Applied anatomy and physiology Flashcards
(346 cards)
1
Q
What is the cardiovascular system?
A
The cardiovascular system is the body’s transport system, including the heart and blood vessels.
2
Q
Why is an efficient cardiovascular system important during exercise?
A
It is important because the heart pumps blood to deliver oxygen to working muscles and gather waste products.
3
Q
What additional function does the cardiovascular system serve during exercise?
A
It transports heat, a by-product of exercise, to the skin for cooling down.
4
Q
What will this chapter provide an overview of?
A
This chapter will give a brief overview of the structure of the cardiovascular system.
5
Q
What divides the heart into two parts?
A
The heart is divided into two parts by a muscular wall called the septum.
6
Q
What are the two chambers in each part of the heart?
A
Each part contains two chambers - an atrium and a ventricle.
7
Q
How do the sizes of the atria compare to the ventricles?
A
The atria are smaller than the ventricles.
8
Q
What is the primary function of the atria?
A
The atria push the blood down into the ventricles.
9
Q
Why do the atria have thinner muscular walls?
A
Atria do not require much force to push blood down into the ventricles.
10
Q
Why do the ventricles have thicker muscular walls?
A
Ventricles need to contract with greater force to push blood out of the heart.
11
Q
Which side of the heart is larger and why?
A
The left side of the heart is larger as it needs to pump blood all around the body.
12
Q
What does the right side of the heart do?
A
The right side pumps deoxygenated blood to the lungs.
13
Q
Why is the right side of the heart in close proximity to the lungs?
A
The right side pumps deoxygenated blood to the lungs which are in close proximity to the heart.
14
Q
Diagram of the heart
A
15
Q
What does the vena cava do?
A
The vena cava brings deoxygenated blood back to the right atrium.
16
Q
What is the function of the pulmonary vein?
A
The pulmonary vein delivers oxygenated blood to the left atrium.
17
Q
What does the pulmonary artery do?
A
The pulmonary artery leaves the right ventricle with deoxygenated blood to go to the lungs.
18
Q
What is the role of the aorta?
A
The aorta leaves the left ventricle with oxygenated blood leading to the body.
19
Q
What is the function of the heart valves?
A
The heart valves regulate blood flow by ensuring it moves in only one direction.
20
Q
How do heart valves function?
A
They open to allow blood to pass through and then close to prevent back flow.
21
Q
Where is the tricuspid valve located?
A
The tricuspid valve is located between the right atrium and right ventricle.
22
Q
Where is the bicuspid valve located?
A
The bicuspid valve is located between the left atrium and left ventricle.
23
Q
What are the semi-lunar valves?
A
The semi-lunar valves can be found between the right and left ventricles and the pulmonary artery and aorta.
24
Q
What is the cardiac conduction system?
A
The cardiac conduction system is a group of specialised cells located in the wall of the heart which send electrical impulses to the cardiac muscle, causing it to contract.
25
How does blood flow through the heart?
Blood flows through the heart in a controlled manner, in through the atria and out through the ventricles.
26
What is myogenic heart muscle?
Heart muscle is described as being myogenic as the beat starts in the heart muscle itself with an electrical signal in the sinoatrial node (SAN).
27
What happens when the electrical impulse spreads from the SAN?
The electrical impulse spreads through the walls of the atria, causing them to contract and forcing blood into the ventricles.
28
What is the role of the atrioventricular node (AVN)?
The AVN delays the transmission of the cardiac impulse for approximately 0.1 seconds to enable the atria to fully contract before ventricular systole begins.
29
What is the bundle of His?
The bundle of His is a group of specialised fibres located in the septum separating the two ventricles.
30
What happens after the impulse passes through the bundle of His?
The bundle of His branches out into two bundle branches and then moves into smaller bundles called purkinje fibres which spread throughout the ventricles causing them to contract.
31
What does myogenic mean?
The capacity of the heart to generate its own impulses.
32
What is the sinoatrial node?
A small mass of cardiac muscle found in the wall of the right atrium that generates the heartbeat.
## Footnote
It is more commonly called the pacemaker.
33
What is the function of the atrioventricular node?
This node relays the impulse between the upper and lower sections of the heart.
34
What is systole?
When the heart contracts.
35
What is the bundle of His?
A collection of heart muscle cells that transmit electrical impulses from the AVN via the bundle branches to the ventricles.
36
What are Purkinje fibres?
Muscle fibres that conduct impulses in the walls of the ventricles.
37
Diagram of cardiac conduction system
38
What does the mnemonic S A A B P V stand for?
Sally always aims balls past Vicky, summarising the conduction system as five main points: SAN, Atrial systole, AVN, Bundle of His, Purkinje fibres, Ventricular systole.
39
What is the first point in the conduction system?
SAN
40
What is the second point in the conduction system?
Atrial systole
41
What is the third point in the conduction system?
AVN
42
What is the fourth point in the conduction system?
Bundle of His
43
What is the fifth point in the conduction system?
Purkinje fibres
44
What is the final point in the conduction system?
Ventricular systole
45
What are atrial and ventricular systole?
Atrial systole is the contraction of the atria, which pushes blood into the ventricles. Ventricular systole is the contraction of the ventricles, which pumps blood out of the heart into the pulmonary artery and aorta.
