8 - Transport in Animals Flashcards
What is the name of the valve between the left ventricle and the aorta?
Aortic valve
What are 5 reasons that the circulatory system is important in animals?
- Metabolic demands of most multi-cellular animals high (so diffusion not enough) 2. Hormones/enzymes may be produced in 1 place but needed in another 3. Food digested in 1 organ system needs to be transported to individual cells all over body 4. Waste products need to be removed from cells and taken to excretory organs 5. SA:V ratio gets smaller as organism gets larger
Which type of circulatory system do humans have?
A closed one
Which type of circulatory system do insects have?
An open one
What happens to blood in a closed circulatory system?
Remains in vessels at all times
What are the 2 types of closed circulatory system?
Single or double (depending on how many times it passes through the heart per circuit of the body)
What happens to blood in an open circulatory system?
It is not contained within vessels at all times
What is the transport medium in insects called?
Haemolymph
What does haemolymph carry and what does it not carry?
Carries food and waste products, does not carry oxygen or carbon dioxide
What are some disadvantages of an open circulatory system?
Inefficient, cannot be controlled well
How is blood pumped around the body in insects?
Heart is a tube-like structure travelling along the length of the body, with a series of valves along it. It pumps blood to the head, after which it flows back towards the rest of the body and drains back into the heart
What is an example of an animal with a closed single circulatory system? (one where blood passes through heart once on each circuit of the body)
Fish
How is blood pumped around a fish’s body?
Deoxygenated blood from the body enters the heart’s one atrium, then moves into ventricle. It is then pumped to gills, becomes oxygenated, then completes circuit of body before returning to heart
Why is the single circulatory system inefficient?
Blood pressure drops sharply after it leaves gills, so hard to pump it round rest of body
How do fish counteract the problem of having low blood pressure once blood leaves the gills?
By having their heart placed near their gills
What is the function of arteries?
To carry blood away from the heart under high pressure
What is the function of veins?
To carry blood back to the heart under low pressure
What is the function of capillaries?
To take blood to individual tissues to allow gas and nutrient exchange
What are some adaptations of arteries?
Narrow lumen, thick, elastic wall, high pressure, smooth muscle on walls
What are some adaptations of veins?
Wide lumen, thin walls, valves to stop backflow of blood, little/no pressure
What are some adaptations of capillaries?
Very thin walls (up to 1 cell thick), very branched
Where does pulmonary circulation go to?
The lungs
Where does systemic circulation go?
The rest of the body
What are thin, branched arteries called?
Arterioles
What are venules?
Thin, branched veins
What order would blood flow through blood vessels in?
Artery—>Arteriole—>Capillaries—>Venules—>Veins
How is blood helped to keep flowing in veins?
The contraction of skeletal muscles and valves to prevent backflow
What percentage of blood is made up of plasma?
55%
What is the other 45% of blood made up of?
Erythrocytes, platelets and white blood cells
What is another name for white blood cells?
Leukocytes
What are 7 things transported in the blood? (try to name 4)
- CO2 and O2 to and from the cells and lungs 2. Nitrogenous waste from cells to excretory organs 3. Chemical messages/hormones 4. Digested food from the small intestine 5. Platelets to damaged areas 6. Cells and antibodies involved in immune response 7. Food molecules from storage to cells where they are needed
What are some functions of the blood other than as a transport medium?
Helps maintain steady body temperature, acts as a buffer to minimise pH changes
What is hydrostatic pressure?
The pressure that the fluid exerts on the walls of its container (I.e that of the blood on capillary walls)
What causes tissue fluid to form around capillaries?
High hydrostatic pressure in the capillary (helped by them being narrow) forcing fluid out
Why can’t large proteins or cells move out of capillaries?
Because the gaps in the capillary walls are too small
How is oncotic pressure created in the capillaries?
Water leaving the capillary via osmosis, whilst large proteins stay in the capillary
How is water pulled back into the capillary at the venous end?
Because oncotic pressure is greater than hydrostatic pressure
What amount of tissue fluid doesn’t return to the capillaries?
~10%
What happens to the 10% of tissue fluid doesn’t return to the capillaries?
It drains into the lymph capillaries, from which it joins into larger vessels
What do lymph nodes contain?
