1.2 Cardiovascular and Respiratory Systems Flashcards
(196 cards)
1
Q
What is the definition of pulmonary circuit ?
A
Circulation of blood through the pulmonary artery to the lungs and pulmonary vein back to the heart.
2
Q
What is the definition of systemic circuit?
A
Circulation of blood through the aorta to the body and vena cava back to the heart.
3
Q
What does the cardiovascular system consist of ?
A
The heart (cardiac muscle), blood vessels and the blood they contain.
4
Q
What are the two circuits of the cardiovascular system ?
A
Pulmonary circuit
Systemic circuit
5
Q
What is the path of the blood on the left side of the heart ?
A
Blood is oxygenated at the lungs and brought back to the left atria through the pulmonary vein. Oxygenated blood moves from the left atria, through the left AV valve (bicuspid) into the left ventricle to be forced out of the left side of the heart into the aorta. The aorta carries this oxygenated blood to the muscles and organs.
6
Q
What is the path of the blood on the right side of the heart?
A
Deoxygenated blood from the muscles and organs arrives back at the right atria through the vena cava. It moves from the right atria, through the right AV valve (tricuspid) into the right ventricle to be forced out of the right side of the heart into the pulmonary artery. The pulmonary artery carries this deoxygenated blood to the lungs.
7
Q
What is the definition of oxygenated blood?
A
Blood saturated with oxygen and nutrients, such as glucose.
8
Q
What is the definition of deoxygenated blood?
A
Blood depleted of oxygen, saturated with carbon dioxide and waste products.
9
Q
What is the definition of conduction system?
A
A set of structures in the cardiac muscle which create and transmit an electrical impulse, forcing the atria and ventricles to contract.
10
Q
What is the definition of myogenic?
A
The capacity of the heart to generate its own electrical impulse, which causes the cardiac muscle to contract.
11
Q
What are the 5 structures of the conduction system ?
A
- Sino-atrial node (SA node)
- Atrio-ventricular node (AV node)
- Bundle of His
- Bundle branches
- Purkyne fibres
12
Q
What is the SA node ?
A
Located in the right atrial wall, the SA node generates the electrical impulse and fires it through the atria walls, causing them to contract. The SA node is more commonly known as the pacemaker as the firing rate will determine the heart rate.
13
Q
What does the AV node do?
A
The AV node collects the impulse and delays it for approximately 0.1 seconds to allow the atria to finish contracting. It then releases the impulse to the Bundle of His.
14
Q
What does the Bundle of His do?
A
Located in the septum of the heart, the Bundle of His splits the impulse into two, ready to be distributed through each separate ventricle.
15
Q
What do the bundle branches do?
A
These carry the impulse to the base of each ventricle.
16
Q
What do the purkyne fibres do?
A
These distribute the impulse through the ventricle walls, causing them to contract.
17
Q
Explain the process of the conduction system.
A
- SA node generates the electrical impulse and fires it through the atria walls, causing them to contract.
- AV node collects the impulse and delays it for approximately 0.1 seconds to allow the atria to finish contracting. It then releases the impulse to the Bundle of His.
- Bundle of His splits the impulse into two, ready to be distributed through each separate ventricle.
- Bundle Branches carry the impulse to the base of each ventricle.
- Purkyne fibres distribute the impulse through the ventricle walls, causing them to contract.
18
Q
What does the cardiac cycle refer to?
A
The process of cardiac muscle contraction and the movement of blood through its chambers.
19
Q
How long does one complete cardiac cycle take?
A
0.8 seconds.
20
Q
What are the two distinct phases of the cardiac cycle?
A
Diastole
Systole
21
Q
What is the definition of cardiac diastole?
A
The relaxation phase of cardiac muscle where the chambers fill with blood.
22
Q
What is the definition of cardiac systole?
A
The contraction phase of cardiac muscle where blood is forcibly ejected into the aorta and pulmonary artery.
23
Q
What happens during the diastole phase of the cardiac cycle?
A
As the atria and then the ventricles relax, they expand drawing blood into the atria.
The pressure in the atria increases opening AV valves.
Blood passively enters the ventricles.
SL valves are closed to prevent blood from leaving the heart.
24
Q
What happens during the atrial systole phase of the cardiac cycle?
A
The atria contract, forcing remaining blood into the ventricle.
25
What happens during the ventricular systole phase of the cardiac cycle?
The ventricles contract, increasing the pressure closing the AV valves to prevent backflow into the atria.