46
What is the role of the conduction system in the heart?
The conduction system ensures that heart rate increases during exercise to allow the working muscles to receive more oxygen.
47
Where does the heart generate its impulses?
The heart generates its own impulses from the SAN (Sinoatrial Node).
48
What controls the rate of cardiac impulses?
The rate at which cardiac impulses are fired can be controlled by three main mechanisms: Neural control mechanism, Chemoreceptors, Baroreceptors.
49
What are the three main mechanisms that control cardiac impulse rate?
Chemoreceptors, Baroreceptors and Proprioreceptors
50
What is the role of the sympathetic nervous system in neural control?
It stimulates the heart to beat faster.
51
What is the role of the parasympathetic nervous system in neural control?
It returns the heart to its resting level.
52
What are the two parts of the nervous system?
The central nervous system (CNS) and the peripheral nervous system.
53
What does the central nervous system (CNS) consist of?
The brain and the spinal cord.
54
What does the peripheral nervous system consist of?
Nerve cells that transmit information to and from the CNS.
55
Where is the cardiac control centre located?
In the medulla oblongata of the brain.
56
What happens to sympathetic and parasympathetic nerve impulses when heart rate increases?
Sympathetic impulses are sent to the SAN, and there is a decrease in parasympathetic impulses.
57
What stimulates the cardiac control centre?
Chemoreceptors, baroreceptors, and proprioceptors.
58
What is the medulla oblongata?
The most important part of the brain as it regulates processes that keep us alive such as breathing and heart rate.
59
What are chemoreceptors?
Chemoreceptors are sensory receptors found in the carotid arteries and the aortic arch that sense chemical changes.
60
What are the cartoid arteries?
Major blood vessels on either side of the neck that supply blood to the head, face, and brain.
61
What is the aortic arch?
a curved section of the aorta, the largest artery in the body, located in the chest.
62
What do chemoreceptors detect during exercise?
During exercise, chemoreceptors detect an increase in carbon dioxide.
63
How does blood carbon dioxide affect heart rate?
An increased concentration of carbon dioxide in the blood stimulates the sympathetic nervous system, causing the heart to beat faster.
64
What are baroreceptors?
Baroreceptors contain nerve endings that respond to the stretching of the arterial wall caused by changes in blood pressure.
65
What is the function of baroreceptors?
Baroreceptors establish a set point for blood pressure.
66
What happens when blood pressure increases above the set point?
Baroreceptors send signals to the medulla in the brain, resulting in a decrease in heart rate.
67
What happens when blood pressure decreases below the set point?
Baroreceptors send signals to the medulla in the brain, resulting in an increase in heart rate.
68
How does exercise affect the baroreceptor set point?
At the start of exercise, the baroreceptor set point increases.
69
Why is the increase in baroreceptor set point important during exercise?
It prevents heart rate from slowing down, ensuring adequate oxygen delivery to working muscles.
70
What are proprioceptors?
Proprioceptors are sensory nerve endings located in muscles, tendons, and joints that provide information about movement and body position.
71
What do proprioceptors detect at the start of exercise?
They detect an increase in muscle movement.
72
What happens after proprioceptors detect increased muscle movement?
They send an impulse to the medulla, which then sends an impulse through the sympathetic nervous system to the SAN to increase heart rate.
73
What effect does the parasympathetic system have on heart rate?
When the parasympathetic system stimulates the SAN, heart rate decreases.
74
What do chemoreceptors do?
Increase in CO leads to an increase in heart rate.
75
What do baroreceptors do?
Increase in blood pressure leads to a decrease in heart rate.
76
What do proprioceptors do?
Increase in muscle movement leads to an increase in heart rate.
77
What is hormonal control mechanism?
Hormonal control mechanism refers to the effect hormones have on heart rate.
78
What hormone is released during exercise that affects heart rate?
Adrenaline is the hormone released during exercise that affects heart rate.
79
What is the role of adrenaline during exercise?
Adrenaline stimulates the SAN (pacemaker), increasing the speed and force of contraction.
80
What is the result of increased adrenaline during exercise?
Increased adrenaline results in higher cardiac output, pumping more blood to working muscles.
81
Why is more blood pumped to working muscles during exercise?
More blood is pumped to provide working muscles with the oxygen they need for energy.
82
What happens to the heart during exercise?
The heart has to work harder to transport more oxygen to the working muscles.
83
What changes occur in the body during exercise?
More blood is pumped around the body and at a faster rate.
84
What measurements change as a result of exercise?
Stroke volume, heart rate, and cardiac output all change.
85
What is stroke volume?
Stroke volume is the volume of blood pumped out by the heart ventricles in each contraction. On average, the resting stroke volume is approximately 70ml.
86
What does stroke volume depend upon?
Stroke volume depends upon venous return and the elasticity of cardiac fibres.
87
What is venous return?
Venous return is the volume of blood returning to the heart via the veins. If venous return increases, then stroke volume will also increase.
## Footnote
If more blood enters the heart, then more blood goes out!
88
What is the elasticity of cardiac fibres?
The elasticity of cardiac fibres is concerned with the degree of stretch of cardiac tissue during the diastole phase of the cardiac cycle. The more the cardiac fibres can stretch, the greater the force of contraction will be.
