3.1

Question 1

Define single circulatory system

Answer 1

Blood passes through the heart once per complete circuit, for example, in fish

Question 2

Define double circulatory system

Answer 2

Blood passes through the heart twice per complete circuit, for example, in mammals

Question 3

What factors are effected by a single circulation system?

Answer 3

Reduced blood pressure, which limits the rate of O2 and nutrients to cells

Question 4

What are the benefits of a double circulatory system for mammals?

Answer 4

Maintains high blood pressure, this allows more O2 to reach cells so they can respire faster to support the level of activity for mammals, and maintain a body temperature

Question 5

What is the pulmonary system?

Answer 5

The deoxygenated blood is tranferred from the heart to the lungs through the pulmonary artery. When the blood is oxygenated, it is pumped back to the heart through the pulmonary vein.

Question 6

What is the systemic system?

Answer 6

The oxygenated blood is pumped through arteries around the body and then the deoxygenated blood is pumped back towards the heart through veins

Question 7

Define an open circulatory system

Answer 7

Blood is not contained in vessels and instead circulates through the body’s cavity, so tissues and cells are bathed directly in blood (haemocoel)

Question 8

Why do open circulatory systems work in insects

Answer 8

The oxygen from the air is carried directly tissues through an arrangment of traches , diffusion is enough to suit there demands.

Question 9

Describe the route of blood around a fish

Answer 9

atrium, ventricle, gilles, body, atrium …

Question 10

Describe a veins features and give there reasons

Answer 10

wide lumen as it only needs to pump at low pressure
thin walls that are less elastic and muscular
valves (semilunar): prevent backflow (so keep it going in one direction
don’t pulsate due to the smooth flow of blood

Question 11

Describe a capillary’s features and give reasons

Answer 11

wall is one cell thick for short diffusion distances
the capillary is just the endothilium with a large surface area

Question 12

Describe the feature of an artery and give there reasons

Answer 12

narrow lumen to keep high pressure
highly elastic to expand and recoil
thick muscular walls to whitstand force
no valves as blood is at higher pressure
pulsate

Question 13

What do all blood vessels have in common?

Answer 13

Have an inner lining made of a single layer of cells called the endothelium

Question 14

Why is the endothelium particulary smooth?

Answer 14

To reduce friction with blood

Question 15

Describe the tunica interna/intima, media and externa in an artery

Answer 15

tunica interna/intima: endothilium made from squamous cells, very smooth to reduce friction
tunica media: contains smooth muscle, collagen and elastic fibres
tunica externa: elastic fibres and collagen

Question 16

Why does the arteriole walls contain smooth muscle

Answer 16

to contract to constrict flow and limit it allowing it to go elsewhere

Question 17

Describe the tunica interna/intima, media and externa in an vein

Answer 17

tunica interna/intima: endothilium made from squamous cells, very smooth to reduce friction
tunica media: very thin containing some smooth muscles and elastic fibres
tunica externa: mostly collagen fibres

Question 18

Why do veins have valves?

Answer 18

To prevent backflow of blood and keep it flowing in one direction

Question 19

Describe the lumen of a capillary and give a reason for this

Answer 19

Very narrow around the same diameter of a erythrocyte, this ensures they are squeezed as they pass along the capillarys helping them give up there oxygen

Question 20

Decribe plasma and it’s function in the blood

Answer 20

liquid part, makes up 55% of the blood, made up of 90% water and 10% substances and transports substances around the body (CO2 from cells to lungs, urea from liverto kidneys, hormones and enzymes)

Question 21

Describe leucocytes and their function in the blood

Answer 21

5000-7000 per ml of blood, your bodys defence system against pathogens, many types such as: neutrophils (phagocytosis) and lymphocytes (produce antibodies and antitoxins)

Question 22

Describe thrombocytes (platelets) and their functions in the blood

Answer 22

200,000 to 300,000 per ml of blood. allow for blood clotting by initiating a reaction that turns soluble blood protein fribinogen into insoluble protein fibrin to form a blood clot. prevent loss of blood and entry of microorganisms

Question 23

Describe erythrocytes and their functions in the blood

Answer 23

4 - 6 million per ml of blood, 45% of blood volume, transport oxygen from lungs to cells

Question 24

What is the role of tissue fluid?

Answer 24

It is the fluid that allows the exchange of substances between the blood and cells

Question 25

What is hydrostatic pressure (blood pressure) in capillaries and what does it do?

Answer 25

As capillaries are narrow a pressure builds up which forces tissue fluid out of the blood plasma aswell as small molecules leaving cells and large proteins behind.