SL valves are forced open as blood is ejected from the ventricles into the aorta and pulmonary artery.
26
What is the definition of heart rate?
The number of times the heart beats per minute.
27
What is the unit of heart rate?
bpm
28
What is the average resting heart rate?
72bpm
29
What is heart rate affected by?
Genetics
Gender
Fitness
30
How does being an elite athlete affect heart rate?
It would be expected for an elite endurance athletes to have a resting heart rate lower than 60bpm.
31
What is the definition of bradycardia?
A resting heart rate below 60bpm.
32
What is cardiac hypertrophy?
An increase in size of the cardiac muscle, which often happens for elite endurance athletes.
33
How can you find maximal heart rate?
Subtracting your age from 220.
34
What is the definition of stroke volume?
The volume of blood ejected from the left ventricle per beat.
35
What is the average stroke volume?
70ml
36
What is the unit for stroke volume?
ml
37
What is the definition of venous return?
The return of the blood to the right atria through the veins.
38
What are the two factors that stroke volume is dependent on?
1. Venous return - the greater the return of blood to the heart, the greater the volume of blood available in the ventricles for ejecting.
2. Ventricular elasticity and contractility refers to the degree of stretch in the cardiac muscle fibres. - The greater the stretch, the greater the force of contraction, which will raise stroke volume.
39
What is the definition of cardiac output?
The volume of blood ejected from the left ventricle per minute.
40
What is the unit for cardiac output?
l/min
41
What is the average cardiac output?
5l/min
42
How do you find stroke volume?
Heart rate x stroke volume
43
What is the definition of sub-maximal exercise?
A low-to-moderate intensity of exercise within a performer’s aerobic capacity.
44
What is the definition of maximal exercise?
A high intensity of exercise above a performer’s aerobic capacity that will induce fatigue.
45
Describe what a graph would like that shows heart rate response to increasing exercise intensity.
1. An initial anticipatory rise in heart rate prior to exercise due to the release of the hormone adrenaline.
2. A rapid increase in heart rate at the start of exercise to increase blood flow and oxygen delivery in line with exercise intensity.
3. A steady state in heart rate throughout the sustained intensity exercise as oxygen supply meets demand.
4. An initial rapid decrease in heart rate as recovery is entered and the action of the muscle pump reduces.
5. A more gradual decrease in heart rate to resting levels.
46
What is the definition of the Frank-Starling mechanism?
Increased venous returns leads to an increased stroke volume, due to an increased stretch of the ventricle walls and therefore force of contraction.
47
What two factors enable the stroke volume to increase?
1. Increased venous return
2. The Frank-Starling mechanism.
48
How does an increased venous return increase stroke volume?
During exercise, venous return increases, meaning there is a greater volume of blood returning to the heart and filling ventricles. This is due to the squeezing action of muscular contraction around the veins known as muscle pump.
49
How does the Frank-Starling mechanism increase stroke volume?
The Frank-Starling mechanism shows us how SV is dependent on venous return. An increased volume of blood returning to the heart leads to an increased end-diastolic in the ventricles and therefore greater stretch on the ventricle walls. This greater stretch increases the force of ventricular contraction, ejecting a larger volume of blood from the ventricles. The lower the heart rate, the more time available to maximise this effect, hence why we see a greater exercising stroke volume in trained athletes.
50
Why does stroke volume reach a plateau during sub-maximal intensity?
Increases heart rate towards maximal intensities does not allow enough time for the ventricles to completely fill with blood in the diastolic phase. This limits the Frank-Starling mechanism.
51
How is the heart rate regulated?
The automatic nervous system (ANS) involuntarily regulates heart rate and determines the firing rate of the SA node. The higher the firing rate of the SA node, the higher the heart rate. From the medulla oblongata in the brain, the cardiac control centre (CCC) received information from the sensory nerves and sends direction through motor nerves to change heart rate.
52
What are the three main sources of information that determine the actions of the CCC?
1. Neural control
2. Intrinsic control
3. Hormonal control
53
What are the three neural control factors that help the determine the actions of the CCC?
Chemoreceptors- located in the muscles, aorta and carotid arteries inform the CCC of chemical changes in the blood stream, such as increased levels of carbon dioxide and lactic acid.
Proprioceptors - located in the muscles, tendons and joints to inform the CCC of motor activity.
Baroreceptors - located in the blood vessels walls inform the CCC of increased blood pressure.
54
What are the two intrinsic control factors that help to determine the actions of the CCC?
