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Flashcards in Exchange and Transport - Animals Deck (75)
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1
Q

Why do unicellular organisms not need a specialised exchange surface?

A

Because they have a high surface area to volume ratio.

2
Q

Why do multicellular organisms need specialised exchange surfaces?

A

They have a low SA:V ratio.

They have a high metabolic rate.

3
Q

What are the 4 features of a good gas exchange surface?

A

Large surface area
Thin layer (short diffusion pathway)
Good ventilation
Good blood supply

4
Q

In the lungs, what is the structure and function of cartilage?

A

Cartilage is strong and flexible and it forms incomplete rings around the trachea to prevent it from collapsing

5
Q

In the lungs, where is smooth muscle found and what is its function?

A

Found in the walls of the bronchioles and trachea.

Can constrict to limit airflow into the lungs.

6
Q

In the lungs, where are elastic fibres found and what is their function?

A

Elastic fibres are found in each alveolus.

They allow the alveoli to stretch, they also squeeze air out of the alveoli in elastic recoil.

7
Q

In the lungs, where is ciliated epithelium found and what is its function?

A

Ciliated epithelium lines the trachea and bronchi.

Cilia beat in unison to move mucus away from the lungs.

8
Q

In the lungs, where are goblet cells found and what is their function?

A

Goblet cells are found between and below epithelial cells.

They secrete mucus onto the lining of the trachea which traps dust and microorganisms.

9
Q

Outline what occurs during inspiration.

A

Diaphragm and external intercostal muscles contract.
Ribs move up and out.
Volume of the thoracic cavity increases.
Pressure in the thorax decreases below atmospheric pressure.
Air flows into the lungs.

10
Q

Outline what occurs during expiration.

A

Internal intercostal muscles contract and elastic fibres produce the elastic recoil effect.
Volume of the thoracic cavity decreases.
Pressure in the thorax increases above atmospheric pressure.
Air flows out of the lungs.

11
Q

What is spirometry?

A

Measuring changes in lung volume over time.

12
Q

In spirometry, what is the vital capacity?

A

The change in lung volume when a maximum inhalation is followed by a maximum exhalation.

13
Q

In spirometry, what is the tidal volume?

A

The change in lung volume during normal ventilation.

14
Q

In spirometry, what is the residual volume?

A

The volume of the lungs after a maximum exhalation.

15
Q

What is total lung capacity minus residual volume?

A

Vital capacity.

16
Q

What is the structure of the gills of a fish?

A

Each gill is supported by a gill arch, found at the gill cavity and protected by the operculum.
Each gill is made up of gill filaments which are made up of gill lamella. (to maximise SA)

17
Q

Outline fish inspiration.

A

The fish opens its mouth, increasing volume and decreasing pressure in the buccal cavity, causing water to move in.

18
Q

Outline fish expiration.

A

The fish closes its mouth and raises its buccal floor, decreasing volume and increasing pressure, causing water to exit through the operculum via the gills.

19
Q

What is the meaning of countercurrent flow in fish ventilation?

A

Blood and water flow past one another in opposite directions.

20
Q

What is the benefit of countercurrent flow?

A

Ensures that there is always a steep concentration gradient of oxygen and carbon dioxide. between the blood in the gills and the water.

21
Q

What are spiracles on an insect?

A

Small openings along the thorax and abdomen of insects that control airflow in. They can close through contraction of the sphincter to limit water loss.

22
Q

What are the tracheae in an insect?

A

Tubes leading away from the spiracles carrying air into the body of the insect. They divide into smaller tracheoles that run to respiring cells, this is where gas exchange takes place.

23
Q

What are the function of air sacs in an insect?

A

To store oxygen.

24
Q

How do larger insects ventilate?

A

Mechanical ventilation, where muscular pumping changes the volume of the thorax and abdomen.

25
Q

What happens when the tracheal fluid in an insect is removed?

A

Surface area is increased, but at the expense of greater water loss.

26
Q

What organisms have open circulatory systems?

A

Insects and molluscs.

27
Q

What are the features of an open circulatory system?

A

The system does not carry respiritory gases, only nutrients and waste.
The system is low pressure and blood cannot be directed.

28
Q

What organisms have a single closed circulatory system?

A

Fish

29
Q

What organisms have a double closed circulatory system?

A

Mammals (humans)

30
Q

What are the features of a closed circulatory system?

A

Blood is under high pressure.

Blood flow can be modified for different areas by contraction of smooth muscles in the walls of arterioles.

31
Q

What are the features of arteries?

A

Carry oxygenated blood (except pulmonary artery).
Under high pressure.
Formed of: elastic fibres, smooth muscle, collagen, endothelium

32
Q

What are the features of arterioles?

A

They link arteries and capillaries.

They have sphincter muscles which perform vasoconstriction and vasodilation.

33
Q

What are the features of capillaries?

A
Microscopic.
Link arterioles and venules.
Force rbc's to travel single file.
One cell thick walls.
Site of exchange - large surface area.
Blood flow slows due to small diameter.
34
Q

What are the features of veins?

A

Carry deoxygenated blood(expect pulmonary/umbilical veins)
Low pressure = one-way valves
Formed of: thin elastic fibres, smooth muscle, collagen and endothelium
Veins run between muscles so that blood is squeezed to the heart, especially by ventilation movements.

35
Q

What do venules do?

A

Connect capillaries and veins.

36
Q

What are the 2 parts of blood?

