🔴2.3 Adaptations For Transport In Animals Flashcards
1
Q
What 3 things do transport systems in animals have to have?
A
- suitable medium in which to carry materials
- pump, such as the heart, for moving the blood
- valves to maintain the flow in one direction
2
Q
What other features do some transport systems in animals have?
A
- respiratory pigment in vertebrates and some invertebrates but not insects which increase the volume of oxygen that can be transported
- A system of vessels with a branching network to distribute the transport medium to all parts of the body
3
Q
Define an open circulatory system
A
A system where the blood does not move around the body in blood vessels but it bathes the tissues directly while held in a cavity called the haemocoel
4
Q
What is the haemocoel
A
A large space in the body cavity where the transport medium in an open system is moved to
5
Q
Name an example of a group of organisms that have open systems
A
Insects
6
Q
Describe the open circulatory system in an insect
A
- have a long dorsal tube shaped heart along entire length of the body
- pumps blood out at low pressure into the haemocoel
- haemocoel = where materials are exchanged between blood and body cells
- blood returns slowly to the heart and open circulation starts again
7
Q
Why do insects not require respiratory pigment?
A
Because oxygen diffuses directly to the tissues from the tracheae so the blood does not need to transport oxygen
8
Q
Define closed circulatory system
A
The blood in an organism moves in blood vessels.
9
Q
What are the 2 types of closed circulatory system?
A
- single circulation
- double circulation
10
Q
What happens in single circulation
A
The blood moves through the heart once in its passage around the body
11
Q
Describe the circulation in an earthworm
A
1-blood moves forward in he dorsal vessel and back in the ventral vessel
2-five pairs of ‘pseudo hearts’ (thickened muscular blood vessels) pump the blood from the dorsal to the ventral vessel and keep it moving.
12
Q
Describe the circulation in fish
A
1) ventricle of the heart pumps deoxygenated blood to the gills
2) pressure falls
3) oxygenated blood is carried to the tissues
4) deoxygenated blood returns to the atrium of the heart
5) blood moves to the ventricle and circulation starts again
13
Q
What happens in double circulation
A
The blood passes through the heart twice in its circuit around the body
14
Q
Name an example of an organism with a close circulation system
A
Mammals
15
Q
Are organs in direct contact with the blood
A
No, but they are bathed by tissue fluid which seeps out of the capillaries
16
Q
Describe briefly the pressure changes in the heart
A
1- blood pumped by muscular heart at High pressure
2- blood pressure is reduced in the lungs
3-blood returned to the heart raising pressure again to pump it to rest of the body
17
Q
Describe the circulation type in insects, earthworm, fish and mammals
A
Insect= open Earthworm= closed single Fish= closed single Mammal= closed double
18
Q
Is there respiratory pigment in insects, earthworms, fish and mammals
A
Insect = no Earthworm = yes Fish = yes Mammals = yes
19
Q
Describe the heart shape/type in insects, earthworms, fish and mammals
A
Insects = dorsal tube shaped Earthworm = ‘pseudohearts’ Fish = 1 atrium and 1 ventricle Mammals = 2 atrium and 2 ventricles
20
Q
LEARN SINGLE CIRCULATION DIARGAM ON PG 183
A
LEARN DOUBLE CIRCULATION DIAGRAM ON PG 183
21
Q
What does a great metabolic rate require
A
Requires more rapid delivery of oxygen and glucose and more rapid removal of waste such as CO2
22
Q
What are the two key features of a double circulation system
A
The pulmonary circulation
The systemic circulation
23
Q
Describe the pulmonary circulation in mammals
A
Pulmonary circulation serves the lungs
1) right side of the heart pumps deoxygenated blood to the lungs
2) Oxygenated blood returns from the lungs to the left side of the heart
24
Q
Describe the systemic circulation in mammals
A
Systemic circulation serves the body tissues
1) left side of the heart pumps oxygenated blood to the tissues.
2) deoxygenated blood from the body returns to the right side of the heart
25
Which is more efficient the double circulation of a mammal or single circulation of a fish and why?