89
What is Starlings Law?
Starlings Law states that a greater force of contraction can increase the ejection fraction.
90
What is the Diastole phase?
When the heart relaxes to fill with blood.
91
What is ejection fraction?
The percentage of blood pumped out by the left ventricle per beat.
92
What is Starling's Law?
Increased venous return leads to greater diastolic filling of the heart.
93
What happens to cardiac muscle according to Starling's Law?
Cardiac muscle is stretched.
94
What is the result of the stretching of cardiac muscle?
It leads to a more forceful contraction.
95
What is the final outcome of Starling's Law?
Increased ejection fraction.
96
What is the relationship between contractility of cardiac tissue and force of contraction?
The greater the contractility of cardiac tissue, the greater the force of contraction.
97
What is the effect of increased contractility on stroke volume?
Increased contractility results in an increase in stroke volume.
98
What does ejection fraction refer to?
Ejection fraction refers to the percentage of blood pumped out by the left ventricle per beat.
99
What is the average ejection fraction value?
The average ejection fraction value is 60 percent.
100
How much can ejection fraction increase following a period of training?
Ejection fraction can increase by up to 85 percent following a period of training.
101
What is the equation for ejection fraction?
Amount of blood pumped out of the ventricle
/
Total amount of blood in ventricle
102
What is heart rate?
This is the number of times the heart beats per minute.
103
What is the average resting heart rate?
On average, the resting heart rate is approximately 72 beats per minute.
104
What is cardiac output?
Cardiac output is the volume of blood pumped out by the heart ventricles per minute.
105
How is cardiac output calculated?
Cardiac output (Q) = Stroke volume (SV) x Heart rate (HR)
106
What is the formula for cardiac output?
Q = SV x HR
107
What is the example calculation for cardiac output?
Q = 70 ml x 72 = 5040 ml (5.04 litres)
108
What happens to cardiac output if heart rate or stroke volume increases?
If heart rate or stroke volume increase, then cardiac output will also increase.
109
How does heart rate respond to exercise intensity?
Heart rate increases with exercise intensity; the higher the intensity, the higher the heart rate.
110
How is maximum heart rate calculated?
Maximum heart rate can be calculated by subtracting your age from 220.
111
What is the maximum heart rate of an 18-year-old?
An 18-year-old will have a maximum heart rate of 202 beats per minute.
## Footnote
Calculation: 220 - 18 = 202
112
How does training affect heart rate range?
A trained performer has a greater heart rate range due to a lower resting heart rate and a higher maximum heart rate.
113
What are the resting heart rates of Sir Bradley Wiggins and Mo Farah?
Sir Bradley Wiggins has a resting heart rate of 35 bpm, and Mo Farah has a resting heart rate of 33 bpm.
114
What is the resting heart rate and maximum heart rate of a 40-year-old untrained individual?
A 40-year-old untrained individual has a resting heart rate of 72 bpm and a maximum heart rate of 180 bpm.
## Footnote
Maximum heart rate is linked to age.
115
What types of exercise are illustrated in the graphs?
The graphs illustrate heart rate during maximal exercise such as sprinting and sub-maximal exercise such as jogging.
116
What is anticipatory rise?
Anticipatory rise is a small increase in something (like heart rate, body temperature, or hormones) that happens before an expected event, as the body or brain gets ready for it.
117
What is the result of regular aerobic training on cardiac muscle?
Regular aerobic training will result in more cardiac muscle.
118
What is cardiac hypertrophy?
The thickening of the muscular wall so that it becomes bigger and stronger, also can mean a larger ventricular cavity.
119
How does cardiac hypertrophy affect stroke volume?
A bigger, stronger heart will enable more blood to be pumped out per beat (i.e. stroke volume).
120
What happens to the end diastolic volume of the ventricle with cardiac hypertrophy?
The end diastolic volume of the ventricle increases.
121
What is the effect of a stronger ventricle contraction on heart rate?
If the ventricle can contract with more force, the heart does not have to beat as often, so resting heart rate will decrease.
122
What is bradycardia?
A decrease in resting heart rate below 60bpm
123
How does a lower resting heart rate affect oxygen delivery?
Oxygen delivery to the muscles improves as there is less oxygen needed for contractions of the heart.
124
What happens to cardiac output during exercise?
There is a large increase in cardiac output due to an increase in heart rate and stroke volume.
125
How does cardiac output change with exercise intensity?
Cardiac output increases as exercise intensity increases until maximum intensity is reached, then it plateaus (evens out).
126
Cardiac output in a trained and untrained individual, both at rest and during exercise.
127
Cardiac output response to exercise graph
128
How is maximum heart rate calculated?
Maximum heart rate is calculated as 220 minus your age.
129
What remains the same at rest for both trained and untrained performers?
At rest, cardiac output for both the trained and untrained performer stays the same.
130
What changes during exercise for trained performers?
It is maximum cardiac output that changes, allowing trained performers to transport more blood and oxygen to working muscles.
131
How does blood flow distribution change during exercise?
A much higher proportion of blood passes to the working muscles and less passes to organs such as the intestine.
132
What happens to blood flow to the kidneys and brain during exercise?
The amount of blood passing to the kidneys and brain remains unaltered.
133
What happens to stroke volume as exercise intensity increases?
