mass transport in animals Flashcards
(92 cards)
1
Q
What are the adaptations that exchange surfaces have to increase the rate of diffusion?
A
- Large surface area
- Thin to produce a short diffusion pathway
- Maintained concentration gradient
2
Q
How do you calculate the rate of diffusion
A
(surface area x difference in concentration) / length of diffusion pathway
3
Q
Describe how the fish gill anatomy creates a large surface area
A
- There are 4 layers of gills on both sides of the head made up of stacked gill filaments
- Gill filaments are covered in gill lamellae where diffusion occurs
- This creates a large surface area
4
Q
Describe the adaptations of fish to increase the rate of diffusion
A
- Large surface area to volume ratio created by many gill filaments covered by many gill lamellae
- Short diffusion distance due to a capillary network in every lamella and very thin gill lamellae
- Maintain concentration gradient due to the countercurrent flow mechanism
5
Q
Describe the countercurrent mechanism in fish
A
Water flows over the gills in the opposite direction to the blood flowing in the capillaries
6
Q
Describe how the countercurrent mechanism in fish is advantageous
A
- It ensures that equilibrium isn’t reached as the concentration of oxygen in the water is always higher than that in the blood
- Also ensures that a diffusion gradient is maintained across the entire length of the gill lamellae
7
Q
Describe the anatomy of terrestrial insects
A
- Have an exoskeleton made of hard fibrous material for protection and a lipid bilayer to prevent water loss
- Don’t have lungs, they have a tracheal system
8
Q
What are the adaptations of insects that prevent water loss?
A
- Small surface area to volume ratio where water evaporates from
- Waterproof exoskeleton
- Spiracles where gases enter and water can evaporate from, they can open and close to reduce water loss
9
Q
What are the components of the tracheal system?
A
- Spiracles
- Trachea
- Tracheoles
10
Q
Describe the spiracles in the tracheal system
A
- Round, valve-like openings on the length of the abdomen
- Oxygen and carbon dioxide can enter/leave via the spircales
- The trachea attaches to the spiracles
11
Q
Describe the trachea in the tracheal system
A
- Network of internal tubes
- They have rings within them to strengthen the tubes and keep them open
- They branch into tracheoles
12
Q
Describe the tracheoles in the tracheal system
A
- Small tubes deep inside the abdomen
- They extend throughout all tissues to deliver oxygen to respiring cells
13
Q
List the different methods of moving gases in the tracheal system in insects
A
- Diffusion
- Mass transport
- Osmosis
14
Q
Describe how insects use diffusion to move gases in the tracheal system
A
- Cells respire
- This uses up oxygen and produces carbon dioxide
- Creating a concentration gradient from the tracheoles to the atmosphere
15
Q
Describe how insects use mass transport to move gases in the tracheal system
A
Insect contracts and relaxes their abdominal muscles to move gasses on mass
16
Q
Describe how insects use osmosis to move gases in the tracheal system
A
- During flight, muscle cells respire anaerobically to produce lactate
- This lowers the water potential of the cell
- Water moves into the cell via osmosis which decreases the volume in the tracheoles so more air from the atmosphere is drawn in
17
Q
Describe the adaptations of insects that ensure efficient diffusion
A
- The large surface area due to a large number of fine tracheoles
- Short diffusion pathway because walls of the tracheoles are thin and there is a short distance between spiracles and tracheoles
- Steep diffusion gradient due to the use of oxygen and carbon dioxide
18
Q
Define breathing
A
Movement of air into and out of the lungs
19
Q
Define respiration
A
Chemical reaction to release energy as ATP
20
Q
Define gaseous exchange
A
Diffusion of oxygen from the air in the alveoli into the blood and of carbon dioxide from the blood into the air in the alveoli
21
Q
What does the contraction of external intercostal muscles lead to
A
External intercostal muscle → contraction → inspiration
22
Q
What does the contraction of internal intercostal muscles lead to
A
Internal intercostal muscle → contraction → expiration
23
Q
Describe the process of inspiration
A
- external intercostal muscles: contract to pull the ribs up and out
- internal intercostal muscles: relax
- diaphragm: contracts to move down and flattens
- thoracic cavity pressure: initially drops, as air moves in it rise above atmospheric pressure
- thoracic cavity volume: increases
- movement of air: air moves into the lungs, as the atmospheric pressure is higher than that of the thorax
24
Q
Describe the process of expiration
A
- external intercostal muscles: relax
- internal intercostal muscles: contract to pull the rib down and in
- diaphragm: relaxes to move up and down
- thoracic cavity pressure: initially high but decreases as air moves out
- thoracic cavity volume: decreases
- the movement of air: air moves out of the lungs as the pressure in the thorax is higher than that of the atmosphere
25
What type of process is inspiration
An active process that requires energy from ATP
26
What type of process is expiration
Passive, doesn’t require energy
27
Compare inspiration and expiration
- **External intercostal muscles** contract in inspiration, relax in expiration
- **Internal intercostal muscles** relax in inspiration, contract in expiration
- **Diaphragm** contracts in inspiration, relax in expiration
- **Air pressure** in the lungs decreases in inspiration, increases in expiration
- **Lung volume** increases in inspiration, decreases in expiration
- In inspiration air moves into the lungs from a high to low pressure, in expiration it moves out of lungs from a high to low pressure
28
Describe the alveoli
They are air sacs made of a single layer of thin flat cells
29
Describe the adaptations of the alveoli for efficient diffusion
1. There are a lot of alveoli in the lungs which gives a large surface area for exchanging oxygen and carbon dioxide
2. The alveoli epithelium cells are thin to minimize diffusion distance
3. Alveolus is surrounded by a network of capillaries to exchange gasses, maintaining a concentration gradient
30
Describe the movement of air in the alveoli
1. Oxygen from the air moves down the trachea, bronchi, bronchioles and into the alveoli down a pressure gradient
2. The oxygen diffuses across the alveolar epithelium and then the capillary endothelium down a diffusion gradient
31
Why do we need a circulatory system?
