2H-transport humans

Question 1

why can simple, unicellular organisms rely on diffusion for the movement of substances in and out of the cell? why do they have to rely on diffusion?

Answer 1

single-celled organisms have no circulatory system so materials can easily move around without a special system. they also have no lungs, gills, etc.,, instead, they obtain oxygen via diffusion through the surface membrane of the cell. they have high surface area to volume ratio so their surface membrane is large enough to be able to supply all the oxygen that their volume demands.

Question 2

what can the supply to demand can be written as?

Answer 2

surface area/volume

Question 3

why do multicellular organisms need a transport system?

Answer 3

large animals (multicellular organisms) can’t get all the oxygen they need through their surface (even if their body would allow it) because there isn’t a high enough surface to supply all the volume. to overcome this they have special gas exchange organs and circulatory systems (same idea applies to circulatory system)

Question 4

what are the two main types of circulatory systems?

Answer 4

single and double

Question 5

what is a single circulatory system?

Answer 5

when the blood is pumped from the heart to the gas exchange organ and then directly to he rest of the body

Question 6

what is the double circulatory system?

Answer 6

the blood is pumped from the heart to the gas exchange organ, back tot he heart, and then to the rest of the body

Question 7

what are the 2 parts of the double circulatory system?

Answer 7

pulmonary circulation- deoxygenated blood leaves the heart through the pulmonary arteries and is circulated through the lungs, where it becomes deoxygenated. the oxygenated blood returns to the heart through the pulmonary veins
systemic circulation- oxygenated blood leaves the heart through the aorta and is circulated through all other parts of the body, where it unloads its oxygen. the deoxygenated blood returns to the vena cava.

Question 8

why is a double circulatory system more efficient than a single circulatory system?

Answer 8

this is because the blood it pumped twice, so the pressure is maintained and the blood is carried more quickly to organs

Question 9

what is the human circulatory system comprised of?

Answer 9

the heart, blood, blood vessels (carry blood around the body)

Question 10

what do the veins, arteries, capillaries do? what are the exceptions?

Answer 10

arteries - carry blood away from the heart towards other organs
veins- carry blood towards the heart and away from other organss
capillaries- carry blood through organs, linking the arteries and veins
APART FROM VENA CAVA VEIN AND PULMONARY VEIN

Question 11

wher eis the renal artery and vein?

Answer 11

goes to and away from kidneys

Question 12

where are the hepatic veins and arteries?

Answer 12

towards and away from liver

Question 13

what is the hepatic portal vein?

Answer 13

connects digestive system to liver??

Question 14

label the heart.

Answer 14

it must include:
aorta, vena cava, pulmonary artery, pulmonary vein, left atrium, bicuspid (mitral valve), left ventricle, right ventricle, right atrium, semi-lunar valves

Question 15

how is blood moved around the heart? explain it step by step. what are these series events called?

Answer 15

the cardiac cycle:
1. blood enters the atria. it cannot yet pass into the ventricles because the bicuspid (mitral) and tricuspid valves are closed
2. the walls of the atria contract. this raises the pressure of the blood in the atria which forces open the bicuspid and tricuspid valves. blood passes through these valves into the ventricles
3. when the ventricles are full, they contract. this increases the pressure of blood in the ventricles which closes the bicuspid and tricuspid valves again. blood cannot return to the atria
4. the ventricles continue to contract and the pressure continues to increase. this forces open the semi-lunar valves at the base of the aorta and the pulmonary artery. Blood is ejected into these two arteries. the pulmonary artery carries blood to the lungs. the aorta had branches that carry blood to all other parts of the body
5. as the ventricles empty, higher pressure in the aorta and pulmonary artery closes the valves in these blood vessels. the cycle then begins again as the atria starts to fill with blood

Question 16

how is blood moved around the heart? explain it step by step. what are these series events called?