The double circulation of a mammal because oxygenated blood can be pumped around the body at a higher pressure
26
What are the 3 types of blood vessels
Arteries
Veins
Capillaries
27
What is the endothelium (in arteries and veins)
Innermost layer
One cell thick
Surrounded by the tunica initma
28
What is the purpose of the tunics intima
Smooth lining reducing friction with a minimum resistance to blood flow
29
What is inside the artery and veins from the centre outwards
```
Lumen
Endothelium
Tunica initma
Tunica media
Tunica externa
```
30
- What is the middle layer of the artery/vein
| - what does it contain
The tunica media
| -contains elastic fibres and smooth muscle
31
Where is the tunica media thicker, the arteries or veins
| What does this allow?
Thicker in the arteries
32
What does the elastic fibres in the tunica media allow?
Allows stretching to accommodate changes in blood flow and pressure as blood is pumped from the heart
33
What happens when the elastic fibres in the tunica media recoil?
How can we tell when this occurs and what’s its purpose?
- At certain point stretched elastic fibres recoil pushing blood on through the artery
- this is felt as the pulse and maintains blood pressure
34
What regulates blood flow and also maintains blood flow?
The contraction of smooth muscle in the tunica media maintains blood flow and the blood pressure as the blood is transported further from the heart
35
What is the outer layer of veins/arteries called?
| What does it contain?
Tunica externa
| Contains collagen fibres which resist over-stretching
36
Name the average diameter of arteries, veins and capillaries
```
Artery = 10mm
Vein = 6mm
Capillary = 0.02 mm
```
37
Which has a larger lumen, the vein or artery?
| Why is this needed?
The vein has a larger lumen
-Needed as veins carry deoxygenated blood towards the heart at low pressure :: blood moves slower and often against gravity :: large lumen ensures it’s still transported efficiently
38
Describe the purpose of arteries
- carry blood away from the heart
- contain thick, muscular walls
- branch into smaller vessels called arterioles which further subdivide into capillaries
39
Why is it essential for artery walls to be thick and muscular
To withstand the bloods high pressure, derived from the heart
40
Describe the purpose of capillaries
-form a vast network that penetrates all tissues and organs of the body
41
How does blood return to the heart
Blood from capillaries collects into venules which takes blood into veins which return it to the heart
42
Why is the blood pressure and flow rate lower in veins than arteries
Because they have a lumen with a larger diameter and thinner walls with less muscle than arteries
43
How does blood return to heart for veins above the heart
By gravity
44
How does blood return to heart for veins below the heart
By pressure from surrounding muscles
45
What valves do veins have along their length?
What does this ensure?
Where are such valves not found?
- Semi lunar valves
- ensure one directional flow (prevent backflow)
- not found in arteries except the aorta and pulmonary artery
46
What can the faulty functioning of valves cause? (Disease)
Varicose veins and heart failure
47
Why is exchange of materials between the blood and tissues efficient?
Capillaries are one cell thick (short diffusion distance) and have pores between the cells causing the capillary walls to be permeable to water and solutes.
48
Why does blood slow down when entering capillaries
| Why is this an advantage
Because they have a small diameter
| -advantage as there is plenty of time for the exchange of materials with surrounding tissue fluid
49
Why is capillaries being branched an advantage
Numerous and highly branched :: large surface area for diffusion
50
Define myotonic contraction
The heartbeat is initiated within the muscle cells themselves, and not dependent on nervous or hormonal stimulation.
51
What are the names of the thin/thick walled collection chambers in the heart
The atria (relatively thin) located above two thicker walled pumping chambers called the ventricles
52
What does the septum prevent
Prevents the mixture of oxygenated and deoxygenated blood
53
What is cardiac muscle?
Specialist muscle only found In the heart with myogenic contraction
54
What is a benefit of cardiac muscle
Never tires :: heart continues to beat unlike voluntary muscles
55
What is the heart rate in a mammal modified by
Nervous (brain) and hormonal stimulation.