Needed because multicellular organisms have a low surface area to volume ratio, so the circulatory system allows raw materials to be carried to body cells from specialised transport systems
32
What is the function of the heart
Heart pumps blood through blood vessels to reach parts of the body
33
What is the function of the blood
The blood transport respiratory gases, products of digestion, metabolic waste and hormones around the body
34
Where does the heart get its blood supply from?
Heart gets its supply from coronary arteries
35
What are the types of circulatory systems?
1. Pulmonary circulation
2. Systematic circulation
36
Describe pulmonary circulation
- Deoxygenated blood in the right side of the heart is pumped to the lungs
- Oxygenated blood returns to the left side of the heart
37
Describe systematic circulation
- Oxygenated blood in the left side of the heart is pumped to tissues
- Deoxygenated blood returns to the right side
38
Why is having closed double circulatory systems important?
- Prevents mixing of oxygenated and deoxygenated blood so blood pumped to the body is fully saturated with oxygen so there is efficient delivery of oxygen and glucose for respiration
- Blood can be pumped at a higher pressure and substances can be removed from the body more efficiently
39
Describe the coronary arteries
They deliver oxygenated blood to heart muscle/tissue
40
Describe the blood vessels which enter and leave the heart
1. Aorta - takes oxygenated blood from the heart to the respiring tissue
2. Vena cava - takes deoxygenated blood from respiring tissue to the heart
41
Describe the blood vessels which enter and leave the lungs
1. Pulmonary artery - takes deoxygenated blood from the heart to the lungs
2. Pulmonary vein - takes oxygenated blood from the lungs to the heart
42
Describe the blood vessels which enter and leave the kidneys
1. Renal arteries - take deoxygenated blood to the kidneys
2. Renal vein - take deoxygenated blood to the vena cava from the kidneys
43
Describe how the structure of the heart is related to its function
1. Atrioventricular valve - prevents backflow of blood from the ventricles to the atria
2. Semi-lunar valve - prevents backflow of blood from arteries to ventricles
3. The left side of the heart has a thick muscle wall to generate a high blood pressure for oxygenated blood as it has to travel a greater distance around the body
4. The right side has a thin muscular wall that generates a lower blood pressure for deoxygenated blood to travel a small distance to the lungs where high pressure would damage alveoli
44
Describe the structure of arteries and their function
- They carry blood **from the heart to the rest of the body** at a **high pressure**
- It has a **thick smooth muscle layer** that contracts and pushes blood along, it controls blood flow and pressure
- It has an **elastic tissue layer** that stretches as ventricles contract under high pressure, it recoils as ventricles relax when under low pressure. This evens out blood pressure and **maintains high blood pressure**
- A **thick wall** that withstands pressure and prevents bursting
- **Smooth endothelium** that reduces friction
- **Narrow lumen** that increases and maintains high blood pressure
45
What kind of blood do arteries carry
Oxygenated blood
46
Describe the structure of arterioles and their function
- They are divisions of arteries to smaller vessels which direct blood to different capillaries
- Thinner muscle layer than arteries, it contracts to reduce blood flow by narrowing the lumen, it relaxes to increase blood flow by enlarging the lumen
- Thinner elastic layer as blood pressure surges
47
Describe the structure of veins and their function
- They carry blood back to the heart under low pressure
- Wider lumen than arteries
- Very little elastic and muscular tissue
- Contain valves to stop the blood flowing backwards
48
How is blood flow maintained in the veins?
Contraction of skeletal muscle squeezes veins which maintain blood flow
49
What kind of blood do veins carry?