Answer 16

the cardiac cycle:
1. blood enters the atria. it cannot yet pass into the ventricles because the bicuspid (mitral) and tricuspid valves are closed
2. the walls of the atria contract. this raises the pressure of the blood in the atria which forces open the bicuspid and tricuspid valves. blood passes through these valves into the ventricles
3. when the ventricles are full, they contract. this increases the pressure of blood in the ventricles which closes the bicuspid and tricuspid valves again. blood cannot return to the atria
4. the ventricles continue to contract and the pressure continues to increase. this forces open the semi-lunar valves at the base of the aorta and the pulmonary artery. Blood is ejected into these two arteries. the pulmonary artery carries blood to the lungs. the aorta had branches that carry blood to all other parts of the body
5. as the ventricles empty, higher pressure in the aorta and pulmonary artery closes the valves in these blood vessels. the cycle then begins again as the atria starts to fill with blood

Question 17

how is the heart adapted to its function?

Answer 17

• it is divided into a left and right side, with a wall of muscle called the septum dividing it. the wall of the left ventricle is much thicker than the right ventricle because it has to pump blood to all other parts of the body and requires more pressure
• the valves ensure the blood can only flow in one direction through the heart
• the walls of the atria are thin so that they can be stretched to receive blood as it returns to the heart but can contract with enough force to push blood through the bicuspid and tricuspid valves into the ventricles
  -the wall of the heart is made of cardiac muscle, which can contract and then relax continuously without becoming fatigued
• the cardiac muscle has its own blood supply - the coronary circulation so blood reaches the muscle via coronary arteries. it is then returned via the coronary vein through the right atrium

Question 18

how is the ventricle adapted to its function?

Answer 18

• it is divided into a left and right side, with a wall of muscle called the septum dividing it. the wall of the left ventricle is much thicker than the right ventricle because it has to pump blood to all other parts of the body and requires more pressure

Question 19

how are the valves adapted to its function?

Answer 19

• the valves ensure the blood can only flow in one direction through the heart

Question 20

how is the atria adapted to its function?

Answer 20

• the walls of the atria are thin so that they can be stretched to receive blood as it returns to the heart but can contract with enough force to push blood through the bicuspid and tricuspid valves into the ventricles

Question 21

how is the wall of the heart adapted to its function?

Answer 21

-the wall of the heart is made of cardiac muscle, which can contract and then relax continuously without becoming fatigued
- the cardiac muscle has its own blood supply - the coronary circulation so blood reaches the muscle via coronary arteries. it is then returned via the coronary vein through the right atrium

Question 22

do both atria/ventricles contract at the same time?

Answer 22

yes

Question 23

what is coronary heart disease?

Answer 23

a disease where the coronary arteries are blocked by a build-up of fatty substances (including cholesterol) in their walls. this can cut off the blood supply to the cardiac muscle and therefore it can no longer receive oxygen and glucose (so it can’t respire and release energy). this could result in a heart attack and lead to severe problems.

Question 24

what factors make coronary heart disease more likely?

Answer 24

• heredity - some people inherit a tendency to develop CHD
• high blood pressure - puts more strain on heart
• diet - eating large amounts of saturated fat is likely to raise cholesterol levels
• smoking - raises blood pressure and makes blood clots more likely to form
• stress - raises blood pressure
• lack of exercise - regular exercise helps reduce blood pressure and strengthens the heart

Question 25

why do our hearts beat faster when we exercise?

Answer 25

This is because the muscles must release more energy. they need an increased supply of oxygen for aerobic respiration so to deliver the oxygen, both the number of beats per min and volume of blood pumped (heart rate) with each beat (stroke volume) increase

Question 26

why does our heart rate increase when we are afraid or angry?

Answer 26

the increased output from the heart supplies extra blood to the muscles, enabling them to release extra energy through aerobic respiration. this allows us to fight or run away and is called the ‘fight or flight response’. this is triggered by the secretion of the hormone adrenaline from the adrenal glands. (this also make you stomach fluttery because the blood that would normally flow to your stomach and intestines has been diverted to the muscles)

Question 27

why does our heart rate decrease when we sleep?

Answer 27

less energy is needed to be released so we need less oxygen.

Question 28

what controls the change in our heart rate?

Answer 28

nerve impulses from the medulla

Question 29

how is the medulla involved in increasing heart rate when we exercise?

Answer 29

our muscles produce more CO2 because we respire more. receptors in the aorta and carotid artery (artery leading to the head) detect this increase. they send electrical signals called nerve impulses through the sensory nerve to the medulla. the medulla responds by sending nerve impulses along the accelerator nerve. When CO2 production returns to normal, the medulla receives fewer impulses so it responds by sending nerve impulses along a decelerator nerve.

