Transport in Animals Flashcards
composition of blood
Human blood is made up of cells, plasma and fragments of cells (platelets).
Plasma is 90% water and has 10% solutes and plasma proteins.
cellular components in the blood
erythrocyte (red blood cells), as well as leucocytes (white blood cells)
properties of the erythrocytes
biconcave
thin cell surface membrane
no nucleus
contains carbonic anhydrase
no mitochondria
relatively small
how are red blood cells adapted for transport?
large surface area over which gases can diffuse (biconcave and thin membrane)
more space in the cytoplasm to contain 250 million haemoglobin molecules (no nucleus)
carbonic anhydrase enzyme to transport CO2
contains ATP by carrying out respiration so no oxygen is used up during transport to the tissues
types of leucocytes
granulocytes
agranulocytes
what is the difference between granulocytes and agranulocytes?
Granulocytes- have granular cytoplasm and the nucleus is lobed. They include eosinophils, neutrophils, and basophils.
Agranulocytes- do not contain any granules in the cytoplasm and can have a spherical/ bean shaped nucleus. They include the lymphocytes and monocytes with an irregular lobed nucleus.
shapes of the nucleus in different white blood cells
Neutrophils- irregularly lobed nucleus
Esinophils- bi-lobed nucleus
Basophils- s-shaped nucleus
Lymphocytes- large round nucleus
Monocytes- bean-shaped nucleus
types of lymphocytes
B cells
T cells
Which white blood cell produces antihistamine to counteract histamine?
esinophils
which white blood cell produces histamine and heparin?
basophils
what is the role of heparin?
heparin is an anticoagulant used to prevent the clotting of blood
reaction to show the role of haemoglobin in transporting oxygen
Hb + 4O2 → Hb(O2)4 (oxyhaemoglobin)
how is the haemoglobin molecule adapted to bind with oxygen faster?
the first oxygen molecule enters the red blood cells and binds with the haemoglobin, altering the shape of the molecule so that the 2nd oxygen molecule will bind more readily.
This causes a further change in shape of the haemoglobin so that the 3rd oxygen molecule will bind even faster and this is followed by the 4th oxygen molecule which binds the fastest.
in what conditions does haemoglobin combine readily with oxygen?
when oxygen concentrations are high because it has a high affinity for oxygen in those conditions
in what conditions would haemoglobin easily dissociate with oxygen?
it easily releases oxygen or dissociates when oxygen concentrations are low because it has a lower affinity for oxygen at lower oxygen concentrations.
what is undergone when haemoglobin binds with oxygen?
cooperative binding or allostery
what is the partial pressure of a gas?
The partial pressure of a gas refers to the pressure exerted by that gas in a mixture containing it.
units for partial pressure
mmHg or kPa
what is obtained when haemoglobin’s percentage saturation is plotted against partial pressure of oxygen?
an S-shaped oxygen dissociation curve is obtained
what does the S-shaped oxygen dissociation curve illustrate?
it shows the unloading, binding and dissociation of oxygen from haemoglobin
why is the oxygen dissociation curve not a straight line?
the affinity of haemoglobin for oxygen does not increase in a directly proportional manner with an increase in partial pressure of oxygen
why is the oxygen dissociation curve S shaped and not linear?
The affinity of haemoglobin for oxygen differs at low and high partial pressures of oxygen.
at lower partial pressures of oxygen, what is haemoglobin’s affinity for oxygen?
it has a lower affinity for oxygen, making it more likely to release oxygen
where are the conditions of low partial pressure of oxygen typically found?
in respiring tissues, where oxygen is being used up in respiration
at higher partial pressures of oxygen, what is haemoglobin’s affinity for oxygen?
it has a higher affinity for oxygen, making it more likely to bind and form haemoglobin
where are the conditions of high partial pressure of oxygen typically found?
in the lungs where inhalation brings air with a high oxygen concentration
what does the steep part of the curve at lower partial pressures of oxygen indicate?