56
Describe the different sections of a heart
```
Vena Cava
Right atrium
Right AV valve (tricuspid)
Right ventricle
Left pulmonary artery
Left pulmonary veins
Left atrium
Left AV valves (bicuspid)
Left ventricle
Aorta
Semi lunar valves
Septum
Chordae tendineae
```
57
How does the heart form during embryonic development in mammals?
2 separate pumps grow together to form one overall structure the heart
58
How long does the average heartbeat last?
0.8 seconds in an adult
59
What is the name for a contraction of the atrium and relaxation of the atria
```
Contraction = atrial Systole
Relaxation = atrial Diastole
```
60
What proportion of the cardiac cycle is diastole occurring?
Approx 50%
61
Describe the 3 stages in the cardiac cycle
Atrial systole
Ventricular systole
Diastole
62
Describe atrial systole
Atrium walls contract
blood pressure in the atria increases
Pushes blood through the tricuspid and bicuspid valves down into the ventricles which are relaxed
63
Describe ventricular systole
Ventricle walls contract
Increased blood pressure in ventricles
Forces blood up through semi lunar valves out of the heart and into the pulmonary artery/aorta
64
Why does blood not flow back from the ventricles into the atria?
Because the bicuspid and tricuspid valves are closed by the rise in ventricular pressure
65
What is the role of the pulmonary artery/aorta?
Pulmonary artery= Carries deoxygenated blood to the lungs
| Aorta= carries oxygenated blood to the rest of the body
66
What is the name of the sound made by the heart?
| What causes it?
“Lub dub” sound
| Caused by the AV valves and then semi lunar valves closing
67
What is the name of the volume of blood expelled by the heart in one cycle? In one minute?
One cycle = stroke volume
| One minute = cardiac output
68
What is the cardiac output equation?
Cardiac output = stroke volume x heartbeats per minute
69
Describe the diastole
- ventricles relax
- volume of the ventricles increases and pressure decreases
- low pressure risks backflow of blood from pulmonary artery/aorta into ventricles
- tendency of backflow causes the semi-lunar valves to shut preventing backflow
- atria also relax during diastole so blood from the vena cava/ pulmonary veins enters the atria and cycle continuous
70
Describe the flow of blood through the left side of the heart
1. Left atrium relaxes and receives oxygenated blood from pulmonary vein
2. When full, the pressure forces open the bicuspid valve
3. Relaxation of the left ventricle draws blood from the left atrium
4. Left atrium contracts, pushing the remaining blood into the left ventricle through valve closing it
5. With left atrium relaxed and bicuspid valve closed, the left ventricle contracts. It’s strong muscular wall exerts High pressure
6. Pressure pushes blood up out of the heart through the semi lunar valves and into the aorta and closes the bicuspid valve, preventing backflow into the left atrium
71
What do I mean by the phrase “the two sides of the heart work together during the cardiac cycle”
The atria contract at the same time, followed millisecond later by the ventricles contracting together
72
What is a heartbeat?
The complete contraction and relaxation of the whole heart
73
What happens when the chamber of a heart contacts/relaxes during the cardiac cycle?
```
Contracts = It empties with blood
Relaxes = fills with blood again
```
74
Why do atrial walls have little muscle?
Because the blood only has to go to the ventricles
75
Why do ventricle walls have more muscle?
Because they need to generate more pressure to send the blood further, either to the lungs (pulmonary vein) or rest of the body (aorta)
76
Why does the left ventricle have a thicker muscular wall than the right ventricle
Because the left ventricle has to pump blood all round the body, whereas the right ventricle has only to pump the blood a shorter distance to the lungs
77
How do all veins operate?
All close under high blood pressure preventing blood flowing backwards
(Valves close when the blood pressure downstream is higher than the blood pressure upstream)
78
LEARN THE CHANGES IN PRESSURE IN THE HEART DIAGRAM ON PG 187
LEARN THE CHANGES IN PRESSURE IN THE HEART DIAGRAM ON PG 187
79
Define the term Sino-atrial node (SAN)
An area of the heart muscle I. The right atrium that initiated a wave of electrical excitation across the atria, to generate contraction of the heart muscle.
