Mass Transport in Animals Flashcards
Define Digestion
Large biological molecules are hydrolysed by enzymes into molecules that can be absorbed across cell membranes
What happens to polysaccharides in digestion?
Their glycosidic bonds are hydrolysed and they are broken into disaccharides by an enzyme
What happens to disaccharides in digestion?
Their glycosidic bonds are hydrolysed and they are broken into monosaccharides by an enzyme
How is starch digested?
It is hydrolysed into maltose by amylase
How is maltose digested?
It is hydrolysed into alpha glucose by maltase
How is alpha glucose assimilated?
It is absorbed by co-transport with Na+
Where is amylase secreted?
The salivary glands and the pancreas
Where is maltase secreted?
In the small intestine
How is sucrose digested?
It is broken into glucose and fructose by sucrase
How is lactose digested?
It is broken into galactose and glucose by lactase
How are large lipid droplets broken down?
Bile salts are added in the process of emulsification
How are small lipid droplets broken down?
Two ester bonds between fatty acid molecules and glycerol are broken and a monoglyceride and two fatty acids are present as micelles
What are micelles?
Tiny droplets of monoglyceride and fatty acids that release the monoglyceride close to the cell surface membrane so that they can pass across the cell surface membrane and into the epithelial cells of the small intestine (pass across because they are fat soluble)
What are peptidases?
Enzymes that break the peptide bonds within a protein
What are endopeptidases?
Enzymes that break the peptide bonds inside a polypeptide chain
What are exopeptidases?
Enzymes that break the peptide bonds at the end of a polypeptide chain
What are membrane bound dipeptidases?
Enzymes that are attached to a membrane (e.g. the ileum) that hydrolyse the peptide bond in a dipeptide
How are amino acids absorbed?
By co-transport with Na+
What is haemoglobin?
A protein with a quaternary structure
Where is haemoglobin found?
In red blood cells
What does haemoglobin do?
Transports oxygen (haemoglobin + oxygen <=> oxyhaemoglobin)
What happens to the % saturation of O2 in haemoglobin as it travels around respiring cells and the lungs?
- Oxygen loads onto haemoglobin at a high partial pressure of oxygen (at the lungs)- Haemoglobin becomes saturated with oxygen- Oxygen unloads at cells where partial pressure of oxygen is low
What effect does the BohR shift have on the oxyhaemoglobin dissociation curve?
It shifts it to the right
Why does the BohR shift happen?
- When an organism respires a lot there is more carbon dioxide in the blood- An increase in carbon dioxide causes an increase in blood acidity- An increase in blood acidity decreases the haemoglobins affinity of oxygen- Oxygen unloads more easily at respiring cells- Haemoglobin is less saturated with oxygen because it has released more oxygen at respiring cells
What happens to haemoglobin in a higher oxygen environment?
- Haemoglobin has a lower affinity for oxygen- Releases more oxygen at cells- Useful for animals with a high rate of respiration- E.g. small mammals have a higher SA:V so they lose more heat per gram maintaining an internal temperature
What happens to haemoglobin in a lower oxygen environment?
- Lower partial pressure for oxygen in the lungs - Haemoglobin has a higher affinity for oxygen- Able to load oxygen at a lower partial pressure of oxygen
Arteries…
Flow away from the heart, have a narrower lumen than a vein, carry blood at high pressure, contain elastic tissue and folded endothelium (can stretch and recoil to maintain a smooth pressure) and contain thick muscle so they can contract and change the flow of blood (vasodilation and vasoconstriction)
Veins…
Have a wide lumen, with a thin layer of smooth muscle (can’t contract and less friction) and one way valves to prevent the backflow of blood. Veins carry blood at low pressure
Capillaries…
Surround all cells and exchange oxygen and glucose, the endothelium is only 1 cell thin so they have a high surface area and a short diffusion pathway
Arterioles…
Contain sphincters that are rings of muscles that can contract/dilate to regulate blood flow
What is the P wave?