A small drop in partial pressure causes a steep drop in haemoglobin’s saturation, leading to oxygen release to tissues.
what does the steep part of the curve at increasing partial pressures of oxygen indicate?
A small increase in partial pressure leads to a major increase in haemoglobin saturation.
how does the allosteric effect influence the oxygen dissociation curve?
binding the first oxygen molecule makes it easier for successive oxygen molecules to bind
what is the saturation level of haemoglobin in the lungs
95-97% as most haemoglobin is bound to 4 oxygen molecules
what is the saturation level of haemoglobin in actively respiring tissues?
20-25%, as haemoglobin releases about ¾ of its oxygen load.
why does haemoglobin release most of its oxygen in muscles?
because oxygen demand is high and the partial pressure of oxygen is low in actively respiring tissues
what is the Bohr effect?
The Bohr Effect indicates a decrease in the affinity of haemoglobin for oxygen at higher carbon dioxide concentrations or partial pressures. WIth the Bohr Effect, oxygen dissociation curves are shifted to the right as the carbon dioxide partial pressures increase.
why is the Bohr effect significant?
The Bohr effect is significant since it ensures that there is increased unloading of O2 in tissues that are very active and decreased likelihood that CO2 will combine with O2 in the muscles while exercising.
what happens to blood while exercising?
While exercising, the increased level of CO2 in the blood will cause the pH of the blood to decrease and this will also facilitate the unloading of O2 to the tissues from oxyhaemoglobin.
properties of the circulatory system
closed system because blood remains
double circulatory system since blood passes through the heart twice as it circulates
how does carbon dioxide enter red blood cells from tissues?
CO2 diffuses along a diffusion gradient from the tissues into the red blood cells.
what enzyme catalyzes the reaction between CO2 and H2O in the red blood cells?
carbonic anhydrase
what is formed when CO2 combines with H2O in the red blood cells?
carbonic acid
what happens to carbonic acid in red blood cells?
it dissociates into bicarbonate ions and hydrogen ions
How is the loss of HCO3- from red blood cells balanced?
Chloride ions (Cl-) diffuse into the red blood cells (chloride shift).
How is oxygen (O2) released to tissues in the presence of H+?
H+ displaces O2 from oxyhaemoglobin (HbO2), forming haemoglobinic acid (HHb).
relationship between CO2 and H+
The greater the CO2 concentration in tissues, the greater the H+ production, leading to increased O2 release from haemoglobin.
(Bohr Effect)
What happens to CO2 transport when blood reaches the lungs?
All reactions are reversed: CO2 is released from HCO3- and carbaminohaemoglobin, and O2 binds to haemoglobin.
How is bicarbonate (HCO3-) converted back to CO2 in the lungs?
HCO3- combines with H+ to form carbonic acid (H2CO3), which dissociates into CO2 and H2O.
What happens to Cl- ions in the lungs during CO2 transport?
Cl- ions diffuse out of the red blood cells into the plasma.
Why does haemoglobin have a higher affinity for O2 in the lungs?
The partial pressure of oxygen (PPO2) is higher in the lungs.
How much CO2 is dissolved directly in the blood for transport to the lungs?
5-7%
What percentage of CO2 combines with haemoglobin to form carbaminohaemoglobin?
Approximately 10%.
How is the majority of CO2 transported in the blood?
About 85% of CO2 is carried in the plasma as bicarbonate ions (HCO3-).
10% attached to haemoglobin (carbamino-haemoglobin)
5% dissolved in solution in the plasma
what is the difference between carbaminohaemoglobin and carboxyhaemoglobin?
Carbaminohaemoglobin is the carbon dioxide attached to haemoglobin.
Carboxyhaemoglobin is the carbon monoxide attached to the haemoglobin.
Properties of arterial walls
Thick walls composed of different types of tissu3s
Wall surrounds smaller lumen
Walls can withstand very high pressures without rupturing
Walls can maintain high pressure of blood as it moves through the heart
What is the structure of a venule?