Stroke volume increases as exercise intensity increases up to 40-60 percent of maximum effort.
134
What occurs to stroke volume after reaching 40-60 percent of maximum effort?
Stroke volume plateaus after reaching 40-60 percent of maximum effort.
135
Why does stroke volume plateau at high exercise intensities?
The increased heart rate near maximum effort results in a shorter diastolic phase, reducing the time for ventricles to fill with blood.
136
What is a diastolic phase?
The period in the cardiac cycle when the heart chambers are relaxed and filling with blood.
137
What is heart disease commonly referred to as?
Heart disease is more commonly referred to as coronary heart disease or CHD.
138
What is the leading cause of deaths in the UK and around the world?
Coronary heart disease (CHD) is the leading cause of deaths both in the UK and around the world.
139
What happens to the coronary arteries in coronary heart disease?
Coronary heart disease occurs when the coronary arteries become blocked or start to narrow due to a gradual build-up of fatty deposits.
140
What is the process called when fatty deposits build up in the arteries?
The process is called atherosclerosis.
141
What does atherosclerosis occur?
When arteries harden and narrow as they become clogged up by fatty deposits.
142
What are the fatty deposits in atherosclerosis called?
The fatty deposits are called atheroma.
143
What is atheroma?
A fatty deposit found in the inner lining of an artery
144
What factors can cause atherosclerosis?
High blood pressure, high levels of cholesterol, lack of exercise, and smoking can all cause atherosclerosis.
145
What occurs when the coronary arteries become narrow?
When the coronary arteries become narrow, they are unable to deliver enough oxygen to the heart, leading to pain and discomfort.
146
What is the pain and discomfort caused by reduced oxygen supply to the heart called?
This pain and discomfort is called angina.
147
What is angina?
Chest pain that occurs when the blood supply through the coronary arteries to the muscles of the heart is restricted.
148
What can happen if a piece of atheroma breaks off in the coronary artery?
If a piece of atheroma breaks off, it can cause a blood clot, resulting in a blockage that cuts off the supply of oxygenated blood to the heart muscle, leading to a heart attack.
149
How does regular exercise benefit the heart?
Regular exercise keeps the heart healthy and more efficient, allowing it to pump more blood around the body.
150
What effect does exercise have on the heart muscle?
Exercise makes the heart bigger and stronger, resulting in an increase in stroke volume.
151
What additional benefits does regular exercise provide for blood vessels?
Regular exercise maintains the flexibility of blood vessels, ensuring good blood flow, normal blood pressure, and low cholesterol levels.
152
How much exercise does the American Heart Association recommend per week?
The American Heart Association recommends at least 150 minutes per week of moderate exercise, like brisk walking.
153
What is blood pressure?
High blood pressure is the force exerted by the blood against the blood vessel wall.
154
What does high blood pressure come from?
High blood pressure comes from the heart as it pumps blood around the body.
155
What are the risks of untreated high blood pressure?
Untreated high blood pressure increases the risk of heart attack, heart failure, kidney disease, stroke, or dementia.
156
How can regular aerobic exercise affect blood pressure?
Regular aerobic exercise can reduce blood pressure by lowering both systolic and diastolic pressure by up to 5-10 mmHg.
157
What is the potential reduction in heart attack risk from lowering blood pressure through exercise?
Lowering blood pressure can reduce the risk of a heart attack by up to 20 percent.
158
What are the two types of cholesterol?
LDL (low density lipoproteins) and HDL (high density lipoproteins).
159
What is LDL cholesterol known for?
LDL transports cholesterol in the blood to the tissues and is classed as 'bad' cholesterol since it is linked to an increased risk of heart disease.
160
What is HDL cholesterol known for?
HDL transports excess cholesterol in the blood back to the liver where it is broken down. It is classed as 'good' cholesterol since it lowers the risk of developing heart disease.
161
How does regular physical activity affect cholesterol levels?
Regular physical activity lowers bad LDL cholesterol levels and significantly increases good HDL cholesterol levels.
162
What does the brain need to maintain its function?
The brain needs a constant supply of oxygenated blood and nutrients.
163
What is a stroke?
A stroke occurs when the blood supply to part of the brain is cut off, causing damage to brain cells.
164
What can a stroke lead to?
A stroke can lead to brain injury, disability, and sometimes death.
165
What are the two main types of stroke?
The two main types of stroke are Ischaemic strokes and Haemorrhagic strokes.
166
What causes Ischaemic strokes?
Ischaemic strokes occur when a blood clot stops the blood supply.
167
What causes Haemorrhagic strokes?
Haemorrhagic strokes occur when a weakened blood vessel supplying the brain bursts.
168
How can regular exercise affect stroke risk?
Regular exercise can help lower blood pressure and maintain a healthy weight, reducing stroke risk by 27 percent.
169
What is a steady state?
Where the athlete is able to meet the oxygen demand with the oxygen supply
170
What is cardiovascular drift?
Cardiovascular drift is characterised by a progressive decrease in stroke volume and arterial blood pressure, together with a progressive rise in heart rate.
171
When does cardiovascular drift occur?
It occurs during prolonged exercise (after 10 minutes) in a warm environment, despite the intensity of the exercise remaining the same.
172
What causes cardiovascular drift?