80
What is the SAN also known as
The pacemaker
81
Define the term Atrio-ventricular node (AVN)
The only conducting area of tissue in the wall of the heart between the atria and ventricles, through which electrical excitation passes from the atria to conducting tissue in the walls of ventricles
82
Describe in one word the contraction of cardiac muscle
Myogenic
83
Describe the role of the SAN in controlling the heartbeat
A wave of electrical stimulation arises at the SAN and spreads over both atria, so they contract together
84
Why does the electrical stimulation only spread to the ventricles via the AV node?
Because the ventricles are insulated from the atria by connective tissue, except at the AVN
85
Describe the role of the AVN in controlling the heartbeat
AVN introduces a delay in transmission of the electrical impulse and then pass the excitation down the nerve bundle of His.
86
Why is there a delay in passing the electrical excitation from the AV node to the bundle of His
Because it ensures that he atria are empties before the ventricles contract
87
What happens to the electrical excitation after passing down bundle of Hiss until it reaches the muscles of the ventricle walls?
AVN passes excitation down the bundle of His and to the apex of the heart where the excitation is transmitted to the Purkinje fibres in the ventricle walls which carry it upwards through the muscles of the ventricle walls.
88
What happens after the electrical excitation reaches the walls of the ventricles
Impulses cause the cardiac muscle In each ventricle to contract simultaneously, from the apex upwards pushing the blood up to the aorta and pulmonary artery, emptying the ventricles completely
Process repeats
89
LEARN CONTRACTION OF HEART DIAGRAM ON PG 188
LEARN CONTRACTION OF HEART DIAGRAM ON PG 188
90
What is an Electrocardiogram?
A trace of the voltage changes produced by the heart detected by the electrodes on the skin
91
Name the parts of the cardio gram that you are expected to explain
P wave
QRS complex
T wave
92
What is the P wave?
- first part of the trace
- shows the voltage change generated by the sino-atrial node, associated with the contraction (depolarisation) of the atria.
93
Why are p waves smaller than the QRS complex and T waves?
Because the atria have less muscle than the ventricles
94
What does the time between the p wave and start of the QRS complex show
The time taken for the excitation to spread from the atria to the ventricles through the atria-ventricular node
95
What does the QRS complex show?
The depolarisation and contraction of the ventricles
96
Why is the amplitude bigger of the QRS complex than the P wave
Ventricles have more muscle than the atria :: amplitude is bigger than the P wave
97
What does the T wave show?
Shows the repolarisation if the ventricle muscles.
98
What does the line between the T wave and P wave represent?
Called the isoelectric line and is the baseline of trace.
99
What would show is a person has atrial fibrillation (rapid heart)
May lack a P wave
100
What would show on an ECG if a person have a heart attack
May have a wide QRS complex
101
What would show on an ECG if a person has enlarged ventricle walls
May have a QRS complex showing greater voltage charge
102
What causes the changes in height of the ST segment and T wave
Insufficient blood being delivered to heart muscle, such as what happens to those with atherosclerosis
103
How to calculate beats per minute
1- calculate length of cycle (point to same point on ECG E.g 0.85s)
2- divide 60 by the value of 1 heart beat
E.g 60/0.85 = 71 bpm
104
Where is blood pressure highest?
| How does it change?
In the aorta and pulmonary artery (large arteries)
| It rises and falls rhythmically with ventricular contraction
105
What causes a drop in pressure in the arterioles?
Friction between the blood and vessel walls as well as the large total surface area despite their narrow lumen
106
Describe the relationships between pressure and blood flow in arteries and capillaries
Higher the blood pressure, faster the blood flows :: both pressure and speed fall as the distance from the heart increases
107
Why is pressure constantly low in the veins
Because their pressure isn’t affected by the contraction of ventricles :: remains low
108
Why does blood flow faster in the veins than in the capillaries
Because veins have a large diameter lumen :: blood flows faster despite lower pressure
109
As blood does not return the the heart rhythmically what enhances the return to the heart?
Blood returns enhanced by massaging effects of muscles around the veins
110
Define blood
Blood is a tissue made up of cells (45%) in a solution called plasma (55%)
111
What is another name for a red blood cell
Erythrocyte
112
Why are erythrocytes red?