Thinner wall, less smooth muscle and elastic tissue than an arteriole.
Function of a venule
C9nnects a capillary to a vein
Structure of a vein
Thinner wall than artery but with similar layers, the middle layer is more poorly developed, some have flaplike valves
Functions of a vein
Carries blood under relatively low pressure from a venule to the heart
serves as a blood reservoir
Valves prevent blood backflow.
Structure of a capillary
Single layer of squamous epithelium
Function of a capillary
Provides a membrane through which nutrients, gases and wastes are exchanged between blood and tissue fluid.
Structure of an arteriole
Thinner than an artery but with 3 layers, smaller arterioles have an endothelial lining, some smooth muscle tissue, and a small amount of connective tissue
Functions of an arteriole
Connects an artery to a capillary
helps control blood flow into a capillary by vasoconstriction or vasodilation.
Structure of an artery
Thick, strong wall with 3 layers- an endothelial lining, a middle layer of smooth muscle and elastic tissue, and an outer layer of connective tissue.
Function of the arteries
Carries blood under relatively high pressure from heart to arterioles.
What does the wall of the artery consist of?
a single layer of cells, which form an epithelium.
Where do the epithelial cells rest on in the capillary?
They rest on a basement membrane which consists of collagen fibres and glycoproteins
What allows soluble materials to pass 5hrough in the capillary
Small spaces between the epithelial cells
What occurs at the arterial end of the capillary?
At the arterial end, soluble materials such as salts, glucose, amino acids, along with small proteins, are forced through the epithelium and basement membrane into the tissue fluid around the tissues. This is called pressure filtration or ultrafiltration.
How is blood flow adapted to the structure of the capillary?
Because the diameter of the capillary is very small, the rate of movement of the blood along the capillary slows down and its pressure drops.
Large plasma proteins and red blood cells remain in the blood as it flows along.
How does exchange of substances occur in the capillary
Carbon dioxide and urea diffuse from the tissues into the blood and the large plasma proteins that have remained in the blood will lower the water potential of the blood. Osmosis of water back into the blood will take place at the venous end of the capillary, where the blood pressure is lower.
What are the chambers of the heart?
chambers, 2 thin-walled atria, and 2 thick-walled ventricles.
How’s the heart separated?
The left and right sides of the heart are separated by a septum so that the blood on the left side of the heart does not mix with the blood on the right side of the heart.
What is the size difference between the left and right ventricle?
The thickness of the left ventricular wall is 3x that of the right ventricular wall.
How does the heart work as a double pump?
the left side of the heart pumps blood to the body, and the right side of the heart pumps blood to the lungs, at the same time.
Where does the left atrium receive blood from?
The lungs
Where does the right atrium receive blood from?
The body
What blood vessels are present in the heart?
the pulmonary veins and aorta on the left side of the heart, and the vena cava and pulmonary artery on the right side of the heart.
Which valves are located on the right side of the heart?
the tricuspid valve and the semilunar valve
Which valves are located on the left side of the heart?
mitral/ bicuspid/ left atrioventricular valve as well as the semilunar valve
What is the directionof blood flow through the heart?
Oxygenated blood flows through the left side of the heart while deoxygenated blood flows through the right side.
Function of the heart as part of the double circulatory system?
the heart is able to efficiently send blood to both the body and the lungs at the same time so that deoxygenated blood reaches the lungs and oxygenated blood reaches the tissues.
Function of the heart regarding oxygenated and deoxygenated blood
To send oxygenated blood under pressure, to all parts of the body so that tissues can function normally.
To receive deoxygenated blood from the body and send it to the lungs so that carbon dioxide can be removed and oxygen taken up.
What does the greater thickness of the ventricular wall result in?
ensures that a sufficiently high pressure is generated on the left side of the heart to pump blood to all the parts of the body
What does the smaller thickness on the right ventricular wall help with?
ensuring that the pressure of the blood reaching the lungs will be low enough to avoid rupturing the delicate blood vessels around the lungs.