When we sweat, a portion of the lost fluid volume comes from the plasma volume, reducing venous return and stroke volume, which causes heart rate to increase to maintain cardiac output.
173
How can cardiovascular drift be minimised?
It is important to maintain high fluid consumption before and during exercise.
174
Cardiovascular drift graph
175
What is the vascular system?
The vascular system is made up of blood vessels that carry blood through the body.
176
What do blood vessels deliver to body tissues?
Blood vessels deliver oxygen and nutrients to the body tissues.
177
What waste products do blood vessels take away?
Blood vessels take away waste products such as carbon dioxide.
178
What organs work together with blood vessels?
The heart and lungs work together with blood vessels.
179
What is the role of blood vessels during exercise?
Blood vessels ensure that muscles have an adequate supply of oxygen during exercise.
180
What are the two types of circulation?
The two types of circulation are pulmonary and systemic.
181
What is pulmonary circulation?
Pulmonary circulation is the movement of deoxygenated blood from the heart to the lungs and oxygenated blood back to the heart.
182
What is systemic circulation?
Systemic circulation is the movement of oxygenated blood to the body from the heart and the return of deoxygenated blood from the body to the heart.
183
184
What is the vascular system?
The vascular system is made up of blood vessels that carry blood through the body.
185
What do blood vessels deliver to body tissues?
Blood vessels deliver oxygen and nutrients to the body tissues.
186
What waste products do blood vessels take away?
Blood vessels take away waste products such as carbon dioxide.
187
What organs work together with blood vessels?
The heart and lungs work together with blood vessels.
188
What is the role of blood vessels during exercise?
Blood vessels ensure that muscles have an adequate supply of oxygen during exercise.
189
What are the two types of circulation?
The two types of circulation are pulmonary and systemic.
190
What is pulmonary circulation?
Pulmonary circulation is the movement of deoxygenated blood from the heart to the lungs and oxygenated blood back to the heart.
191
What is systemic circulation?
Systemic circulation is the movement of oxygenated blood to the body from the heart and the return of deoxygenated blood from the body to the heart.
192
What are the components of the vascular system?
The vascular system consists of five different blood vessels: Heart, Arteries, Arterioles, Capillaries, Venules, and Veins.
193
What are arterioles?
Very small blood vessels that branches off from your artery and carries blood away from your heart to your tissues and organs.
194
What are venules?
Tiny blood vessels that serve as the connection between capillaries and veins.
195
What is the flow of blood through the vascular system?
Blood flows from the Heart to Arteries, then to Arterioles, Capillaries, Venules, and back to the Veins and Heart.
196
How do veins differ from arteries?
Veins have thinner muscle/elastic tissue layers, a wider lumen, and valves, while arteries have a thicker elastic outer layer, a smaller lumen, and carry blood at high pressure.
197
What is unique about capillaries?
Capillaries are only wide enough to allow one red blood cell to pass through at a time, which slows down blood flow and allows nutrient exchange by diffusion.
198
What is blood pressure?
Blood pressure is the force exerted by the blood against the blood vessel wall and is often referred to as: blood flow x resistance.
199
What happens to blood pressure during exercise?
During exercise, blood pressure increases to enhance blood flow through the circulatory system, ensuring muscles receive the necessary oxygen.
200
What is systolic pressure?
Systolic pressure is the pressure of contraction when the heart forces blood out under high pressure.
201
What is diastolic pressure?
Diastolic pressure is the lower pressure in the arteries as the ventricles relax.
202
How is blood pressure measured?
Blood pressure is measured at the brachial artery in the upper arm.
203
What is a typical resting blood pressure reading?
A typical resting blood pressure reading is 120 mmHg/80 mmHg.
204
How does blood pressure vary in different blood vessels?
Blood pressure varies in different blood vessels and is largely dependent on the distance from the heart.
205
What is the pressure in veins?
The pressure of blood in the veins is low, which necessitates mechanisms to pump the blood back to the heart.
206
What happens to venous return during exercise?
During exercise, the amount of blood returning to the heart increases.
207
What is venous return?
Venous return is the return of blood to the right side of the heart via the vena cava.
208
What percentage of total blood volume is contained in the veins at rest?
Up to 70 percent of the total volume of blood is contained in the veins at rest.
209
What happens to venous return during exercise?
During exercise, the amount of blood returning to the heart (venous return) increases.
210
What is the relationship between venous return and stroke volume?
If more blood is being pumped back to the heart, then more blood has to be pumped out, so stroke volume will increase.
211
What is Starling's Law?
Starling's Law states that an increase in venous return leads to an increase in stroke volume.
212
What is the pressure of blood in the large veins?
The pressure of the blood in the large veins is very low, making it difficult to return blood to the heart.
213
What is the role of the large lumen of the vein?
The large lumen of the vein offers little resistance to blood flow.
214
What mechanisms assist venous return?
Active mechanisms are needed to help venous return.
215
What is the skeletal muscle pump?
When muscles contract and relax, they change shape, pressing on nearby veins and causing a pumping effect to squeeze blood towards the heart.
216
What is the respiratory pump?
During breathing, pressure changes in the thoracic and abdominal cavities compress nearby veins and assist blood return to the heart.
217
What are pocket valves?