1. Temperature change will affect the viscosity (thickness) of the blood and speed of the nerve impulse transmission.
2. Venous return changes will affects the stretch in the ventricle walls, forces of ventricular contraction and therefore stroke volume.
55
What is the hormonal control factor that helps to determine the actions of the CCC?
Adrenaline and noradrenaline are released from the adrenal glands, increasing the force of ventricular contraction (therefore stroke volume) and increasing the spread of electrical activity through the heart (therefore heart rate)
56
What is the definition of the cardiac control centre?
A control centre in the medulla oblongata responsible for heart rate regulation.
57
What is the definition of the sympathetic nervous system?
It is part of the autonomic nervous system responsible for increasing heart rate, specifically during exercise.
58
What is the definition of parasympathetic nervous system?
It is part of the autonomic nervous system responsible for decreasing heart rate, specifically during recovery.
59
What is the vascular system?
The dense network of blood vessels and the blood which they carry in one direction every corner of the human body.
60
What is the function of the vascular system?
It ensures oxygen and nutrients are delivered to all respiring cells for energy production, and waste is removed efficiently.
61
What are the 3 functions of the blood?
Transports nutrients such as oxygen and glucose.
Protects and fight disease.
Maintain the internal stability of the body (homeostasis) and regulates temperature.
62
What are the three main types of blood vessel?
Arteries
Veins
Capillaries
63
What do arteries and arterioles do?
Transport oxygenated blood from the heart to the muscles and organs.
64
What is the main artery ?
The aorta, which carries blood at high pressure directly from the left ventricle.
65
What does vasodilate mean?
Widening of arteries, arterioles and per-capillary sphincters.
66
What does vasoconstrict mean?
Narrowing of arteries, arterioles and per-capillary sphincters.
67
What is the structure of arteries ?
Larger layer of smooth muscle and elastic tissue to cushion and and smooth the pulsating blood flow.
68
What is the structure and function of arterioles?
Large layer of smooth muscle allowing both vessels to vasodilate and vasoconstrict to regulate blood flow and control blood pressure.
They have a ring of smooth muscle surrounding the entry of a capillary bed called pre-capillary sphincters. These dilate and constrict to control the blood flow through the capillary bed.
69
What is the function is capillaries ?
They bring the blood slowly into close contact with the muscle and organ cells from gaseous exchange.
70
What is the structure of capillaries ?
Capillary wall are composed of a single layer of cells, thin enough to allow gas, nutrient and waste exchange.
71
What is the function of veins and venules?
They transport deoxygenated blood from the muscles and organs to the heart.
Venules leaving the capillary bed reconnect to form veins.
72
What is the main vein?
Vena cava, which carries slow-moving blood at low pressure back to the right atria (largely against gravity).
73
What is the structure of veins and venules?
They have a small layer of smooth muscle, allowing them to venodilate and venoconstrict to maintain the slow flow of blood towards the heart.
Veins have one-way pocket valves, which prevent back-flow of blood as it travels against gravity.
74
What are the 5 mechanisms of venous return?
1. Pocket valves - one-way valves located in the veins which prevent backflow of blood.
2. Smooth muscle - the layer of smooth muscle in the vein wall venoconstricts to create venomotor tone which aids the movement of blood.
3. Gravity - blood from the upper body , above the heart, is helped to return by gravity.
4. Muscle pump - during exercise, skeletal muscles contract, compressing the veins located between them, squeezing the blood back to the heart.
5. Respiratory pump - During inspiration and expiration, a pressure difference between the thoracic and abdominal cavity is created, squeezing the blood back to the heart. As exercise increases respiratory rate, the respiratory pump is maximised.
75
What is the definition of inspiration?
Drawing of air into the lungs
76
What is the definition of expiration ?
Expelling of air from the lungs
77
What is the definition of blood pooling?
Accumulation of blood in the veins due to gravitational pull and lack of venous return.
78
What is the definition of active recovery?
Low-intensity activity post exercise to maintain elevated heart and breathing rates.
79
Why can we sometimes feel lightheaded and dizzy after exercise?
As we finish exercising and enter recovery, cardiac output is till high. However, there may not be sufficient pressure to return the vast quantity of blood back to the heart. This can cause feelings of being lightheaded or dizzy.
80
Why do we sometimes experience ‘heavy legs’ after exercise?
The blood may sit in pockets balances and pool due to there not being sufficient pressure to return through vast quantity of blood back to the heart.
81
How can you combat feeling lightheaded and experiencing ‘heavy legs’ after exercise?
