Mass Transport in animals and circulatory system

Question 1

describe the structure of haemoglobin.

Answer 1

a quaternary structure protein as it consists of four polypeptide chains
each polypeptide carries a haem group which carry an iron ion can that can carry one oxygen molecule

Question 2

what is partial pressure?

Answer 2

the concentration of gas in the cells

Question 3

how does a dissociation curve work?

Answer 3

-the further left the curve is the greater the affinity for oxygen, so oxygen loads more readily and unloads less easily
-the further right the curve is the lower the affinity for oxygen, so oxygen loads less readily and unloads more easily

Question 4

how does partial pressure of oxygen ensure that oxygen is transported from the lungs to the respiring tissues?

Answer 4

-the partial pressure influences the affinity of haemoglobin for oxygen
-at a high partial pressure (in the lungs) the haemoglobin has a high affinity for oxygen so oxygen readily associates to the haemoglobin to form oxyhaemoglobin meaning the percentage saturation is high
-at a low partial pressure (in the respiring tissues) the haemoglobin has a low affinity for oxygen so oxygen readily dissociates meaning the percentage saturation is low

Question 5

describe the role of haemoglobin

Answer 5

component of red blood cells.
the oxygen molecules bind to the haem groups and are transported around the body to respiring tissues

Question 6

how does the partial pressure of carbon dioxide affect oxygen and haemoglobin binding?

Answer 6

-the bohr effect states that as partial pressures of carbon dioxide increase the conditions become acidic causing the haemoglobin to alter in shape
-this means the affinity for oxygen therefore decreases so oxygen readily dissociates in given partial pressure
-this is known as the Bohr effect

Question 7

how does the saturation of haemoglobin affect oxygen and haemoglobin binding?

Answer 7

-the binding of oxygen has a cooperative nature
-it is difficult for the first oxygen to bind
-once the first oxygen binds it changes the haemoglobins shape which uncovers haem group binding sites and makes it easier for the second and third molecules to bind which is known as positive cooperativity
-it is then slightly harder for the fourth oxygen to bind as there is a low chance of finding a binding site

Question 8

how does the haemoglobin of an organism adapt to its environment

Answer 8

-organisms in environments with low oxygen concentrations will have haemoglobin which has a higher affinity to oxygen
-organisms that are active and have a ow demand for oxygen will have haemoglobin with a lower affinity to oxygen

Question 9

how is foetal haemoglobin different to adult haemoglobin

Answer 9

-foetal haemoglobin has a higher affinity for oxygen
-this means maternal haemoglobin will dissociated itself in the placenta so the foetal haemoglobin can load with oxygen
-this ensures the foetus receives a sufficient supply of oxygen

Question 10

what are three common features of a mammalian circulatory system.

Answer 10

-suitable medium for transport, in mammals this is the blood which is water based so to allow many substances to dissolve in it
-means of moving the medium and maintaining pressure, in mammals the heart pumps the blood
-means of controlling the flow, in mammals they use valves

Question 11

how are atria adapted to their function?

Answer 11

thin-walled and elastic which allows them to stretch when they are filled with blood

Question 12

how are ventricles adapted to their function

Answer 12

they have thick muscular walls that contract to pump the blood at a high pressure, the left ventricle has a thicker muscle as it pumps blood to the whole body

Question 13

how are arteries adapted to their function

Answer 13

-arteries carry blood away from the heart to the rest of the body under high pressure
-have a thick cell wall to handle high pressure without tearing
-contain elastic tissue layer which enables them to stretch when under high pressure and recoil as ventricle relaxes
-contain smooth muscle which enables them to control blood flow by contracting to move blood along
-they have a narrow lumen to increase and maintain high blood pressure

Question 14

how are veins adapted to their function

Answer 14

-transport blood back to the heart under low pressure
-wide lumen to maximise blood flow to the heart
-thin walls as the blood transported under low pressure
-valves prevent the back flow of blood

Question 15

what is the role of tendons in the heart?

Answer 15

prevent inversion of valves due to high pressure

Question 16

why are two pumps needed instead of the one?

Answer 16

-maintains a blood pressure around the body as when blood passes through narrow capillaries the blood pressure drops thus is transported back to the heart in order to increase the pressure

Question 17

what are the three stages of the cardiac cycle?

Answer 17

-cardiac diastole
-atrial systole
-ventricular systole

Question 18

what occurs in cardiac diastole?

Answer 18

-atria and ventricles are relaxed
-elastic recoil of the heart increases the volume and lowers the pressure inside the heart chambers so blood enters the atria
-this increases the pressure in the atria forcing the atrioventricular valves open
-blood flows into the ventricles
-pressure inside the heart is lower than outside so the semi lunar valves remain closed

Question 19

what occurs in atrial systole?

Answer 19

-the atria contract which decreases the volume and increases the pressure in the atria
-atrioventricular valves are forced open and blood is pushed into the ventricles
-muscles from the ventricles remain relaxed to allow them to fill up with blood

Question 20

what occurs in ventricular systole?

Answer 20

-after a short delay, the walls of the ventricles contract
-delays ensure the atria is empty before the ventricle contract
- this increases the blood pressure so its higher than in the atria
-this forces the atrioventricular valves to close to prevent the back flow of blood a
-the semi lunar valves are forced open and blood is pushed into the arteries

Question 21

explain the importance of a double circulatory system in mammals

Answer 21

blood passes through the blood twice for each complete circulation of the body
this prevent mixing of deoxygenated and oxygenated blood so blood pumped to the body is fully saturated with oxygen
it allows blood to pumped at higher pressure as the blood pressure drops when travelling through the narrow arteries so re enters the heart to increase the pressure. this means substances are removed and take to body cells more rapidly

Question 22

define tissue fluid

Answer 22

-fluid surrounding cells in tissues
-made from small molecules from blood plasma
-consists of oxygen, water and nutrients
-does not contain red blood cells or large proteins

Question 23

how is tissue fluid formed and how is returned to the circulatory system?

Answer 23

-at the arterial end of a capillary their is a high hydro static pressure created by the contraction of ventricles
-this forces fluid and soluble molecules out of the capillaries
-large plasma proteins and large molecules remain in the capillaries resulting in a low water potential inside the capillaries
-water re enters the capillaries by osmosis at the venous end travelling down its water potential gradient
-the lymphatic system collects any excess tissue fluid which returns to the blood

Question 24

high blood pressure leads to an accumulation of tissue fluid explain why

Answer 24

-high blood pressure equals high hydrostatic pressure
-this increases the outward pressure from the arterial end of the capillary
-more tissue fluid is formed

Question 25

why is tissue fluid useful for cells

Answer 25

-cells take in oxygen and nutrients from tissue fluid
-metabolic waste is released into the tissue fluid