Pocket valves ensure that blood in the veins flows in one direction by closing after blood passes through them to prevent backflow.
218
What aids venous return in addition to pumps?
A thin layer of smooth muscle in the walls of the veins helps squeeze blood back towards the heart.
219
How does gravity assist venous return?
Gravity helps the blood return to the heart from the upper body.
220
What is the suction pump action of the heart?
The suction pump action of the heart aids in returning blood to the heart.
221
Why is it important to maintain venous return during exercise?
To ensure the skeletal muscles are receiving enough oxygen to meet the demands of the activity.
222
What mechanisms are sufficient to maintain venous return at rest?
Valves and the smooth muscle found in veins.
223
What changes occur in the vascular system during exercise?
The demand for oxygen increases and the heart beats faster, necessitating additional support for venous return.
224
What are the two pumps needed to maintain venous return during exercise?
The skeletal muscle pump and the respiratory pump.
225
How do the skeletal muscle pump and respiratory pump function during exercise?
Skeletal muscles are constantly contracting and breathing is elevated.
226
What should be done immediately after exercise to maintain venous return?
Performing an active cool-down.
227
What is the benefit of an active cool-down?
It keeps the skeletal muscle pump and respiratory pump working, preventing blood pooling (blood collecting in the veins).
228
What is systolic pressure?
Systolic pressure is the pressure in the blood vessels when the ventricles are contracting.
229
What is diastolic pressure?
Diastolic pressure is the pressure in the blood vessels when the ventricles are relaxing.
230
How does an increase in systolic blood pressure affect venous return?
An increase in systolic blood pressure leads to an increase in venous return.
231
How does a decrease in systolic blood pressure affect venous return?
A decrease in systolic blood pressure leads to a decrease in venous return.
232
What is venous return (VR)?
Venous return (VR) is the flow of blood back to the heart in the veins.
233
How does venous return relate to stroke volume?
Under normal circumstances, venous return is the same as stroke volume (i.e. what goes in comes out).
234
What does Starling's Law state?
Starling's Law states that if venous return increases, the heart contracts with more force, increasing the ejection fraction and stroke volume.
235
What determines venous return?
Venous return is determined by a pressure gradient.
236
How is the pressure gradient calculated?
The pressure gradient is the mean systemic pressure minus the right atrial pressure.
237
What is resistance in the context of venous return?
Resistance is the total peripheral vascular resistance.
238
What leads to an increase in venous return?
An increase in venous pressure (PV), a decrease in right atrial pressure (PRA), or a decrease in venous resistance (RV) leads to an increase in venous return.
239
What effect does increasing right atrial pressure have on venous return?
Increasing right atrial pressure decreases venous return.
240
What is the typical blood pressure in the right atrium and peripheral veins?
The blood pressure in both the right atrium (PRA) and the peripheral veins (PV) is normally very low.
241
How do small changes in blood pressure affect venous return?
Small changes in blood pressure in either the right atrium or the peripheral veins can cause a large change in the pressure gradient, significantly affecting the return of blood to the right atrium.
242
What happens during inspiration regarding venous return?
During inspiration, small changes in blood pressure between the atria and the abdominal cavity cause a large increase in the pressure gradient driving venous return from the peripheral circulation to the right atrium.
243
What is inspiration?
The process of breathing in (inhalation).
244
What role does oxygen play in the body?
Oxygen plays a major role in energy production and a reduction in the amount of oxygen in the body will have a detrimental impact on performance.
245
What happens to oxygen during exercise?
During exercise, 3 per cent of oxygen dissolves into plasma and 97 per cent combines with haemoglobin to form oxyhaemoglobin.
246
How many oxygen molecules can fully saturated haemoglobin carry?
When fully saturated, haemoglobin will carry four oxygen molecules.
247
When does haemoglobin become fully saturated?
This occurs when the partial pressure of oxygen in the blood is high, for example in the alveolar capillaries of the lungs.
248
What is partial pressure?
Partial pressure is the pressure that a single gas in a mixture of gases would exert if it occupied the entire volume by itself at the same temperature.
249
What is oxyhaemoglobin dissociation?
The release of oxygen from oxyhaemoglobin to the tissues is referred to as oxyhaemoglobin dissociation.
250
How is oxygen stored in the muscle?
In the muscle, oxygen is stored by myoglobin, which has a higher affinity for oxygen.
251
What is the function of myoglobin?
Myoglobin stores oxygen for the mitochondria until it is used by the muscles.
252
Where does aerobic respiration take place in the muscle?
The mitochondria are the centres in the muscle where aerobic respiration takes place.
253
What is plasma?
The fluid part of blood (mainly water) that surrounds blood cells and transports them.
254
What is haemoglobin?
An iron-containing pigment found in red blood cells, which combines with oxygen to form oxyhaemoglobin.
255
What is myoglobin?
Often called ‘muscle haemoglobin’. It is an iron-containing muscle pigment in slow-twitch muscle fibres which has a higher affinity for oxygen in the muscle fibres which can be used quickly when exercise begins.
256
What is mitochondria?
Often referred to as the powerhouse of the cell as respiration and energy production occur there.
257
What does the oxyhaemoglobin dissociation curve represent?
The curve represents the relationship between oxygen and haemoglobin.