Lymphocytes, which help the immune system
Where does the lymph system drain lymph to?
Blood vessels near the heart
What is tissue fluid made of?
Blood plasma, except large plasma proteins such as albumin which cannot pass between cells in the capillary wall, as well as glucose, oxygen, water, amino acids, smaller proteins, waste molecules and carbon dioxide
When does tissue fluid become lymph?
When it enters the lymphatic system
What does the tissue fluid contain once it becomes lymph?
Little oxygen, glucose or proteins, but some CO2
How is lymph drained back to the heart?
A system of valves, as well as the contraction of nearby skeletal muscles
Where are red blood cells found?
Blood only as they are too large to pass through gaps in capillary walls
Where are white blood cells found?
Blood and lymph normally, with most in the lymph, although enter tissue fluid if there is an infection
Where are platelets found?
Only the blood normally, only found in tissue fluid if capillaries are damages
Where are proteins found?
All in the blood, only smaller ones in the tissue fluid, only antibodies in the lymph
Where are water and dissolved solutes found?
The blood, tissue fluid and lymph
What is the valve between the left atrium and ventricle called?
Bicuspid valve
What are the valves between the ventricles and the arteries called?
Semilunar valves
What are the valves between the atria and ventricles called?
Atrioventricular valves
What is the uppermost part of the Vena Cava called?
Superior Vena Cava
What is the lower part of the Vena Cava called?
Inferior Vena Cava
What open and close the atrioventricular valves?
Tendinous cords
What is the name of the valve between the right ventricle and pulmonary artery?
Pulmonary Valve
Which ventricle’s wall is more thickly muscled?
Left ventricle
What is the tissue seperating the left and right sides of the heart called?
Septum
What order does blood flow through the heart in?
Body—>Vena Cava—>Right Atrium—>Right Ventricle—>Pulmonary Artery—>Lungs—>Pulmonary Vein—>Left Atrium—>Left Ventricle—>Aorta—>Body
What are the arteries on the surface of the heart called?
Coronary arteries
What occurs during step 1 of the cardiac cycle?
- Ventricles are relaxed 2. Atria contract, decreasing their volume and increasing the pressure in them 3. This forces blood through the atrioventricular valves into the ventricles 4. Slight increase in ventricular pressure and chamber volume as ventricles receive blood from atria
What is cardiac contraction called?
Systole
What is cardiac relaxation called?
Diastole
What occurs during step 2 of the cardiac cycle?
- Atria relax 2. Ventricles contract (decreasing their volume and increasing the pressure in them) 3. Pressure higher in ventricles than in atria, forcing atrioventricular valves shut 4. Pressure in ventricles higher than in aorta and pulmonary artery, forcing open semilunar valves and forcing blood into the arteries
What occurs during step 3 of the cardiac cycle?
- Ventricles and atria both relax 2. Higher pressure in the aorta and pulmonary artery closes semilunar valves 3. Blood returns to heart, atria fill again due to higher pressure in vena cava and pulmonary vein. This starts to increase pressure of the atria 4. As ventricles continue to relax, their pressure falls below that of the atria and the atrioventricular valves open, allowing blood to flow in passively (without atrial contraction) 5. Atria contract, process repeats
In the heartbeat’s ‘wub-lub’ sound, what is the ‘wub’ sound?
The atrioventricular valves closing
In the heartbeat’s ‘wub-lub’ sound, what is the ‘lub’ sound?
The semilunar valves closing
What is systolic blood pressure?
Maximum blood pressure
When does systolic blood pressure occur in terms of the cardiac cycle?
After the blood leaves the heart in step 2
What is the name for minimum blood pressure?
Diastolic blood pressure
What does it mean that the heart is myogenic?
It can generate its own rhythm without nerve impulses
What is the full name of the SAN?
Sino-atrial node
What is the full name of the AVN?
Atrioventricular node
Where are the SAN and AVN found?
The wall of the right atrium
What is the purpose of the SAN?
It acts as the heart’s ‘pacemaker’, sending out the first regular electrical signal which causes the atria to contract
Why can’t signals from the SAN pass directly to the ventricles?
Because they are separated by a band of non-conducting collagen tissue, so they must go to the AVN instead
What is the purpose of the AVN?