Because they contain the pigment haemoglobin
113
What is the main purpose of the haemoglobin in erythrocytes?
Transport oxygen from the lungs to the respiring tissues
114
What shape do erythrocytes have, how is this a benefit (2 benefits)
Shape = Bioconcave disc
Benefit= surface area is larger so more oxygen diffuses across the membrane
Benefit 2= thin centre reduces the diffusion distance making gas exchange faster
115
Name another advantage of an erythrocytes based on its structure
```
Structure= no nucleus
Benefit= more room for haemoglobin, maximising the oxygen that can be carried
```
116
What is another name for a white blood cell?
| What are the two main types of white blood cell?
Name = leucocyte
Type 1= granulocytes (contain granular cytoplasm and loved nuclei)
Type 2= lymphocytes (contain clear cytoplasm and spherical nucleus)
117
What to lymphocytes produce?
Antibodies and antitoxins
118
What colour is plasma?
| What % water is plasma?
Colour= pale yellow liquid
| % =90% water
119
Describe what is found inside plasma
1-solutes (food molecules e.g glucose/amino acids)
2-waste products (e.g urea)
3-hormones
4-plasma protein (antibodies etc)
120
Define the term affinity
The degree to which two molecules are attracted to each other
121
Define the term cooperative binding
The increasing ease with which haemoglobin binds it’s second and third oxygen molecules as the confirmation of the haemoglobin molecule changes
122
Name the reversible reaction involving haemoglobin in the blood
Oxygen + haemoglobin —>< oxyhaemoglobin
4O2 + Hb —>< Hb.4O2
123
Where does haemoglobin associate and dissociate with oxygen for effective oxygen transport
Associate= where gas exchange takes place e.g at the alveoli
Disassociate= at respiring tissues such as muscle
124
How can haemoglobin perform association and disassociation
It can change its affinity for oxygen because it is able to change shape
125
Describe basic structure of haemoglobin
Each haemoglobin molecule contains 4 harm groups each containing an ion of iron
126
How many oxygen molecules can bind to one haemoglobin molecule?
One oxygen molecule can bind to each iron ion :: 4 oxygen molecules can bind to each haemoglobin molecule
127
How does the fourth oxygen molecule bind to the haemoglobin if the third does not induce a shape change?
A large increase in oxygen partial pressure is required
128
What does the term partial pressure mean?
Pressure a gas would exert if it were the only one present e.g atmospheric pressure = 100kPa and oxygen comprises of 21% of atmosphere so it’s pressure = 21 kPa
129
Why does the graph of partial pressure vs saturation of haemoglobin to with oxygen show a sigmoid curve (s shapes curve)
At very low partial pressure it is difficult for haemoglobin to bind with oxygen
At high partial pressures of oxygen the percentage saturation of oxygen is very high
130
What does the steep gradients on the oxygen dissociation curve show?
Represents the oxygen binding increasingly easily
131
Why does oxygen affinity reduce as partial pressure of oxygen decreases?
Because oxygen is readily released meeting respiratory demands
132
If the relationship between oxygen partial pressure and % saturation of haemoglobin with oxygen were linear why would high partial pressure of oxygen be dangerous?
Haemoglobin oxygen affinity would be too low and so oxygen would be readily released :: not reach respiring tissues
LOOK ON GRAPH
133
If the relationship between oxygen partial pressure and % saturation of haemoglobin with oxygen were linear why would low partial pressure of oxygen be dangerous
Haemoglobin’s oxygen affinity would be too High and oxygen would not be released in respiring tissues
LOOK ON GRAPH
134
Describe the events in the body which cause the oxygen disassociation curve
- red blood cells load oxygen in the lungs where oxygen partial pressure is high
- haemoglobin is saturated with oxygen
- cells carry oxygen as oxyhaemoglobin to respiring tissues
- at respiring tissues partial pressure of oxygen is low because oxygen is used up during respiration
- oxyhaemoglobin unloads oxygen (dissociation)
135
Why does a foetus have a higher affinity for oxygen than its mothers haemoglobin?