To combat them and maintain grouse return, it is essential to complete an active recovery (cool down). This low-intensity exercises maintains the muscle and respiratory pump to aid the return of blood to the heart.
82
How does the volume of cardiac output change when exercising ?
Cardiac output at rest is about 5l/min but during intense exercises, this can rise to more than 20l/min.
83
During exercise, how does the distribution of cardiac output change?
At rest, our body primarily serves to digest, filter and excrete. Therefore, the vast majority of the oxygen and nutrient-rich blood is required sound the organs (75%).
As we start to exercise, demand from the muscles for oxygen and nutrients steps up and the more intense the exercise, the higher the demand (85% at maximum effort).
84
The redistribution of blood flow from one area of the body to another is controlled by what?
The vascular shunt mechanism
85
What is the definition of the vascular shunt mechanism?
The redistribution of cardiac output around the body from rest to exercise which increases the percentage of blood flow to the skeletal muscles.
86
What is the definition of arterioles?
Blood vessels carrying oxygenated blood from the arteries to the capillary beds, which can vasodilate and vasoconstrict to regulate blood flow.
87
What is the definition of pre-capillary sphincters?
Rings of smooth muscle at the junction between arterioles and capillaries, which dilate or constrict to control blood flow through the capillary bed.
88
What can pre-capillary sphincters do to control blood flow?
They can constrict, which limits blood flow through the capillary bed.
They can dilate, which maximises blood flow into the capillary bed.
89
At rest, a high percentage of cardiac output is distributed to the organs, whereas a very low percentage is distributed to the muscles. How is this allowed to happen ?
Arterioles to the organs vasodilate, increasing blood flow, while arterioles to the muscles vasoconstrict to limit blood flow.
Pre-capillary sphincters dilate, opening up the capillary beds to allow more blood flow to the organ cells, while constricting, closing the capillary beds to the muscle cells.
90
What controls the vascular shunt mechanism?
The vasomotor control centre (VCC).
91
Where is the vasomotor control centre located?
The medulla oblongata of the brain
92
What is vasomotor tone?
The smooth muscle in the walls of arterial blood vessels is always in a slight state of constriction.
93
What is the definition of vasomotor control centre?
The control centre in the medulla oblongata responsible for cardiac output distribution
94
What is the definition of vasomotor tone ?
The partial state of smooth muscle constriction in the arterial walls.
95
What happens when the VCC receives sensory information?
The VCC alters the level of stimulation sent to the arterioles and pre-capillary sphincters at different sites in the body.
96
Where does the VCC receive information from?
Chemoreceptors - regarding chemical changes, such as carbon dioxide and lactic acid rising during exercise.
Baroreceptors - regarding pressure changes on the arterial walls.
97
When sympathetic stimulation increases, what happens?
Sympathetic stimulation increases to vasoconstrict arterioles and pre-capillary sphincters to limit blood flow to an area, such as the muscles as rest.
98
When sympathetic stimulation decreases, what happens?
Sympathetic stimulation decreases to vasodilate arterioles and pre-capillary sphincters to increase blood flow to an area, such as the muscles during exercise.
99
What does the respiratory system consist of?
nose
series of airways
lungs
respiratory muscles
100
What are the 2 main functions of the respiratory system?
1. Pulmonary ventilation - the inspiration and expiration of air
2. Gaseous exchange
a) external respiration - the movement of oxygen into the blood stream and carbon dioxide into the lungs
b) internal respiration - the release of oxygen to respiring cells for energy production and collection of waste products
101
What is the definition of alveoli?
clusters of tiny air sacs covered in a dense network of capillaries, which together serve as the external site for gaseous exchange
102
What is the definition of gaseous exchange?
The movement of oxygen from the alveoli into the blood stream and carbon dioxide from the blood stream into the alveoli.
103
What is the structure of the passageways within the respiratory system and why?
They have a mucous membrane and ciliated cells (covered in tiny hairs), which moisten, warm and filter the air before entering the lungs.
104
What is the flow of air in the respiratory system?
Air is drawn into the nasal cavity through the nose and travels down the pharynx, larynx and trachea.
The trachea then divides into the left and right bronchi as they enter the lung cavity.
The right lung has three lobes but the left lung has two to accommodate the heart.
The bronchi subdivide into smaller bronchioles and end in alveolar ducts. This is the entrance for air to move into the alveoli.
105
What is the structure of the alveolar walls and why?