Question 30

what does the accelerator/decelerator nerve do?

Answer 30

A- increases heart rate and blood pressure
D- decreases heart rate and force of contractions so BP goes back to normal

Question 31

what do the arteries do? what is it made of? how does this relate to their function?

Answer 31

carry blood from heart to organs. This arterial blood is pumped out of the blood at high pressures. the elastic tissues of the arteries allow them to stretch and recoil (spring back into shape) maintaining high blood pressure. the thick muscle walls, with muscle fibres and elastic tissue, help control the flow of blood by dilating and constricting the vessels
the arteries have a small lumen (central cavity) and an endothelium linning

Question 32

what do the veins do? what is it made of? how does this relate to their function?

Answer 32

carries blood from organs back to heart. the pressure of venous blood is much lower than in the arteries. it puts little pressure on the walls of the on the walls of the veins, so they are thinner (thin walls with little muscle and elastic tissue) and contain less elastic tissue and muscle.
- there is a large lumen (central cavity)
- endothelium lining
- veins have semilunar valves which prevent backflow

Question 33

what are the exceptions to veins and arteries and the direction in which blood flows?

Answer 33

pulmonary artery and vein (+umbilical artery/vein)

Question 34

what do the capillaries do? what is it made of? how does this relate to their function?

Answer 34

• carry blood through organs, bringing the blood close to every cell in the organ so that substances are transferred between blood and cells
• they are very small, they only just about fit red blood cells
• the capillary wall is one cell thick for short diffusion distance

Question 35

name the main components in blood.

Answer 35

plasma, red blood cells (erythrocytes), white blood cells (lymphocytes, phagocytes, platelets)

Question 36

what is plasma? what is its function?

Answer 36

• liquid part of blood: mainly water
• carries the blood cells around the body; carries dissolved nutrients, hormones, carbon dioxide and urea; also distributes heat around the body

Question 37

what is red blood cells? what is its function?

Answer 37

-biconcave, disc-like cells with no nucleus; millions in each mm^3 of blood
- transport of oxygen - contain mainly haemoglobin, which loads oxygen in the lungs and unloads it in other regions of the body

Question 38

what is lymphocytes? what is its function?

Answer 38

• about the same size as red cells with a large spherical nucleus
• produce antibodies to destroy microorganisms - some lymphocytes persist in our blood after infection and give us immunity to specific diseases

Question 39

what is phagocytes? what is its function?

Answer 39

• much larger than red cells, with a large spherical or lobed nucleus
• digest and destroy bacteria and other microorganisms that have infected our bodies

Question 40

where are red blood cells made? how long do they live? where are they destroyed?

Answer 40

bone marrow
They have a limited life span of about 100 days after which time they are destroyed in the spleen.

Question 41

what is haemoglobin? what does it do to oxygen?

Answer 41

an iron-containing protein.
haemoglobin associates (combines) with oxygen to form oxyhemoglobin when there is a high concentration of oxygen in the surroundings. We say that the red blood cell is loading oxygen. When the concentration of oxygen is low,
oxyhemoglobin turns back into haemoglobin and the red blood cell unloads
As red blood cells pass through the lungs, they load oxygen. As they pass through active tissues they unload oxygen in the lungs

Question 42

how are red blood cells adapted to their function?

Answer 42

• they don’t have a nucleus which means more hemoglobin can be packed into each red blood cell so more oxygen can be transported.
• they have a biconcave shape which allows for efficient exchange of oxygen in and out of the cell
• each red blood cell has a high SA:VOL ratio increasing the rate of diffusion
• the thin shape of the cell results in a short diffusion distance to the centre of the cell
• contains haemoglobin, an iron-containing protein which associates with oxygen to form oxyhaemoglobin

Question 43

what do phagocytes do?

Answer 43

1. phagocytes have a sensitive cell surface membrane that can detect chemicals produced by pathogen cells
2. they ingest microorganisms such as bacteria through phagocytosis.
3. they do this by changing their shape and producing extensions around their cytoplasm, called pseudopodia. The pseudopodia surround and enclose the microorganisms in a vacuole.
4. once this is done, the phagocyte excretes digestive enzymes into the vacuole to break the microorganism down

Question 44

what type of response are the phagocytes? what about lymphocytes?