Deoxygenated blood except for pulmonary veins that carry oxygenated blood to the heart from the lungs
50
Describe the structure of the capillaries and their function
- They allow the efficient exchange of gases and nutrients between blood and tissue fluid
- Capillary wall is **one cell thick** and made of endothelial cells to create a **short diffusion pathway** for rapid diffusion
- Capillary bed is made of a **large network of branched capillaries** which are all thin to **increase the surface area** to volume ratio for rapid diffusion
- They have a **narrow lumen** that reduces the flow rate so there is **more time for diffusion** and exchange
- Capillaries **permeate tissues** to give a **short diffusion pathway**
- They have pores in walls between cells to allow substances to escape
51
How does blood flow in one direction
- The valves only open one way
- If there is high pressure behind a valve its forced open
- If the pressure is higher at the front of the valve its forces shut
- So blood flows in one direction
52
Define tissue fluid
The fluid surrounding cells and tissues
53
What is the function of tissue fluid
- Provides respiring cells with water, oxygen, glucose and amino acids
- It enables waste substances (urea, lactic acid, carbon dioxide) to move back into the blood
54
How is tissue fluid formed
1. Higher blood and hydrostatic pressure inside the capillaries due to the contraction of left ventricles than in the tissue fluid
2. This forces the water out of the capillaries into spaces surrounding the cells
3. Large plasma proteins remain in capillaries because they are too large to leave
55
How does tissue fluid return to the circulatory system
1. Hydrostatic pressure reduces as fluid leaves capillary
2. Due to water loss, an increasing concentration of plasma proteins that are too large to leave the capillaries lower the water potential in the capillary below the water potential of the tissue fluid
3. Water reenters the capillaries from the tissue fluid via osmosis down a water potential gradient
4. Excess water is taken up by the lymph system and is returned to the circulatory system
56
Describe what happens when there is an accumulation of tissue fluid due to protein
1. It’s caused by a low concentration of protein in the blood plasma
2. The water potential in the capillary is too high, so the water potential gradient is reduced
3. There is more tissue fluid at the arteriole end
4. Less/no water is absorbed into the blood capillary by osmosis
57
Describe what happens when there is an accumulation of tissue fluid due to high blood pressure
1. High blood pressure = high hydrostatic pressure
2. This increases outward pressure in arteriole end of the capillary and decreases inward pressure at the venule end of the capillary
3. So more tissue fluid is formed and less tissue is reabsorbed
4. The lymph system isn’t able to drain tissue fluid fast enough
58
Describe what occurs during diastole
1. The atria and ventricles relax
2. the pressure inside the atria increases
3. the volume inside the atria increases
4. the pressure inside the ventricles slowly increases
5. the volume inside the ventricles slowly increases
6. blood enters the atria via the vena cava and pulmonary vein
59
Describe what occurs during atrial systole
1. The atria contract decreasing volume and increasing pressure inside the atria
2. Atrioventricular valves open
3. Blood flows into the ventricles
60
Describe what occurs during ventricular systole
1. Ventricles contract decreasing volume and increasing pressure inside ventricles
2. Semi-lunar valves open
3. Atrioventricular valves shut
4. Blood is pushed out of the heart into arteries
61
Describe what heart valves do during atrial systole
1. The semi-lunar valves close
2. The atrioventricular valves open
3. So blood can move out of the atrium into the ventricle
62
Describe what heart valves do during ventricular systole
1. Semi-lunar valves open
2. Atrioventricular valves shut
3. So blood moves out of the heart
63
How do you calculate cardiac output?
Stroke volume x heart rate
64
What does cardiac output calculate?
The volume of blood pumped out of the heart per minute
65
How do you calculate heart rate?
Cardiac output / stroke volume
66
What does stroke volume measure?
The volume of blood pumped by the ventricles in each heartbeat
67
How do you calculate heart rate?