They are a single cell thick and lined with fluid. With very slow blood flow and very thin, moist walls that are in extremely close contact, they are the perfect conditions for gaseous exchange.
106
What is the definition of haemoglobin?
An iron-rich globular protein in red blood cells, which can chemically combine with four oxygen molecules to form oxyhaemoglobin.
107
What is the definition of oxygen?
the essential gas required for aerobic energy production in the muscle cells.
108
What is the definition of carbon dioxide?
The waste product of aerobic energy production in the muscle cells.
109
What percentage of blood is made of cells?
45%
110
What percentage of blood is made of plasma?
55%
111
How can oxygen be transported?
1. carried with haemoglobin (Hb) in the red blood cells (97%)
2. carried with blood plasma (3%)
112
How can carbon dioxide be transported?
1. dissolved in water and carried as carbonic acid (70%)
2. carried within haemoglobin (23%)
3. dissolved in blood plasma (7%)
113
What is the definition of breathing rate?
the number of inspirations or expirations (breaths) per minute
114
What is the average resting breathing rate?
12-15 breaths/minute
115
What is the unit for breathing rate?
breaths/minute
116
What is the definition of tidal volume?
the volume of air inspired or expired per breath
117
What is the average resting tidal volume?
500ml
118
What is the unit for tidal volume?
ml
119
What letter is used to represent breathing rate?
f
120
How can tidal volume be affected?
size of lungs and thoracic cavity
age
gender
fitness
any respiratory conditions such as bronchitis
121
Of the average 500ml tidal volume, where is it used?
350ml reaches the alveoli for gaseous exchange
150ml remains in the airways and is known as dead space
122
What is the definition of minute ventilation?
the volume of air inspired or expired per minute
123
What is the average resting minute ventilation?
6-7.5l/minute
124
What is the unit for minute ventilation?
l/min
125
How do you find minute ventilation?
TV x f = VE
126
What is the role of the respiratory system during exercise?
As we start to exercise, the demand for oxygen by the muscles rapidly increases. It is the role of the respiratory system to increase the supply of air to the alveoli and therefore oxygen for gaseous exchange.
The response of the respiratory system will depend in the intensity of the exercise.
127
How does breathing rate change in response to exercise?
Breathing rate increases in proportion to the intensity of exercise until we approach our maximum of around 50-60 breaths per minute.
In sub-maximal, steady-state exercise, breathing rate can plateau due to the supply of oxygen meeting the demand from the working muscles.
128
How does tidal volume change in response to exercise?
Tidal volume increases initially in proportion to exercise intensity at sub-maximal intensities, up to about 3 litres.
Tidal volume reaches a plateau during sub-maximal intensity because increased breathing rate towards maximal intensities does not allow enough time and requires too much muscular effort for maximal inspirations or expirations.
129
How does minute ventilation change in response to exercise?
Minute ventilation is the product of breathing rate and tidal volume and therefore the response to exercise and recovery is a combination of the two. Minute ventilation increases in line with exercise intensity, whereby breathing rate and tidal volume will both increase.
130
What would a graph of % of maximal oxygen uptake to minute ventilation look like?
1. an initial anticipatory rise in VE prior to exercise due to the release of the hormone adrenaline
2. a rapid increase in VE at the start of exercise due to increased breathing rate and tidal volume to increase oxygen delivery and waste removal in line with exercise intensity.
3. a steady state VE throughout the sustained intensity exercise as oxygen supply meets demand.
4. an initially rapid and then more gradual decrease in VE to resting levels as recovery is entered and the demand for oxygen dramatically reduces.
131
During maximal intensity exercise, why does VE not plateau?
Exercise intensity continues to increase. There is a growing demand for oxygen and waste removal, which VE must continually strive to meet.
132
Where are the lungs situated?
In the thoracic cavity and encased in pleural sacs.
133
What is used to reduce friction during inspiration and expiration?
A layer of pleural fluid between the lung and the pleural membranes.
134
What kind of process is breathing?
Breathing is a mechanical process through which muscles contract to cause a movement of the rib cage and sternum, which in turn changes the volume and pressure of the thoracic cavity. It is the change in pressure which causes air to rush in or out of the lungs.
135
What type of process is inspiration?
active
136
What two muscles are largely responsible for inspirations at rest, which contract to increase the volume of the thoracic cavity?
1. the external intercostals, which lie between each rib, contract lifting the rib cage and sternum up and out.
2. the diaphragm, which lies underneath the lungs and separates the thoracic and abdominal cavity, contracts and flattens.