258
What does the oxyhaemoglobin dissociation curve help us understand?
It helps us to understand how haemoglobin in our blood transports and releases oxygen.
259
The oxyhaemoglobin dissociation curve
260
What is the saturation level of haemoglobin at the partial pressure of oxygen in the lungs?
Haemoglobin is almost completely saturated with oxygen.
261
What happens to haemoglobin in the tissues?
In the tissues, the partial pressure of oxygen is lower, therefore, haemoglobin gives up some of its oxygen to the tissues.
262
What happens to haemoglobin in the lungs?
Haemoglobin is saturated with oxygen, making it virtually full.
263
What occurs to haemoglobin at the tissues?
Haemoglobin releases some oxygen, causing it to become partially empty.
264
What percentage of oxygen does haemoglobin give up to the muscles?
Haemoglobin gives up 23 percent of its oxygen to the muscles.
265
How does the oxygen release from haemoglobin change during exercise?
A bigger percentage of oxygen is released from haemoglobin during exercise.
266
Why is the oxygen release from haemoglobin sufficient at rest?
The demand for oxygen by the muscles is not high at rest.
267
The effect of changing acidity on the oxyhaemoglobin dissociation curve.
268
What happens to the S-shaped curve during exercise?
The S-shaped curve shifts to the right because muscles require more oxygen, leading to easier dissociation of oxygen from haemoglobin in the blood capillaries to the muscle tissue.
## Footnote
This shift to the right is known as the Bohr shift.
269
What are the three factors that increase the dissociation of oxygen from haemoglobin during exercise?
1. Increase in blood temperature
2. Increase in partial pressure of carbon dioxide
3. Decrease in pH
## Footnote
These factors result in more oxygen being available for use by the working muscles.
270
How does an increase in blood temperature affect oxygen dissociation?
When blood and muscle temperature increases during exercise, oxygen will dissociate from haemoglobin more readily.
271
What effect does an increase in partial pressure of carbon dioxide have on oxygen dissociation?
As the level of blood carbon dioxide rises during exercise, oxygen will dissociate faster from haemoglobin.
272
How does pH affect oxygen dissociation from haemoglobin?
More carbon dioxide lowers the pH in the blood. A drop in blood pH will cause oxygen to dissociate from haemoglobin more quickly.
273
How does blood flow distribution differ at rest compared to during exercise?
During exercise, blood flow is redirected to skeletal muscles to meet increased oxygen demand.
274
What is the term for the redirecting of blood flow to areas of high demand?
This process is known as shunting or the vascular shunt mechanism.
275
What is the vascular shunt mechanism?
The redistribution of cardiac output.
276
The Vascular Shunt figure
277
Why should sports performers avoid eating less than an hour before competition?
Eating too close to competition can redirect blood flow to the stomach instead of the working muscles, negatively impacting performance.
278
What happens to blood flow when the stomach is full?
More blood is directed to the stomach, resulting in less oxygen available for the working muscles.
279
Why is constant blood flow to the brain important?
The brain requires oxygen for energy, and constant blood flow ensures brain function is maintained.
280
What does the heart need for energy during physical activity?
The heart muscle needs oxygen to beat faster, which requires increased blood flow.
281
Why does more blood flow to the skin during exercise?
Increased blood flow to the skin is necessary to cool the body down.
282
What controls blood pressure and blood flow?
The vasomotor centre, located in the medulla oblongata of the brain.
283
What chemical changes are detected by chemoreceptors during exercise?
Increases in carbon dioxide and lactic acid.
284
What is vasodilation?
Vasodilation is when the blood vessel widens to increase blood flow into the capillaries.
285
What is vasoconstriction?
Vasoconstriction is when the blood vessel narrows to decrease blood flow.
286
What happens to blood flow during exercise in working muscles?
Vasodilation occurs in the arterioles supplying these muscles, increasing blood flow and bringing in oxygen.
287
What happens to blood flow in non-essential organs during exercise?
Vasoconstriction occurs in the arterioles supplying non-essential organs such as the intestines and liver.
288
How do sympathetic nerves affect blood flow?
Increased sympathetic stimulation causes vasoconstriction and reduces blood flow, while decreased stimulation causes vasodilation and increases blood flow.
289
What are pre-capillary sphincters?
Tiny rings of muscle located at the opening of capillaries that regulate blood flow.
290
What happens to pre-capillary sphincters during exercise?
They relax to increase blood flow to the capillary networks supplying skeletal muscle.
291
Why is redistribution of blood important during exercise?
To increase oxygen supply to working muscles, remove waste products, regulate body temperature, and direct blood to the heart.
292
What is arterio-venous difference (A-VO, diff)?
It is the difference between the oxygen content of the arterial blood arriving at the muscles and the venous blood leaving the muscles.
293
How does the arterio-venous difference change at rest?
At rest, the arterio-venous difference is low as not much oxygen is required by the muscles.
294
How does the arterio-venous difference change during exercise?
During exercise, the arterio-venous difference is high as much more oxygen is needed from the blood for the muscles.
295
What effect does an increased arterio-venous difference have on gaseous exchange?
It affects gaseous exchange at the alveoli, resulting in more oxygen being taken in and more carbon dioxide being removed.
296
How does training affect the arterio-venous difference?