The P wave represents the depolarisation of the left and right atrium and also corresponds to atrial contraction
What is the QRS complex?
The QRS complex represents the electrical impulse as it spreads through the ventricles and indicates ventricular depolarisation
What is the T wave?
T wave follows the QRS complex and indicates ventricular repolarisation
What is the renal vein?
Takes blood from kidney to heart
What is the renal artery?
Takes blood from heart to kidney
What is atheroma?
A build up of fatty plaque in the arteries that can cause thrombosis and increase the risk of aneurysm and can cause a myocardial infraction if it affects the coronary arteries (heart cannot get oxygen or glucose so muscle cells cannot respire)
What is thrombosis?
A blood clot in the arteries
What is an aneurysm?
When stretchy endothelium balloons out through the muscle of an artery
What is a myocardial infraction?
A heart attack
How is tissue fluid formed?
- Hydrostatic pressure is higher in the blood than in the tissue fluid- Water and small molecules are forced out- Large molecules stay inside the capillary
How is tissue fluid returned?
- Water potential in blood becomes lower than water potential in tissue fluid because proteins remain in the blood- Water moves into capillary by osmosis - Hydrostatic pressure drops in capillary so water moves in down pressure gradient - Tissue fluid drains into the lymph
What happens to pressure along the capillary bed?
Drops as you move along the capillary bed because water moves out
What is the role of the pulmonary artery?
Carries deoxygenated blood from right ventricle to the lungs
What is the role of the vena cava?
Carries deoxygenated blood from body to the right atria
What is the role of the aorta?
Carries oxygenated blood from left ventricle to body
What is the role of the pulmonary vein?
Carries oxygenated blood from lungs to left atria
What is the role of the semilunar valves?
Open when pressure in ventricles is greater than in blood vessels
What is the role of the atrioventricular valves?
Open when pressure in atria is greater than ventricles
What is the role of the SAN?
Initiates heart beat
What is the role of the AVN?
Delays the impulse, allowing atria to contract before the ventricles
What is the role of the bundle of His?
Carries the impulse to the Purkyne fibres
What is the role of the non-conductive tissue?
Stops impulse from SAN reaching ventricles
What are the three stages of a heart beat?
- Atria contract- Pressure higher in atria than ventricles- AV valves open- SL valves close2. Ventricles contract- Pressure is highest in the ventricles- AV valves close- SL valves open3. Atria and ventricles relax- Pressure is higher in atria (filling)- AV valves open- SL valves close
How is heart rate controlled?
- SAN initiates heart beat- Sends an electrical impulse across atria - Causes atria to contract - Non-conductive tissue prevents nerve impulses reaching the ventricles - Impulse arrives at AVN- AVN delays the impulse to allow atria to contract and empty before the ventricles contract- AVN sends impulse down the impulse down the bundle of His to the Purkyne fibres- Causes ventricles to contract from the base up
How is the left ventricle different to the right ventricle?
- Highest blood pressure- Most cardiac muscle- Contracts with greatest force- Pumps blood to whole body
What happens to the atria during atrial systole?
They are contracted and at high pressure
What happens to the ventricles during atrial systole?
They are relaxed and at low pressure
What happens to the atrioventricular valves during atrial systole?
Open
What happens to the semilunar valves during atrial systole?
Closed
What happens to the atria during ventricular systole?
They are relaxed and at low pressure
What happens to the ventricles during ventricular systole?
They are contracted and at high pressure
What happens to the atrioventricular valves during ventricular systole?
Closed
What happens to the semilunar valves during ventricular systole?
Open
What happens to the atria during diastole?
They are relaxed and at low filling pressure
What happens to the ventricles during diastole?
They are relaxed and at low lower pressure
What happens to the atrioventricular valves during diastole?
Open
What happens to the semilunar valves during diastole?
Closed