137
How does inspiration work at rest?
As the external intercostals and diaphragm contract, the volume inside the thoracic cavity and space inside the lungs increases. This lowers the pressure below the atmosphere outside the body. All gases move from an area of high to low pressure, as air rushes into the lungs.
138
During exercise, what can tidal volume increase to?
from 0.5litres to 3 litres
139
In addition to the external intercostals and
diaphragm, what are the additional inspiratory muscles that can be recruited to give a larger force of contraction for inspiration during exercise?
1. sternocleidomastoid
2. pectoralis minor
140
How are the sternocleidomastoid and pectoralis minor used for inspiration during exercise?
The greater force of contraction creates a greater up and outward movement of the rib cage and sternum. The greater movement increases the volume and decreases the pressure inside the thoracic cavity more than at rest. This increases the depth of breathing and therefore the volume of air inspired.
141
What type of process is expiration at rest?
passive
142
What are the two muscles responsible for inspiration at rest, which relax into their natural state, decreasing the volume of the thoracic cavity?
1. the external intercostals relax, lowering the rib cage and sternum down and in.
2. the diaphragm relaxes and returns to its dome shape.
143
How is one expiration done?
As the external intercostals and diaphragm relax, the volume inside the thoracic cavity and space inside the lungs decrease. This increases the pressure above the atmosphere outside the body; therefore, air is pushed out of the lungs.
144
When exercise begins, what type of process does expiration become?
active
145
What are the two muscles that are recruited to give a larger force of contraction for expirations during exercise?
1. internal intercostals
2. rectus abdominis
146
How are the internal intercostals and rectus abdominis used to help with expiration during exercise?
They cause a greater force of contraction. This creates a greater down and inward movement of the rib cage and sternum. The greater movement decreases the volume and increases the pressure inside the thoracic cavity more than at rest. This increases the rate of breathing and therefore the overall volume of air expired per minute.
147
What is the definition of the respiratory control centre (RCC)?
A control centre in the medulla oblongata responsible for respiratory regulation.
148
What is the definition of the inspiratory centre (IC)?
A control centre within the RCC responsible for inspiration.
149
What is the definition of the expiratory centre (EC)?
A control centre within the RCC responsible for expiration.
150
What is respiratory control?
As a period of exercise or recovery appears, the brain gets involved to regulate breathing rate.
151
What does the respiratory control centre do?
The RCC received information from the sensory nerves and sends direction through motor nerves to change the rate of respiratory muscle contraction.
152
At rest, what is responsible for the rhythmic cycle of breathing?
the IC
153
Nerves impulses are generated and therefore stimulate the inspiratory muscle, causing them to contract via what nerves?
1. intercostal nerve to the external intercostals
2. phrenic nerve to the diaphragm
154
How do nerve impulses regulate respiratory levels at rest?
Nerves impulses are generated and stimulate the inspiratory muscles, causing them to contract via intercostal nerve to the external intercostals and via the phrenic nerve to the diaphragm. This causes the thoracic cavity volume to be increased, lowering lung air pressure. Approximately 500ml of air will be inspired. After approximately 2 seconds, stimulation stops and the inspiratory muscles relax. lung tissue recoil, causing a passive expiration.
155
Is the expiratory centre active or inactive during rest and why?
It is inactive at rest due to the natural relaxation of the diaphragm and external intercostals.
156
During exercise, what happens to breathing rate and depth and why?
Breathing rate and depth must be increased to meet the rising demands for oxygen and carbon dioxide removal.
157
During exercise, what type of information is fed to the RCC?
Chemical information
Neural stimuli
158
What happens in RCC in response to exercise?
Sensory nerves relay the information to the RCC, where a response is initiated by both the IC and EC.
159
What chemical information is fed to the RCC during exercise?
Chemoreceptors located in the aorta and carotid arteries pick up an increase in blood activity, increase in carbon dioxide concentration and decrease in oxygen concentration.
160
What neural stimuli are fed to the RCC during exercise?
Thermoreceptors inform of an increased blood temperature.
Proprioceptors inform of motor activity in the muscles and joints.
Baroreceptors, located in the lung tissue and bronchioles, inform of the state of lung inflation.
161
Chemoreceptors, thermoreceptors and proprioceptors inform the IC that the body is doing exercise. What does this then cause?
It is increases stimulation of the diaphragm and external intercostals to contract with more force.
The IC also recruits the additional inspiratory muscles, sternocleidomastoid and pectoralis minor, to contract. This greater force of contraction increases the depth of inspiration.