Cardiac output / stroke volume
68
What does heart rate measure
Number of heartbeats per minute
69
Describe the structure of haemoglobin
- It is a large protein with a quaternary structure made of **2 alpha helixes and 2 beta-pleated sheets**
- It has a **high affinity for oxygen**, each carries **4 molecules of oxygen**
- It has a **binocave shape** that increases the surface area for rapid oxygen diffusion
70
Describe ppO2 in the lungs
- lungs have a high ppO2
- haemoglobin has a high affinity for oxygen
- haemoglobin readily loads oxygen
71
Describe ppO2 in respiring tissue
- In respiring tissue, at low ppO2, haemoglobin has a low affinity for oxygen so oxygen readily unloads at the respiring tissue
- The high concentration of CO2 increases the rate of unloading
72
Describe what happens at the dissociation curve graph at high ppO2
- When ppO2 is high
- Haemoglobin has a high affinity for oxygen so it will readily associate with it
- So it has a high saturation of oxygen
73
Describe what happens on the dissociation curve graph at low ppO2
- When pO2 is low
- Haemoglobin has a low affinity for oxygen
- So it unloads oxygen rather than loading it
- So it has a low saturation of oxygen
74
Describe why the dissociation curve graph is S-shaped
- S-shaped because of the cooperative nature of oxygen binding
- Haemoglobin has a low affinity for oxygen as the first molecule associated with it
- The shape of haemoglobin changes so that it is easier for the next molecule to bind to it
- Now the haemoglobin has a high affinity for oxygen, so more oxygen molecules bind to it
- It becomes more saturated, and the shape of the haemoglobin changes so that it is harder for other oxygen molecules to associate with it
- That’s why at a high pO2 the rate of saturation decreases
75
Define the Bohr effect
Haemoglobin unloads oxygen more readily at a high pCO2
76
Describe the Bohr effect on pO2
- During exercise, cells respire and produce CO2 increasing the pCO2
- This increases the rate of oxygen unloading from haemoglobin, shifting the dissociation curve to the right
- The saturation of blood with oxygen is lower than the pCO2 so more oxygen is unloaded
77
What are the benefits of the Bohr effect?
Supplies respiring tissues with more oxygen for aerobic respiration
78
How does the association between O2 and haemoglobin weaken during the Bohr effect?
- Increased rate of respiration produces more CO2
- CO2 dissolves in blood plasma to give a weak acid
- Tertiary structure of haemoglobin changes slightly
- Association gets weaker
79
Describe what happens when the dissociation curve shifts to the left and how it is advantageous
- Curve shifts to the left = haemoglobin has a higher affinity for oxygen
- More oxygen associates with haemoglobin at a lower pO2 but dissociates less readily
- ADVANTAGE: good for organisms living in high altitudes or underground
80
Describe what happens when the dissociation curve shifts to the right and how it is advantageous
- Curve shifts to the right = haemoglobin has a lower affinity for oxygen
- Oxygen dissociates from haemoglobin more readily to respiring cells at a higher pO2 but associates less readily
- ADVANTAGE: good for organisms with a fast rate or respiration or fast metabolic rate
81
Define coronary heart disease
A type of cardiovascular disease, it occurs when the coronary arteries have lots of atheromas in them, which restricts blood flow to the heart muscle. It can lead to heart attacks.
82
Define atheromas
It is the narrowing of the artery wall due to cholesterol buildup behind the artery wall reducing blood flow to the heart
83
What blood vessel do atheromas occur in
Only arteries specifically coronary arteries
84
Describe how atheromas form
1. The wall of an artery is made of several layers, the endothelium is usually smooth and unbroken
2. If damage occurs to the endothelium, white blood cells (macrophages) and lipids from the blood clump together under the lining to form fatty streaks
3. Over time, more white blood cells, lipids and connective tissue build up and harden to form atheromas
85
What do atheromas lead to
Heart attacks, aneurysms, thrombosis
86
How do atheromas cause heart attacks?
- Atheroma causes the narrowing of the coronary arteries
- Restricting blood flow to the heart muscle supplying glucose and oxygen
- The heart will respire anaerobically, producing less ATP so the heart muscle won't have enough energy for muscle contraction
- Lactate (lactic acid) is produced, damaging the tissue and muscle
87
List the risk factors for cardiovascular disease
1. High blood cholesterol
2. Poor diet
3. Cigarette smoking
4. High blood pressure
5. Genetic factors
88
Describe high blood cholesterol as a risk factor for cardiovascular disease
- If blood cholesterol is high, then the risk of cardiovascular disease is increased because cholesterol is the main component of the lipid that makes an atheroma
- Atheromas can lead to high blood pressure and blood clots
- These could block the flow of blood to the coronary arteries which can cause a heart attack
89
Describe a bad diet as a risk factor for cardiovascular disease
- A diet high in saturated fat is associated with high cholesterol levels
- A diet high in salt increases the risk of CVD because it increases high blood pressure
90
Describe cigarette smoking as a risk factor for cardiovascular disease
- Nicotine and carbon monoxide increase the risk of CVD
- Nicotine increases the blood pressure
- Carbon monoxide combines with haemoglobin and reduces the amount of oxygen transported in the blood
- So reduces the amount of O2 available to tissues
- If the heart muscle doesn't get enough oxygen it can lead to a heart attack
- Smoking decreases the number of antioxidants in the blood that protect cells from damage, fewer of these means that cell damage in the coronary arteries is likely so atheromas will form
91
Describe high blood pressure as a risk factor for cardiovascular disease
- High blood pressure increases the risk of damage to artery walls
- Damaged walls have a higher chance of antheroma formation which can cause blood clots
- These can prevent the flow of blood to the heart muscle possible causing a heart attack
92
What are some predispositions factors of cardiovascular disease
- Genetic predispositions (inheritance of disease)
- Having high blood pressure as a result of another disease