It sends out another electrical signal slightly after the SAN (to allow all blood to flow from the atria), which is passed to the Bundle of His
What is the Bundle of His?
A group of muscle fibres responsible for conducting waves of electrical activity to the Purkyne tissue
What is the Purkyne tissue?
Finer muscle found in the walls of the ventricles
What does the Purkyne tissue do?
Carries waves of electrical activity to the walls of the ventricles, causing them to contract from the bottom up
In what way do the ventricles contract?
From the bottom up
What does a normal ECG look like?
Beats evenly spaced, 60-100 bpm
What does an ECG of a person undergoing bradycardia look like?
Beats evenly spaced but abnormally slow (<60 bpm)
What does an ECG of a person undergoing tachycardia look like?
Beats evenly spaced but abnormally fast (>100 bpm)
What does an ectopic heartbeat look like on an ECG?
Altered rhythm, extra beat followed by longer than normal gap before the next beat
What is atrial fibrillation?
Abnormal, irregular rhythm from atria, ventricles losing normal rhythm
What are the 5 waves in a normal heartbeat?
P, Q, R, S, T
What is the P wave caused by?
The contraction (depolarization) of the atria
When does the heart muscle depolarise (lose charge), contraction or relaxation?
Contraction
What is the QRS complex caused by?
The contraction (depolarization) of the ventricles
What is the main peak of the heartbeat on an ECG called?
The QRS complex
What is the T wave caused by?
The relaxation (repolarization) of the ventricles
When does the heart muscle repolarise (regain charge), contraction or relaxation?
Relaxation
How is an ECG produced?
By reading the changes in charge of the heart muscle using electrodes placed on the chest
What are some features of erythrocytes?
No nucleus, flattened and biconcave shape, contain haemoglobin molecules
What is formed when oxygen molecules loosely bind to haemoglobin?
Oxyhaemoglobin
Do oxygen molecules bind to haemoglobin loosely or tightly?
Quite loosely
What type of reaction is the binding of oxygen to haemoglobin?
Reversible
How many oxygen molecules can bind to each molecule of haemoglobin?
4 (so 8 atoms)
What is positive cooperativity?
Haemoglobin changes shape when 1 oxygen molecule binds to it, making it easier for other oxygen molecules to bind to the remaining 3 haem groups
What occurs at high partial pressures of oxygen?
There is a high concentration of oxygen molecules, so oxygen is readily taken up by the haemoglobin molecules
What occurs at low partial pressures of oxygen?
There is a low concentration of oxygen molecules, so oxygen is released by the haemoglobin molecules
What is the partial pressure of oxygen in the alveoli?
~10-12kPa
What is the partial pressure of oxygen in tissues?
~2-4kPa
What is the Bohr Effect?
The fact that oxygen is released more readily by haemoglobin when there is a higher concentration of CO2 molecules
Why is the Bohr effect helpful during exercise?
Actively respiring cells produce lots of CO2 and need lots of oxygen, so this naturally causes more oxygen to be supplied to them
What is the affinity for oxygen of fetal haemoglobin?
It has a higher affinity for oxygen than adult haemoglobin, allowing it to take up enough oxygen from the mother’s partially deoxygenated blood
How much carbon dioxide is carried in the plasma?
Around 5%
How is 10-20% of carbon dioxide transported in the blood?
It is combined with amine groups in the polypeptide chains of haemoglobin to form carbaminohaemoglobin
How much carbon dioxide is converted to hydrogen carbonate (HCO3-) ions and transported in the erythrocytes’ cystoplasm?
75-85%
What is the equation for the conversion of carbon dioxide to hydrogen carbonate ions?
CO2 + H2O ⇌ H2CO3 ⇌ H⁺ + HCO3⁻
Which enzyme catalyses the conversion of CO2 and H20 into carbonic acid (H2CO3)?
Carbonic Anhydrase
How are the H+ ions created by converting carbonic acid molecules to hydrogen carbonate ions and H+ removed from the erythrocyte?
By buffers such as haemoglobin, which combines with the ions to form haemoglobinic acid
Why is the chloride shift necessary?
It prevents a pH change within the cell
What is the chloride shift?
Where HCO3⁻ ions are removed from the cell by exchanging them with more useful Cl⁻ ions