Function of the blood regarding heart rate
The ability of the heart rate to change by increasing or decreasing as needed. It ensures that the blood is able to meet the varying demands of the tissues in the body for food and oxygen.
what is the cardiac cycle?
a sequence of events in the heart during one heartbeat
what happens in atrial and ventricular diastole?
During atrial diastole and ventricular diastole, both the atria and ventricles are relaxed.
Blood enters the atria from the pulmonary vein and Vena Cava.
As these chambers fill, the pressure inside of the atria gradually rises and pushes against the atrioventricular valves, opening them.
As a result, about 70% of the blood that enters the heart flows directly into the relaxed ventricles.
The semilunar valves are closed at this time so there is no backflow of blood from the arteries into the heart.
what happens in atrial and ventricular diastole?
During atrial diastole and ventricular diastole, both the atria and ventricles are relaxed.
Blood enters the atria from the pulmonary vein and Vena Cava.
As these chambers fill, the pressure inside of the atria gradually rises and pushes against the atrioventricular valves, opening them.
As a result, about 70% of the blood that enters the heart flows directly into the relaxed ventricles.
The semilunar valves are closed at this time so there is no backflow of blood from the arteries into the heart.
what occurs during atrial systole?
During atrial systole, both atria contract at the same time, causing the pressure inside to rise.
This forces the remaining 30% of the blood into the relaxed ventricles
explain the process of ventricular systole
During ventricular systole, the atrial muscles are relaxed.
Both ventricles contract and this pushes blood against the AV valves, causing both of them to close.
Their closure causes the first heart sound, “lub”.
The AV valves begin to bulge back into the atria, causing a slight rise in the atrial blood pressure.
However, the papillary muscles contract and pull on the chordae tendinae, therefore preventing them from turning inside out.
At the same time, the contracting ventricle squeezes blood at high pressure against the semilunar valves, causing them to open.
Blood at high pressure therefore enters the arteries (aorta and pulmonary).
The AV valves remain closed during ventricular systole, and the pressure inside of the aorta gradually rises as blood fills them.
explain the last step of the cardiac cycle, ventricular and atrial systole
Both ventricles start to relax (ventricular diastole).
The blood pressure in the ventricles falls below that in the aorta and pulmonary artery.
Blood rushes back towards the semilunar valve which closes, making the second heart sound, “dub”.
The ventricles continue to relax and the pressure inside of them falls even further below the pressure in the atria.
Blood therefore flows from the atria into the ventricles as it pushes against the AV valves and causes them to open.
The ventricles fill to about 70% and the cycle is now complete.
when do atrioventricular valves close?
when the pressure in the ventricles exceeds the pressure in the atria
when do the atrioventricular valves open?
when the atrial pressure exceeds the pressure in the ventricles
when do semilunar valves close?
when the pressure in the aorta and pulmonary arteries exceeds that in the ventricles
when do the semilunar valves open?
when the pressure in the ventricles exceeds that in the pulmonary arteries and aorta
what does the human heart consist of?
cardiac muscles which are myogenic
what does myogenic mean?
the cardiac muscles naturally contract and relax on their own
how does the initiation of the cardiac cycle begin?
it begins in the pacemaker/ sinoatrial node (SAN), which consists of specialized, modified cardiac fibres, which are connected to nerve endings that form part of the autonomic nervous system
what is the rate of the electrical signal being spread i the SAN to both atria?
1m/s
why can’t the wave of excitation travel directly to the ventricles?
because there is a band of non-conducting tissue between the walls of the atria and ventricles
where does the wave of excitation from the pacemaker move to?
it reaches another group of cardiac muscles called the atrioventricular node (AVN)
where is the AV node located?
in the right atrium, close to the interventricular septum that divides the left and right sides of the heart
what happens to the AVN after a delay of 0.1s?
the AVN passes on the wave of excitation to the Bundle of His and Purkyne tissue, located in the dividing wall
how long after atrial systole does ventricular systole take place?
