Mass Transport In Animals Flashcards
(26 cards)
Draw the general circulatory system in a mammal
Name the blood vessel with the lowest pressure
Vena cava
Do mammals have double or single circulatory systems and what does this mean
Double. This means the blood passes through the heart twice on each complete circuit
Draw and label the structure of the human heart
Why do mammals have double circulatory systems
This maintains the pressure needed to pump oxygen round the large bodies
Why is it important that oxygenated and deoxygenated blood don’t mix
As if this happens, less oxygen will be delivered to cells of respiring tissues, so less oxygen is available for aerobic respiration and that tissue/organ doesn’t grow or develop properly- it may stop working and die (causing death).
What are the arteries that deliver blood to the cardiac muscle of the heart called
Coronary arteries
What causes a heart attack and what is another name for a heart attack
Another name is a myocardial infraction
This is caused by a lack of glucose and oxygen being delivered to cardiac muscle via the coronary arteries (often if they become blocked in some way)
Give one example of a muscle that is myogenic
The cardiac muscle.
Means it doesn’t require an external electric impulse to contract
Outline the cardiac cycle
Atrial Systole:
- The muscles in the atrium wall contract simultaneously, decreasing the volume of the atria.
- This increases the pressure in the atria above that of the ventricles, causing the atrioventricular valves to open.
- Blood flows into the ventricles.
Ventricular systole:
- The atria relax, and the ventricles contract from the base up, decreasing the volume. This increases the pressure in the ventricles above that of the atrium, forcing the atrioventricular valves to shut (lub), preventing backflow.
- The ventricles continue to contract, increasing the blood pressure above that of the arteries, causing the semilunar valves to open.
- Blood leaves the heart via the aorta and pulmonary artery
Diastole:
- The ventricles relax, decreasing the pressure in the ventricles and the semilunar valves shut (dub).
- The atrioventricular valves open and the whole heart fills with blood.
Explain how tissue fluid is formed and how it may be returned to the circulatory system
-At the arterial end of the capillary, the hydrostatic pressure (which is forcing water and other dissolved substances out of the capillary) is higher than the osmotic pressure (which is forcing the tissue fluid back into the capillary). This is due to contractions of the left Ventricle.
- This forces the water and dissolved substances out of the capillary, forming tissue fluid.
- The water and dissolved substances are transferred with the tissues.
- As the blood moves from the arterial end of the capillary to the venous end, the hydrostatic pressure decreases (due to the loss of water and friction against the smooth endothelium).
-The water potential also decreases, because plasma protiens are too large to leave the capillary.
- This causes tissue fluid to move back into the capillary by osmosis.
- Any tissue fluid not re-absorbed by the capillary is absorbed into the lymphatic system and returned to the circulation at the subclavian vein.
Explain the control of the cardiac cycle
- The sinoatrial node releases a wave of depolarisation, causing the atria to contract simultaneously. This forces blood out of the atria and into the ventricles, through the atrioventricular valves. This is known as atrial Systole.
- The non-conductive tissue prevents the wave of depolarisation from spreading directly to the ventricles.
- When the wave of depolarisation reaches the atrioventricular node, which delays the impulse. This allows the atria to fully empty and the ventricles to fill with blood before they contact, allowing for maximum efficiency.
- The atrioventricular node releases the wave of depolarisation down the bundle of his made from purkyne tissue, which branches off and spreads the depolarisation up the walls of the two ventricles via Purkinje fibres. This causes the ventricles to contract from the base up.
-This efficiently empties the Ventricles, ensuring maximum blood is pumped per contraction.
- Blood then is forced out the Ventricles through the aorta and pulmonary artery.
Give the formula to calculate cardiac output
What is cardiac output
The volume of blood expelled from the left ventricle per minute
What is stroke volume
The volume in cm³ of blood expelled from the left Ventricle in one heart beat
What is heart rate
The number of cardiac cycles (beats) per minute
Which side of the heart has thicker tissue
The left side
Explain how caffeine causes an increase in heart rate
Causes more impulses to be sent along the sympathetic branch to the SA node, increasing the heart rate
How is the pressure in the left Ventricle and right Ventricle different
The pressure is higher in the left Ventricle
