blood and circulation

Question 1

single cell organisms do not have

Answer 1

circulatory systems

Question 2

how do single celled organisms obtain oxygen?

Answer 2

diffusion through the surface membrane of the cell

Question 3

single celled organisms have a high…

Answer 3

surface area to volume ratio

Question 4

what is the main function of a circulatory system

Answer 4

to transport oxygen by blood being pumped to a gas exchange organ to load ,oxygen and then pumped to other parts of the body where it unloads oxygen

Question 5

what are the two main types of circulatory systems in animals?

Answer 5

single circulatory system- blood pumped from heart to gas exchange organ and then directly to the rest of the body

double circulatory system- the blood is pumped from the heart to the gas exchange organ, back to the heart then to the rest of the body

Question 6

what are the two parts to a double circulatory system

Answer 6

pulmonary circulation- deoxygenated blood leaves the heart through the pulmonary arteries and is circulates through the lungs where it becomes oxygenated. The oxygenated blood returns to the heart through the pulmonary veins

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

Question 7

whats the difference between arteries, veins and capillaries

Answer 7

arteries- carries blood away from the heart and towards other organs
veins- carry blood towards the heart and away from other organs
capillaries- carry blood through organs linking arteries and veins

Question 8

describe the process of blood moving through the heart (cardiac cycle) PART 1

Answer 8

1) blood enters atria, cant pass into ventricles yet as the valves are closed
2- the walls of the atria contract. this raises the pressure of the blood in the atria which force the bicuspid and tricuspid valves open. 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 cant return to the atria

Question 9

describe the process of blood moving through the heart (cardiac cycle) PART 2

Answer 9

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 to arteries. The pulmonary artery carries blood to the lungs. The aorta has 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. Cycle begins again as the artria starts to fill with blood
.

Question 10

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

Answer 10

the left ventricle is thicker than the right- this is because the left ventricle has to pump blood to all the body which requires more pressure whereas the right ventricle only has to pump blood to the lungs which is a lot closer.
valves ensure that blood can only flow in one direction through the heart
the walls of the atria are thin- can be stretched to receive blood
walls of heart made out of cardiac muscle, contract constantly without becoming fatigued.
the heart needs its own supply of blood via coronary arteries, blood is returned via coronary veins

Question 11

what is coronary heart disease?

Answer 11

the coronary arteries are very narrow,easily blocked up by fatty substances including cholestrol in their walls.This can cut of blood supply to the heart so it can no longer recieve oxygen.
This means its unable to contract resulting in a heart attack.

Question 12

what makes coronary heart disease more likely?

Answer 12

genetics
high blood pressure
diet
smoking
lack of excersize

Question 13

what do arteries do, how are they adapted

Answer 13

carry blood from heart to organs
elastic tissues- allows arteries to stretch and recoil maintaining high blood pressure
thick muscular wall helps control the flow of blood by widening or narrowing the vessels

Question 14

what are veins, how are they adapted

Answer 14

-carry blood from the organs back to the heart
-pressure of venous blood lower than arteries so they can be thinner
-contain less elastic tissue and muscle
-veins also have semilunar valves which prevent the backflow of blood

Question 15

what are capillaries, how are they adapted

Answer 15

• carry blood through organs, bringing the blood close to every cell in the organism.
• capillaries must be small enough to fit between cells and allow materials to pass through their walls easily.
• walls of capillaries are one cell thick providing oxygen short distance for diffusion

Question 16

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Question 17

what are red blood cells only function?

Answer 17

to transport oxygen

Question 18

what features enable red blood cells to carry oxygen

Answer 18

• red blood cells contain haemoglobin, a protein that combines with oxygen to form oxyhemoglobin when there is a high concentration of oxygen in surroundings.
• when the concentration of oxygen is low, oxyhaemoglobin turns back into haemoglobin and red blood cells unload its oxygen
• red blood cells dont contain a nucleus- more haemoglobin can be packed into each red blood cell so more oxygen can be transported.
• biconcave shape- allows efficient exchange of oxygen in and out the cell.
  each red blood cell has a high surface area to volume ratio- large area for diffusion

Question 19

what is the main role of white blood cells

Answer 19

protect the body against invasion by disease causing micro-organisms (pathogens) such as bacteria and viruses

Question 20

what are the two ways white blood cells protect the body from pathogens?

Answer 20

phagocytosis
production of antibodies

Question 21

what is phagocytosis and what are phagocytes?

Answer 21

phagocytosis is when 70 percent of white blood cells can ingest microorganisms shuch as bacteria
phagocytes are the cells that do this (phagocytosis)

Question 22

how does phagocytosis work?

Answer 22

the phagocytes change their shape and produce extensions of their cytoplasm called pseudopodia.
the pseudopodia surround and enclose the microorganism in the vacuole.
once inside, the phagocyte secretes enzymes into the vacuole to break the microorganism down.
phagocytes mean cell eating

Question 23

which cells make antibodies

Answer 23

lymphocytes

Question 24

what are anti-bodies

Answer 24

soluble proteins that pass into the plasma. the anti bodies recognize the chemical markers (antigens) on pathogens surfaces.
the anti bodies stick to the surface antigens and destroy the pathogen by :
- causing bacteria to stick tgt- more easily recognised by phagocyte
- acting as a lanel on pathogen - more easily recognised by phagocyte
- causing bacterial cells to burst open
- neutralizing poisinous (toxins) produced by pathogens

Question 25

what are memory cells and immunity?

Answer 25

some lymphocytes don't kill microorganisms right away instead, they develop memory cells which remain in the blood for years. If the same microorganism re-infects a person, the memory lymphocytes start to reproduce anti bodies so the pathogen can be dealt with quickly. This is known as immunity.

Question 26

what is artificial immunity?

Answer 26

a person can be given artificial immunity to a disease without having contracted it itself. This is done by vaccination.

Question 27

how do vaccines work?

Answer 27

a person gets injected with a agent that carries around the same antigens as a specific pathogen. Lymphocytes recognise the antigens and multiply exactly as if that microorganism has entered the bloodstream. They produce memory cells and make the person immune to the disease. If the perso comes in contact with a real pathogen, they will experience a secondary immune response- anti body production happen faster than if not vaccinated

Question 28

what are platelets?

Answer 28

platelets are not whole cells, but fragments of large cells made in bone marrow. . if skin in cut, exposure to the air stimulates the platelets and damaged tissue to produce a chemical. This chemical causes the soluble plasma protein (fibrinogen) to change into insoluble fibers of another protein (fibrin). The fibrin forms a network across the wound, in which red blood cells become trapped. This forms a clot- prevents further loss of blood and entry to pathogens The clot develops into a scab- protects damaged tissue as new skin grows