162
Baroreceptors inform the EC on the extent of lung inflation. How does this affect inspiration?
If the tissue begins to become excessively stretch, the EC stimulates additional expiratory muscles, intercostals and rectus abdominis, to contract. This reduces the volume of the thoracic cavity, increasing the lung air pressure. This causes a forced expiration, which reduces the time available for inspiration.
163
As exercise intensity increases, what happens to the IC and EC?
As exercise intensity increases, the combination of IC and EC control leads to an increased breathing rate and decreased breathing depth to maximise efficient respiration.
164
What is the definition of partial pressure?
the pressure exerted by an individual gas held in a mixture of gases
165
What is the definition of diffusion?
the movement of gases across a membrane down a gradient from an area of high pressure (or concentration) to an area of low pressure (or concentration)
166
What is the definition of diffusion gradient?
the difference in areas of pressure (or concentration) from one side of a membrane to the other
167
What is deoxygenated blood?
The blood that arrives through the capillaries that surround the alveoli is said to be deoxygenated as the oxygen has been used at the tissues for respirations and carries the waste product carbon dioxide.
168
What is the air inspired into the lungs like? What does this mean?
The air inspired into the alveoli is oxygen-rich at sea level and has very low levels of carbon dioxide. This presents gases either side of a double membrane that have different pressures.
169
The partial pressures of what gases have been recorded at various sites in the body?
oxygen
carbon dioxide
170
We are primarily concerned with the partial pressure of oxygen and of carbon dioxide in which two sites in the body?
1. the external site for gaseous exchange between the alveoli and the blood capillary membrane.
2. the internal site for gaseous exchange between the blood capillary and muscle cell membrane.
171
What does gaseous exchange refer to?
the movement of gases across a membrane
172
The steeper the diffusion gradient, the greater the rate of what?
the greater the rate of gaseous exchange
173
What does an imbalance of the partial pressure of oxygen and carbon dioxide cause? How does exercise affect this?
The imbalance of the partial pressure of oxygen and carbon dioxide on either side of the alveolar-capillary membrane and capillary-tissue membrane causes a pressure gradient at rest. The onset of exercise changes the conditions within the bloodstream and muscle cells and steepens the diffusion gradient, causing a greater rate of diffusion.
174
What is external respiration?
The exchange of gases at the lungs between deoxygenated blood that arrives in the capillaries with the oxygen-rich atmospheric air held in the alveoli.
175
What is the movement of oxygen during external respiration?
Oxygen moves from the high partial pressure in the alveoli into the low partial pressure capillary blood down the diffusion gradient. The haemoglobin molecules associate (combine) with the oxygen molecules to form oxyhaemoglobin as the blood passes the alveoli. This ensures the blood that leaves the lungs has been fully saturated with oxygen.
176
What is the movement of carbon dioxide during external respiration?
Carbon dioxide moves from the high partial pressure in the carbon-rich capillary blood into the low partial pressure alveoli down the diffusion gradient. Although the diffusion gradient is small, carbon dioxide can cross the membrane much more rapidly.
177
What is internal inspiration?
the exchange of gases at the muscle cells between the oxygenated blood that arrives in the capillaries with the carbon dioxide producing muscle cells
178
What is the movement of oxygen during internal respiration?
Oxygen moves from the high partial pressure in the capillary blood into the low partial pressure muscle cell down the diffusion gradient. The haemoglobin molecules dissociate (release) the oxygen for diffusion as they pass the muscle cells.
179
What is the movement of carbon dioxide during internal respiration?
Carbon dioxide moves from the high partial pressure in the muscle cells into the low partial pressure capillary blood down the diffusion gradient. This ensures the blood that leaves the muscle cells has been saturated with waste products ready for removal.
180
During exercise, what happens to our respiring muscles and what does this cause?
During exercise, our respiring muscles demand a far greater volume of oxygen and produce a greater volume of carbon dioxide. This means minute ventilation and cardiac output both increase to cater for this demand as the blood leaving the muscle tissue becomes further deoxygenated.
181
During exercise, what happens to the diffusion of oxygen and carbon dioxide for external respiration?
During exercise, the muscle tissues use a greater volume of oxygen for aerobic respiration and consequently produce a greater volume of carbon dioxide. This means the deoxygenated blood that returns to the lungs from the right ventricle has a lower partial pressure of oxygen and a higher partial pressure of carbon dioxide than at rest.