A

Cellular and fluid medium(blood plasma)

37
Q

What constitutes the cellular component of blood?

A

Erythrocytes(red blood cells), Leucocytes(white blood cells) and thrombocytes(platelets)

38
Q

What piece of equipment is used to count blood cells?

A

A haemocytometer.

39
Q

What is hydrostatic pressure in the capillaries, and what does it cause?

A

Blood pressure.

It forces blood plasma (excluding plasma proteins) out of the capillary.

40
Q

What is oncotic pressure in the capillaries?

A

Osmotic pressure caused by the concentration of plasma proteins. (draws water back into the capillaries)

41
Q

What is tissue fluid and when is it formed or reabsorbed?

A

Blood plasma minus plasma proteins containing dissolved solutes (respiratory gases, nutrients and waste products).
Formed and reabsorbed due to relative pressure of hydrostatic and oncotic pressure.

42
Q

At which end of the capillary is hydrostatic pressure highest?

A

Arterial end.

43
Q

How does oncotic pressure change over the length of the capillary?

A

It doesn’t.

44
Q

What is lymph?

A

Tissue fluid that does not return to the capillaries.

45
Q

What happens to lymph?

A

Enters the lymphatic system via lymph capillaries and is returned to the blood at the subclavian veins. Lymph veins have valves as they are at low pressure.

46
Q

What is the name of the tough sac that surrounds the heart and what is its function?

A

The pericardium.
Prevents the heart from being overfilled with blood.
Contains the pericardial fluid.

47
Q

What is the name and function of the fluid surrounding the heart?

A

Pericardial fluid.

Reduces friction.

48
Q

What is the function of tendinous cords in the heart?

A

Connected to the valves to prevent them from inverting.

49
Q

What is the function of the valves in the heart?

A

To ensure unidirectional flow.

50
Q

What does the term “myogenic heart” mean?

A

Cardiac muscles contract without external nervous or hormonal stimulation. (the heat has its own “pacemaker”)

51
Q

What are the 3 stages of the cardiac cycle?

A

Atrial systole
Ventricular systole
Diastole

52
Q

What happens during the atrial systole stage of the cardiac cycle?

A

The atrial wall contracts, forcing blood into the ventricles.
The atrioventricular valves are open.

53
Q

What happens during the ventricular systole stage of the cardiac cycle?

A

Ventricular wall contracts, forcing blood into the major arteries.
The atrioventricular valves are closed, the semilunar valves are open.

54
Q

What happens during the diastole stage of the cardiac cycle?

A

Atrial and ventricular walls relax and the chambers fill with blood.
The atrioventricular valves are open.

55
Q

Draw and label one cardiac cycle on an ECG (electrocardiogram).

A

See bio book

56
Q

What is tachycardia?

A

Fast heartbeat

57
Q

What is bradycardia?

A

Slow heartbeat

58
Q

What is fibrillation/arrhythmia?

A

Abnormal rhythm

59
Q

What is ectopic heartbeat?

A

Additional heartbeats

60
Q

Where does the impulse for the cardiac cycle begin?

A

The sino-atrial node in the right atrium.

61
Q

How is myogenic rhythm controlled?

A

Via nervous impulses and hormones

62
Q

What does the SAN generate?

A

Excitation waves (waves of electrical impulses)

63
Q

Where is the wave of excitation temporarily stopped in the cardiac cycle?

A

The septum (non-conductive)

64
Q

What happens to the cardiac impulse after it is temporarily stopped at the septum?

A

It is picked up by the atrio-ventricular node which sends the impulse down the bundle of his which branches into smaller purkyne fibres.

65
Q

In which direction do ventricles contract during ventricular systole?

A

From the apex upwards.

66
Q

What are the three ways carbon dioxide is transported in the blood?

A

Dissolved in plasma
Carboaminohaemoglobin in haemoglobin
Hydrogencarbonate ions in plasma (85%)

67
Q

In erythrocytes, what enzyme catalyses the reaction between water and carbon dioxide and what is the product?

A
Carbonic anhydrase
Carbonic acid (H2CO3)
68
Q

What does carbonic acid dissociate to in the red blood cells?

A

Hydrogen ions (H+) and hydrogencarbonate ions. (HCO3-)

69
Q

What effect do hydrogen ions have on haemoglobin?

A

Form haemoglobinic acid, allowing oxygen to be released into respiring tissues.

70
Q

What is the chloride shift?

A

Cl- ions move into erythrocytes from the blood plasma to maintain charge as hydrogencarbonate ions (negative) diffuse out.

71
Q

What are the axis on the oxygen dissociation curve?

A
y = %saturation of haemoglobin with oxygen
x = partial pressure of oxygen
72
Q

What is the bohr shift and what is its effect?

A

Increasing carbon dioxide concentration shifts the oxygen dissociation curve down and to the right (decrease in haemoglobin affinity for oxygen due to hydrogen ions).
This allows oxygen to leave haemoglobin in active tissues where CO2 concentration is high.

73
Q

What is different about fetal haemoglobin and why?

A

Higher affinity for oxygen. (to the left on the oxygen dissociation curve)
Allows fetal haemoglobin to take oxygen from the mothers blood.

74
Q

What are the names of the atrioventricular valves?

A

BLTR
=> bicuspid on the left side
tricuspid on the right side

75
Q

What is cardiac output equal to?

A

Stroke volume multiplied by heart rate.