Answer 44

P-non-specific, L-specific

Question 45

what are lymphocytes? what do they do?

Answer 45

• they make chemicals called antibodies. Antibodies are soluble proteins that pass into the plasma and they have a specific shape that is complementary to the antigens on the surface of the pathogen.
  1. pathogens such as bacteria and viruses have chemical ‘markers’ on their surfaces, which the antibodies recognise. these ‘markers’ are antigens
  2. the antibodies stick to the surface antigens and destroy the pathogen which can be done in a number of ways including: causing the bacteria to stick together, so the phagocytes can ingest them more easily, causing bacterial cells to burst open, neutralising poisons (toxins) produced by pathogens, acting as a ‘label’ on the pathogen so it is more easily recognisable to the phagocyte
  they can also make memory cells

Question 46

what is the function of plasma?

Answer 46

carries the blood cells around the body; carries dissolved nutrients, hormones, carbon dioxide and urea; also distributes heat around the body

Question 47

what is secondary immune response?

Answer 47

secondary immune response is much faster and more effective than the primary response. when lymphocytes develop memory cells which remain in the blood for many years (up to a lifetime). if the same microorganism re-infects a person, the memory lymphocytes start to reproduce and produce antibodies so that the pathogen can be quickly dealt with. This is immunity.
(no antibodies quickly rises, killing microorganism)

Question 48

what is vaccination? how is this done?

Answer 48

artificial immunity.
1. a person is injected with an ‘agent’ that carries the same antigens as a specific pathogen
2. lymphocytes recognise the antigens and multiply exactly as if that microorganism had entered the bloodstream
3. they produce memory cells and make the person immune to the disease
4. if the person comes into contact with the ‘real’ pathogen it will experience a secondary immune response. (antibody production happens sooner, faster, in greater quantity than if they had not been vaccinated and may be enough to prevent pathogen from reproducing and causing disease

Question 49

name some agent which are used in vaccines

Answer 49

• a weakened strain of the actual microorganism, e.g. vaccines against polio, tuberculosis (TB) and measles
• dead microorganisms, e.g. typhoid and whooping cough vaccines
• modified toxins of the bacteria, e.g. tetanus and diphtheria vaccines
• just the antigens themselves, e.g. influenza vaccine
• harmless bacteria, genetically engineered to carry the antigens of a different, disease-causing microorganism, e.g. the vaccine against hepatitis B.

Question 50

what is the response to infection? (from the pathogen entering the bloodstream and the influence of phagocytes and lymphocytes)

Answer 50

Response to infection
* The stages of infection and the subsequent immune response are as follows:
1. The pathogen enters the blood stream and multiplies
2. A release of toxins (in the case of bacteria) and infection of body cells causes symptoms in the patient
3. Phagocytes that encounter the pathogen recognise that it is an invading pathogen and engulf and digest (non-specific response)
4. Eventually, the pathogen encounters a lymphocyte which recognises its antigens
5. The lymphocyte starts to produce specific antibodies to combat that particular pathogen
6. The lymphocyte also clones itself to produce lots of lymphocytes (all producing the specific antibody required)
7. Antibodies destroy pathogens
8. Phagocytes engulf and digest the destroyed pathogens

Question 51

what does an organism have immunity?

Answer 51

• An organism has immunity when they have sufficient levels of antibodies to protect it from a particular disease
  
  • As a result, they do not suffer from the disease or its symptom

Question 52

what are platelets?

Answer 52

Platelets are not whole cells, but fragments of large cells made in the bone marrow.

Question 53

what do the platelets do if you have hurt yourself e.g., cut youself? what is its function?

Answer 53

1. If the skin is cut, exposure to the air stimulates the platelets and damaged tissue to produce a chemical.
2. This chemical causes the soluble plasma protein fibrinogen to change into insoluble fibres of another protein, fibrin.
3. The fibrin forms a network across the wound, in which red blood cells become trapped
4. This forms a clot, which prevents further loss of blood and entry of microorganisms that may be pathogens.
5. The clot develops into a scab, which protects the damaged tissue while new skin grows.