The oxygen diffusion gradient steepens and oxygen diffuses from the high partial pressure in the alveoli to the lower partial pressure in the capillary blood at a greater rate.
The carbon dioxide diffusion gradient steepens and carbon dioxide diffuses from the higher partial pressure in the capillary blood to the low partial pressure in the alveoli at a greater rate.
182
During exercise, what happens to the diffusion of oxygen and carbon dioxide for internal respiration?
The muscle tissue's demand for oxygen increases in line with exercise intensity to produce energy through aerobic respiration. The waste product is carbon dioxide. Therefore, the more intense the exercise, the lower the partial pressure of oxygen and the higher the partial pressure of carbon dioxide in the muscle tissue.
The oxygen diffusion gradient steepens and the oxygen diffuses from the high partial pressure in the capillary blood to the lower partial pressure in the muscle cell.
The carbon dioxide diffusion gradient steepens and carbon dioxide diffuses from the higher partial pressure in the muscle cell to the low partial pressure in the capillary blood.
183
What is the definition of association?
the combining of oxygen with haemoglobin to form oxyhaemoglobin
184
What is the definition of dissociation?
the release of oxygen from haemoglobin for gaseous exchange
185
What is the definition of the oxyhaemoglobin dissociation curve?
a graph showing the relationship between the partial pressure of oxygen and the percentage saturation of haemoglobin
186
How many oxygen molecules can one haemoglobin carry?
4 oxygen molecules
187
What determines the amount of oxygen that associates with haemoglobin?
the partial pressure of oxygen
188
What is the relationship shown in the oxyhaemoglobin curve?
The amount of oxygen that associates with haemoglobin is determined by the partial pressure of oxygen. It readily associates with oxygen when the partial pressure of the oxygen is high to form oxyhaemoglobin. This occurs at the alveoli where the oxygen partial pressure tops 100mmHg and so the blood leaving the alveoli is almost 100% saturated with oxygen. As the partial pressure of the oxygen decreases, the haemoglobin more readily dissociates with oxygen, releasing it to the respiring tissues, such as the muscles.
189
Using values, describe how the oxyhaemoglobin curves varies at rest?
At rest, the partial pressure of oxygen in the muscle tissue is 40mmHg and about 25% of oxygen has dissociated from the haemoglobin and become available for diffusion into the muscle cells. About 75% of the oxygen remains associated with haemoglobin in the blood stream.
190
Using values, describe how the oxyhaemoglobin curves varies during exercise?
As exercise intensity increases, the partial pressure of oxygen lowers in the muscle cell and more oxygen dissociates from the haemoglobin for diffusion.
For example, at a partial pressure of oxygen of 15mmHg in the muscle tissue, about 75% of oxygen has dissociated from haemoglobin and become available for diffusion into the muscle cells.
191
What is the definition of the Bohr Shift?
a move in the oxyhaemoglobin curve to the right caused by increased acidity in the blood stream
192
During exercise, what 3 things happen to the muscle tissue? What does this cause?
1. it increases in temperature
2. it increased production of carbon dioxide
3. it increases production of lactic acid and carbonic acid
These factors move the oxyhaemoglobin dissociation curve to the right.
193
How does the Bohr Shift work?
1. During exercise, the muscle tissue increases in temperature, increases production of carbon dioxide and increases production of lactic acid and carbonic acid.
2. These factors move the oxyhaemoglobin dissociation curve to the right.
3. At any given partial pressure of oxygen for exercising muscle tissue, the percentage saturation of oxyhaemoglobin is far lower and therefore dissociation of oxygen to respiring tissues greater.
4. This enhances the volume of oxygen available for diffusion and therefore aerobic energy production during exercise.
194
In recovery, what happens to the oxyhaemoglobin dissociation curve?
In recovery, the oxyhaemoglobin dissociation curve shifts back to the left, returning haemoglobin saturation with oxygen to its original relationship.
This allows a greater uptake or association of oxygen to haemoglobin at the alveoli, which is essential to oxygenate the blood stream flushing out waste products and returning the body to a pre-exercise state.
195
How does the sympathetic nervous system send information to change heart rate?
If an increase in heart rate is required, the sympathetic nervous system is actioned, releasing adrenaline, noradrenaline and sending information to the SA node via the accelerator (or cardiac) nerve.
196
How does the parasympathetic nervous system send information to change heart rate?
If a decrease in heart rate is required, the parasympathetic nervous system is actioned to inhibit these effects via the vagus nerve.