0.116-0.20s after
what happens with the wave of excitement in ventricular systole?
The wave of excitation continues to move downwards and outwards, as well as upwards into the ventricular walls from the apex of the heart.
how can the heart rate be modified or regulated?
by nerves that bring messages to the SAN or AVN from the brain and also by nerves that take information from the heart to the cardiac inhibitory and accelerator centres in the medulla of the brain
what are the cardiac centres in the medulla?
One is inhibitory- messages can travel from this centre to the SAN and AVN via the Vagus nerve and cause the heart rate to slow.
Messages can also travel from the accelerator centre (excitatory) via a sympathetic nerve to the SAN to increase the heart rate.
they both respond to information received from various stretch receptors, chemoreceptors and pressure receptors via nerves connecting the heart to the centres
how does carbon dioxide affect heart rate??
When the carbon dioxide concentration increases, the heart rate increases.
When blood passing through the hypothalamus has a high conc. of CO2, chemoreceptors there are stimulated and messages pass from those receptors along nerves to the cardiac accelerator centre.
From the centre, messages travel along a sympathetic nerve to the SAN/ pacemaker to increase the heart rate.
how does emotional stress affect the heart rate?
This can cause the heart rate to slow down (ex when receiving shocking news) and the person can faint away when insufficient blood reaches the brain.
Emotional stress can cause messages to travel from the cerebrum to the cardiac inhibitory centre. From there, inhibitory messages will travel via the vagus nerve to the SAN and AVN to slow down the heart rate.
owdoes anxiety affect heart rate?
This can cause the heart rate to increase.
Adrenaline is released from the adrenal glands, travels to the blood to the hypothalamus and then messages are sent to the cardiac accelerator centre.
From there, messages can travel via a sympathetic nerve to the SAN or pacemaker so increases the heart rate.
how does temperature affect heart rate?
An increase in blood temperature results in an increase in heart rate.
Blood temperature is monitored by the hypothalamus. If increased, impulses are sent from the cardiac accelerator centre, and from there to the AVN to increase the heart rate.
A decrease in blood temperature results in heart rate decreasing.
Hypothalamus detects this and sends messages to the cardiac inhibitory centre via nerves. From there, inhibitory messages travel via the vagus nerve to the SAN and AVN to slow down the heart rate.
how does potassium in the blood affect heart rate?
When stimulated by high potassium levels messages will travel to the cardiac inhibitory centre. Messages will travel by nerves to the cardiac inhibitory centre and from there, via the vagus nerve, to the SAN and AVN to lower the heart rate.
how do calcium levels affect heart rate?
High calcium levels detected by the chemoreceptors in the hypothalamus. Messages travel via nerves to the cardiac accelerator centre in the medulla, and from there, via the sympathetic nerve, to the SAN to increase the heart rate.
what is blood pressure?
Blood pressure refers to the force which blood exerts against the inner walls of blood vessels
what are the 2 components of blood pressure?
Systolic pressure- the max. Pressure in an artery during ventricular systole
Diastolic pressure- pressure in an artery during ventricular diastole
how does pulse develop?
when there is elastic stretch and recoil in the aorta and all arteries during the cardiac cycle, and this travels as a wave in all arteries
what are the factors affecting blood pressure?
cardiac output
peripheral vascular resistance
volume of circulating blood
viscousity of blood
elasticity of blood vessel walls
high sodium intake
anxiety
artherosclerosis
level of fitness
relationship between blood pressure and heart rate
blood pressure increase can bring about a decrease in heart rate
equation to obtain cardiac output
cardiac output = stroke volume x heart rate
what is stroke volume?
the volume of blood leaving the heart at each heartbeat
what is cardiac output?
the volume of blood flowing from the heart over a given time
