What happens to the blood pressure as blood moves along the capillary?
Falls
Which pressure is highest at the venous end of the capillary?
Osmotic pressure of the blood is higher than the hydrostatic pressure
What happens at the venous end of the capillary bed?
Most of the water from tissue fluid moves back into blood capillaries down its water potential gradient
Draw and label a graph to represent hydrostatic pressure and osmotic potential against the distance along the capillary
(See notes)
What is produced by tissue cells when they respire and what can be done with this?
CO2
Can be returned to the blood and be carried away as waste
Is all of the tissue reabsorbed back into the capillary at the venous end of the capillary?
No
At which end of the capillary isn’t all of the tissue fluid absorbed back into it?
The venous end
Why are lymph vessels necessary?
To avoid a build up of fluid in the tissue due to not all the tissue fluid being reabsorbed back into the capillary at the venous end
What does the body have to avoid a build up of fluid in the tissue?
The remainder of tissue fluid that wasn’t reabsorbed back into the capillary at the venous end is returned to the blood via lymph vessels
Draw and label the lymphatic system
(See notes ffion will bully me for this)
Where does the lymphatic system run?
Throughout the body
What is lymph fluid similar to and in what way?
Tissue fluid
Contains the same solutes
What’s different between lymph fluid and tissue fluid?
Lymph fluid has…
Less oxygen and fewer nutrients as they’ve been absorbed by body cells
Lymph has a more fatty material that has been absorbed from the intestines
(Main difference) Lymph contains many lymphocytes produced in the lymph nodes
Why does lymph fluid have less oxygen and fewer nutrients compared to tissue fluid?
They’ve been absorbed by body cells
Where does lymph fluid obtain its fatty material?
Absorbed from the intestines
Where are the lymphocytes of lymph fluid produced?
In the lymph nodes
Lymph nodes
Swellings found along the lymphatic system
What do lymph nodes do?
Filter any bacteria and foreign material from the fluid
What do lymphocytes do?
Engulf and destroy the bacteria and foreign materials that have been filtered by the lymph nodes
How is the lymphatic system part of the immune system?
Contains Lymphocytes which engulf and destroy bacteria and foreign particles
What ARE lymphocytes?
White blood cells
How does the lymphatic system help to avoid a build up of fluid in the tissue?
Drains excess tissue fluid and carries it to the thoracic duct which empties back into the circulatory system
Where does the lymphatic system carry excess tissue fluid to? What happens here?
The thoracic duct, which empties back into the circulatory system with the blood
What do lymph vessels contain and why?
Valves
Ensure that fluid doesn’t flow back into the tissues
Do lymph vessels form a complete circulation? Why?
No - they have blind endings
Where are lymph vessels found?
In the tissues, side-by-side with the capillaries
Do lymph vessels have a pump, such as how the capillaries have the heart? Why?
No
It realised on the pressure of the tissue fluid
What do proteins do in the plasma?
Maintain a low water potential in the blood
What would happen in terms of tissue fluid for a person with a low amount of protein in their diet and why?
Lack of protein, which maintain a low water potential in the blood
Lower osmotic pressure as the water potential of the blood increases
Less water reabsorbed into the blood by osmosis as the hydrostatic ensure is greater than the osmotic pressure
Fluid will accumulate in the tissues of the person
What, in terms of diet, can cause tissue fluid to accumulate in the tissues and why?
Low levels of protein
Proteins in the plasma maintain a low water potential in the blood, so with a lack of protein in a diet there’s a lower osmotic pressure as the water potential of blood increases
This means that less water is reabsorbed into the blood by osmosis as the hydrostatic pressure is greater than osmotic pressure
Fluid accumulates in the tissues
Oedema
The build up of fluid in the abdomen due to a lack of protein in the blood
The build up of fluid in the abdomen due to a lack of protein in the blood
Oedema
Compare the site of…
Plasma
Tissue fluid
Lymph
Blood easels
Surrounding body cells
Lymph capillary vessel
Compare the associated cells of…
Plasma
Tissue fluid
Lymph
Erythrocytes, granulocytes, lymphocytes
Granulocytes, lymphocytes
Granulocytes, lymphocytes
Compare the respiratory gases of…
Plasma
Tissue fluid
Lymph
More oxygen, less carbon dioxide
Less oxygen, more carbon dioxide
Less oxygen, more carbon dioxide
Compare the nutrients of…
Plasma
Tissue fluid
Lymph
More
Fewer
Fewer
Compare the large protein molecules of…
Plasma
Tissue fluid
Lymph
Yes
None
None
Compare the water potential of…
Plasma
Tissue fluid
Lymph
Lower
Higher
Higher
Why do veins have a large diameter lumen?