Question 26

What does (high) osmotic pressure do?

Answer 26

Return fluid of the blood at the veniole as blood still contains proteins which tissue fluid lack

Question 27

What is oncotic pressure?

Answer 27

Form of osmotic pressure exerted by proteins which pulls fluid into the circulatory system.

Question 28

Where is the overall net flow of fluid and what are the percentages?

Answer 28

out of the circulatory system into the tissues 90% returns back to the capillaries, 10% drains into lympth vessels

Question 29

Where is lymph moved towards and why?

Answer 29

The thorax to be returned to the blood

Question 30

What is the difference between tissue fluid and lymph fluid?

Answer 30

Lymph fluid contains less Oxygen, more CO2, less nutrients and more white blood cells which are lymphocytes

Question 31

Where are lymphocytes produced?

Answer 31

Lymph nodes

Question 32

What are lymph nodes and what do they do?

Answer 32

Swellings found at intervals along the lymphatic system that filter bacteria which lymphocytes engulf through phagocytosis and destroy

Question 33

What route does blood take through the heart (major veins and arteries, chambers and valves) starting with the vena cava?

Answer 33

vena cava, right atrium, tricuspid valve, right ventricle, semilunar valve, pulmanory artery, lungs, pulmanory vein, left atrium, bicuspid valve, left ventricle, semi lunar valve, aorta, body

Question 34

How are cardiac muscles joined?

Answer 34

intercolated discs

Question 35

What are the 3 stages of the cardiac cycle?

Answer 35

atrial systole, ventricular systole and diastole

Question 36

What happens in atrial systole?

Answer 36

atria contract, ventricles are relaxed, blood goes from atria to ventricles, bicuspid and tricuspid valves are open, semi lunar valves are closed

Question 37

What happens in ventricular systole?

Answer 37

ventricles contract, atrials relax, blood goes from ventricles to the pulmonary artery and aorta, tricuspid and bicuspid valves are closed and semi-lunar valves are open

Question 38

What happens in diastole (filling time)?

Answer 38

everything is relaxed, blood goes from pulmonary vein and vena cava into atria, valves in the vena cava and pulmonary vein are open, bicuspid and tricuspid valves and partially open, semi-lunar valves are closed.

Question 39

Where is the first electrical wave released from?

Answer 39

The sino-atrial node (SAN)

Question 40

When the SAN releases an electrical wave where does it go and what is casued?

Answer 40

Across the atriums causing them to contract and goes to the AVN

Question 41

What stops the initial wave from the SAN from going to the ventricles?

Answer 41

Layer of non-conducting collagen tissue

Question 42

What relays the initial electrical wave to the bundle of His?

Answer 42

The atrioventricular node (AVN)

Question 43

Where does the bundle of His pass the wave of charge on to?

Answer 43

Purkyne tissue

Question 44

What happens before the AVN released a wave of electrical charge to the bundle of His and why?

Answer 44

a slight delay to make sure the atria is empty

Question 45

What happens when charge reaches the purkyne tissue?

Answer 45

The ventricles are contractes simultaneously from the bottom up

Question 46

What is the simplified electrical activity of a heartbeat

Answer 46

SAN sends an electrical wave, atria contract, AVN recieves this, after a slight delay the AVN releases a charged wave to the bundle of His the wave up muscular walls and the ventricle contracts

Question 47

Where is the SAN?

Answer 47

In the right atrium

Question 48

What happens during polarization in the heart?

Answer 48

Gain of charge

Question 49

What happens during depolarization in the heart?

Answer 49

Loss of charge

Question 50

On a ECG: what does the P peak show

Answer 50

Contraction of the atrium

Question 51

On an ECG: what does the QPR peak show?

Answer 51

The contraction of the ventricle and the main heartbeat

Question 52

On an ECG: what causes the T wave?

Answer 52

Relaxation of ventricles

Question 53

What is brachycardia?

Answer 53

A resting hearbeat that is to fast, over 100bpm

Question 54

What is tachycardia?

Answer 54

A heartbeat that is to slow, under 60 bpm

Question 55

What is an ectopic heartbeat and what is it shown by on an ECG and what causes it?

Answer 55

An extra heartbeat caused by the early ontraction of the atria or ventricles, shown by an early P wave

Question 56

What does elavation of P-T show on an ECG?

Answer 56

Heart attack

Question 56

What is atrial fibrillation and what is it shown by on an ECG?

Answer 56

Irregular and abnormal heart rate where the atria and ventricles lose their rhythum shown by a small and unclear P wave