Training increases the arterio-venous difference as trained performers can extract a greater amount of oxygen from the blood.
297
What does the body need to produce energy?
The body needs a continuous supply of oxygen to produce energy.
298
What waste product is produced when oxygen is used to break down food?
Carbon dioxide is produced as a waste product.
299
What is respiration?
Respiration is the taking in of oxygen and the removal of carbon dioxide.
300
What are the components of respiration?
Respiration includes ventilation, external respiration, transport of gases, internal respiration, and cellular respiration.
301
What is ventilation?
Ventilation is getting air into and out of the lungs.
302
What is external respiration?
External respiration is the gaseous exchange between the lungs and blood.
303
What does the transport of gases refer to?
The transport of gases refers to the movement of oxygen and carbon dioxide in the bloodstream.
304
What is internal respiration?
Internal respiration is the exchange of gases between the blood in the capillaries and the body cells.
305
What is cellular respiration?
Cellular respiration is the metabolic reactions and processes that take place in a cell to obtain energy from fuels such as glucose.
306
What is air composed of?
Air is a mixture of gases.
307
How does air enter the body?
Air is drawn into the body through the nose.
308
What is the pathway of air after entering the nose?
It passes through the pharynx and onto the larynx (voice box).
309
What is the next structure air travels through after the larynx?
Air travels down the trachea (windpipe).
310
What are the two main branches that air enters after the trachea?
Air enters the right and left bronchus.
311
What happens to the bronchi as air moves through them?
They subdivide into secondary bronchi.
312
What is the progression of the bronchi after the secondary bronchi?
They get progressively thinner and branch into bronchioles.
313
What do bronchioles lead into?
Bronchioles lead into respiratory bronchioles.
314
What is the final destination of air in the respiratory system?
The final destination is the alveoli.
315
Structure of the respiratory system figure.
316
What does nearly lobbed the ball brilliantly again stand for?
Nose, larynx, trachea, bronchi, bronchioles, alveoli.
317
What are the alveoli responsible for?
The alveoli are responsible for the exchange of gases between the lungs and the blood.
318
How does gas exchange occur in the alveoli?
Gas exchange occurs via diffusion, which is the movement of gas molecules from an area of high partial pressure to an area of low partial pressure.
319
What is the structure of alveoli designed for?
The structure of alveoli is designed to help gaseous exchange.
320
How thick are the walls of the alveoli?
The walls of the alveoli are very thin, only one cell thick.
321
Why is there a short diffusion pathway in the alveoli?
There is a short diffusion pathway because there are only two layers of cells from the air in the alveoli to the blood.
322
What surrounds the alveoli and why is it important?
An extensive capillary network surrounds the alveoli, providing an excellent blood supply.
323
Why do alveoli have a huge surface area?
Alveoli have a huge surface area because there are millions of alveoli in each lung, allowing for greater uptake of oxygen.
324
What is diffusion?
The movement of gas molecules from an area of high concentration or partial pressure to an area of low concentration or partial pressure.
325
What is gaseous exchange?
The movement of oxygen from the air into the blood, and carbon dioxide from the blood into the air.
326
What is the principle behind air movement during breathing?
Air moves from an area of high pressure to an area of low pressure via diffusion.
327
What is required for inspiration?
The pressure in the lungs needs to be lower than in the atmosphere.
328
What is required for expiration?
The pressure in the lungs needs to be higher than in the atmosphere.
329
How does the volume of the thoracic cavity affect lung pressure?
Increasing the volume reduces lung pressure, while decreasing the volume increases lung pressure.
330
What causes pressure changes in the lungs?
The contraction of muscles causes these pressure changes.
331
What muscles are used in breathing at rest during inspiration?
Diaphragm
External intercostals
332
What muscles are used in breathing at rest during inspiration?
Diaphragm
External intercostals
Sternocleidomastoid
Scalenes
Pectoralis minor
333
What muscles are used in breathing at rest during expiration?
Passive: diaphragm and external intercostals just relax
334
What muscles are used in breathing at rest during expiration?
Internal intercostals
Abdominals
335
The mechanics of inhaling figure
336
The mechanics of exhaling figure
337
What is the movement of air into and out of the lungs called?
The movement of air into and out of the lungs is called respiration.
338
What is inspiration?
Inspiration is taking air into the lungs.
339
What is expiration?
Expiration is moving air out of the lungs.
340
What is the approximate tidal volume at rest?
At rest, we inspire and expire approximately 0.5 litres of air.
341
What is tidal volume?
Tidal volume is the volume of air inspired or expired per breath.
342
What is minute ventilation?
Minute ventilation is the volume of air inspired or expired per minute.
343
How is minute ventilation calculated?
Minute ventilation can be calculated by multiplying the number of breaths taken per minute by the tidal volume.
## Footnote
Example: 12 breaths/min × 0.5 litres = 6 litres/min.
344
What is inspiratory reserve volume (IRV)?
Inspiratory reserve volume (IRV) is the extra amount of air inspired beyond the tidal volume.
345
What is expiratory reserve volume (ERV)?
Expiratory reserve volume (ERV) is the extra amount of air expired beyond the tidal volume.
346
How does exercise affect lung volumes?
Exercise increases the depth of breathing, leading to an increase in tidal volume.