Needs to be wider to reduce resistance to blood flow allowing blood to flow easily under low pressure
Ensures that blood doesn’t lose its speed when returning to the heart
How are high pressures maintained in the arteries?
Due to elastic recoil of artery walls
What does the body do at high altitudes and why?
Build new red blood cells
Partial pressure of oxygen is low
How many cusps do both the pulmonary and aortic valves have?
3
What happens in the lungs in terms of the chloride shift? why?
the opposite, as there’s low levels of CO2
Where do we obtain Cl- ions from for the chloride shift?
the salt in our diets
why is it important that CO2 reacts with water during the chloride shift?
to ensure that it doesn’t accumulate in order to maintain the concentration gradient
why is it important that CO2 reacts with water during the chloride shift?
to ensure that it doesn’t accumulate in order to maintain the concentration gradient
why is it important that electrochemical neutrality is maintained in a red blood cell?
would otherwise stick to the capillary walls and each other, interfering with blood flow
Tendons function in the heart
Prevent inversion of bicuspid valve during contraction of left ventricle
What Prevent inversion of bicuspid valve during contraction of left ventricle in the heart?
Tendons
Why is a sigmoid curve more efficient for a respiratory pigment?
Small change in partial pressure = large change in % saturation
= more efficient unloading or oxygen to respiring tissues
What does a high pressure lead to in blood vessels?
Increased flow rate = increased rate of diffusion
Why is single circulation an advantage to fish?
Allows high pressure to the gills
Disadvantage of double circulation
Grate pressure and complexity leads to a greater risk of problems
How does tissue fluid move back into the capillary at the venous end of a capillary?
Via osmosis due to the osmotic pressure of the blood being higher than the hydrostatic pressure and so most of the water from tissue fluid moves back into blood capillaries, down its water potential gradient
Why does the body build new blood cells at high altitudes?
Low oxygen partial pressures, so more red blood cells = more haemoglobin = more oxygen
Why is there a higher hydrostatic pressure at the arteriolar end of the capillary?
Due to pumping of the heart
What maintains the low water potential of fluid in the capillaries when moving towards the venous end?
The fact that proteins and cells in the plasma are too large to be forced out
What affect does decreasing the pH have on the affinity of haemoglobin for oxygen?
It decreases its affinity for oxygen
When lower, there’s more H+, which haemoglobin has a higher affinity for than oxygen
Why doesn’t pressure fall to zero in the aorta and arteries?
Semi lunar valves at the base of the aorta close
Pressure rises upon another heartbeat
Elastic recoil of artery walls maintains pressure
What are the 2 factors that contribute most to the decrease in blood pressure in the capillaries?
Huge cross sectional area
More numerous
Are there more capillaries or arteries? How do we know?
Capillaries
Pressure decreases massively here = larger total c.s area
Open circulation
Blood leaves blood vessels
Blood bathes all tissues
How are muscles able to push on the walls of veins to help in moving blood?
Veins have thin walls
What stages does that shown on an electrocardiogram correspond to?
The control of the heartbeat stages
(SAN, AVN, Bundle of His etc…)
At which end of the capillary is water reabsorbed back into the blood?
Venue end
Why do oxyhaemoglobin not initially release oxygen until the partial pressure of oxygen drops significantly?
The 4th molecule of oxygen is more difficult to bind to haemoglobin,so a large increase in oxygen partial pressure is needed to reach full saturation
In which direction do ventricles contract?
From the base upwards
Which line on an electrocardiogram represents the atria filling with blood?
Isoelectric
Where is the isoelectric line on an electrocardiogram and what does it represent?
Following the T wave, before the next P wave
Represents the atria filling with blood
What do fenestrations in the capillaries allow in addition to allowing tissue fluid to pass out of the capillaries?
Allow CO2 and waste to be absorbed back in
What’s an additional adaptation of the tunica media to help them push blood through the artieries?
Elastic recoil of the fibres
What happens to the pressure in the aorta and the arteries upon each heartbeat?
Rises
What are electrolytes in the blood responsible for?
Maintaining osmotic balance in plasma
Where is the SAN?
Upper part of right atrium
Where is the AVN?
Lower part of right atrium
Why is oxygen released more readily in muscles where lactic acid has built up?
The acid lowers the pH = releases H+ ions, which haemoglobin has a higher affinity for than oxygen
Why is the flat region on the oxygen dissociation curve advantageous?
At high altitudes, oxygen isn’t lost
Why doesn’t CO2 reach equilibrium during the Bohr effect and why is this advantageous?
It “disappears” into carbonic acid
Maintains the concentration gradient so that CO2 keeps diffusing into the red blood cell