Foetus has haemoglobin that differs In two of the four polypeptide chains giving it a higher affinity for oxygen at the same partial pressure
136
Why is the foetus’ % haemoglobin saturation with oxygen higher than the mothers?
Which way does this shift the graph?
Their Blood flows close in the placenta :: oxygen transfers to the foetus at any partial pressure :: the percentage saturation of the foetus blood is higher than mothers
Shifts dissociation curve to the left
137
Which direction does the dissociation curve shift when animals live in low oxygen environments e.g lugworm buried in sand/mountain llamas?
Shifts to the left
138
Why is the disassociation curve of lugworms shifted to the left of humans?
Because it lives in a low oxygen environment and has a low metabolic rate :: haemoglobin need to load oxygen readily and only release it when partial pressure of oxygen is very low
139
Why is the oxygen dissociation curve shifted to the left in mountainous animals?
Bearcats haemoglobin has a higher affinity for oxygen at all oxygen pressures :: loads more oxygen in the lungs and only releases oxygen when partial pressure is low in respiring tissues
140
Define the term Bohr effect
The movement of the oxygen dissociation curve to the right at higher partial pressures of carbon dioxide, because at a given oxygen partial pressure, haemoglobin has a lower affinity for oxygen
141
What happens when carbon dioxide concentration increases?
| Describe how this affects curve?
The haemoglobin releases oxygen more readily :: at any oxygen partial pressure the haemoglobin is less saturated with oxygen :: curve moves to the right
142
What is the shift of the oxygen disassociation curve to the right when encountering increasing CO2 called?
The Bohr effect
143
What happens when the partial pressure of carbon dioxide is high to efficiency of loading and unloading
Haemoglobin has a lower affinity for oxygen :: less efficient at loading oxygen and more efficient at unloading it
144
Name the 3 ways carbon dioxide is transported
1- in solution in the plasma (5%)
2- as the hydrogen carbonate ion, HCO3- (approximately 85%)
3- Bound to haemoglobin as carbamino-haemoglobin (10%)
145
Describe how carbon dioxide is transported out of red blood cells into the plasma
1. Carbon dioxide in the blood diffuses into the red blood cell
2. Carbonic anhydride catalysed the combination of carbon dioxide with water making carbonic acid
3. carbinic acid dissociates into H+ and HCO3- ions
4. HCO3- ions diffuse out of the red blood cell into the plasma
5. Chloride shift occurs
6. H+ ions cause oxyhaemoglobin to dissociate into oxygen and haemoglobin
7. H+ ions combine with haemoglobin to form haemoglobinic acid (HHb)
8. Oxygen diffuses out of the red blood cell into the tissues
146
Describe the chrloride shift
1. To balance the outflow if negative ions and maintain electrochemical neutrality, chloride ions diffuse into the red blood cell from the plasma.
This is the chloride shift
147
Why does the H+ ions combine with the haemoglobin to form HHb?
To remove hydrogen ions and so the pH if the red blood cell does not fall
148
What does the transport of carbon dioxide out of red blood cells and into plasma show us?
- why co2 is carried in the plasma as HCO3 ions
- The Bohr effect, more CO2 produces more H+ ions so more oxygen is released from oxyhaemoglobin
- more respiration means more CO2 is present so more oxyhaemoglobin dissociates and provides oxygen to the respiring cells
149
Where does exchange between blood and body cells occur?
In the capillaries
150
What moves into cells and what moves interesting blood through capillaries
Into cell from blood= plasma solutes and oxygen
| Into blood from the cells= carbon dioxide and in the liver urea
151
How are capillaries adapted to allow exchange of materials?
- thin permeable walls
- large surface area for exchange of materials
- blood flows very slowly through capillaries allowing for time for exchange of materials
152
What does the plasma, as tissue fluid when going through capillaries supply cells with?
Solutes such as glucose, amino acids, fatty acids, salts, hormones and oxygen.
153
What is another purpose of the tissue fluid
Removes waste made by the cells
