Chapter 1- Applied Antomy and Physiology (Paper 1) Flashcards
Define myongenic
The capacity of the heart to generate its own impulses.
Define sinoatrial node (SAN or SA node)
A small mass of cardiac muscle found in the wall of the right atrium that generates the heartbeat.
Define atrioventricular node (AVN or AV node)
The node relays the impulse between the upper and lower sections of the heart.
Define systole
When the heart contracts
Define bundle of hiss
A collection of heart muscle cells that transmit electrical impulses from the AVN via the bundle branches to the ventricles.
Define purkinje fibres
Muscle fibres that conduct impulses in the walls of ventricles.
Define stroke volume
The volume of blood pumped out by the heart ventricles in each contraction.
Define cardiac output
The volume of blood pumped out the heart ventricles per minute.
What is a sympathetic system?
A part of the autonomic nervous system that speeds up heart rate.
What is a parasympathetic system?
A part of the autonomic system that decreases heart rate.
What is medulla oblongata?
The most important part of the brain as it regulates processes that keep us alive such as breathing and heart rate.
What are chemoreceptors?
Tiny structures in the carotid arteries and aortic arch that detect changes in blood acidity caused by an increase or decrease in the concentration of carbon dioxide.
What are baroreceptors?
Special sensors in tissues the aortic arch, carotid sinus, heart and pulmonary vessels that respond to changes in blood pressure to either increase or decrease heart rate.
What is adrenaline?
A stress hormone that is released by the sympathetic nerves and cardiac nerve during exercise which causes an increase in heart rate.
What is the ejection fraction?
The percentage of blood pumped out by the left ventricle per beat.
What are proprioceptors?
Sensory nerve endings in the muscle, tendons and joints that detect changes in muscle movements.
What is cardiac hypertrophy?
The thickening of the muscular wall of the heart so it becomes bigger and stronger; also can mean a larger ventricular cavity.
What is bradycardia?
A decrease in resting heart rate below 60 beats per minute.
What is atherosclerosis?
Occurs when arteries harden and narrow as they become clogged up by fatty deposits.
What is atheroma?
A fatty deposit found in the inner lining of an artery.
What is agina?
Chest pain that occurs when the blood supply through the coronary arteries to the muscles of the heart is restricted.
What is a stroke?
A stroke occurs when the blood supply to the brain is cut off.
Name the four chambers of the heart.
Right atrium
Left atrium
Right ventricle
Left ventricle
Which chambers of the heart are larger explain why?
The ventricles have larger muscles and are thicker because they need to be stronger to be able to pump the blood all around the body whereas the atria just have to contract and let the blood into the ventricles below.
Which side of the heart is larger? Explain how
The left side is larger as it sends blood all around the body but the right side only pumps it to the blood to the lungs behind.
Name the main blood vessels that enter and leave the heart.
- vena cava inferior and superior
- pulmonary artery
- pulmonary vein
- aorta
What are the names of the valves in the heart and where are they located?
In the right and left side of of the heart there are atrioventricular valves. The right has a tricuspid valve whereas the left has a bicuspid valve. There are also semilunar valves located at the connection between the the pulmonary artery and the right ventricle and the connection between the aorta and the left ventricle.
What is the main function of the valves?
They regulate blood flow in the heart ensuring that it flows in only one direction. They open to allow blood through and then close to prevent back flow.
What is the formula for cardiac output?
Q=SV x HR
Describe the cardiac cycle.
1) (Atrial diastole) Atria fill with blood while the atrioventricular valves are closed.
2) The atrioventricular valves are pushed open by rising blood pressure and the ventricles start to fill with blood. During this time the semilunar valves are closed.
3) The atrial contract forcing remaining blood down into the ventricles.
4) The ventricles contract and atrioventricular valves close. Ventricular contraction forces open semi lunar valves, so that blood is ejected into pulmonary artery and aorta.
What is the cardiac cycle?
The cardiac cycle is a sequence of events that make up one heart beat
How long does the cardiac cycle last?
0.8 seconds on average
How long is the diastole period?
0.5 seconds
How long is the systole period?
0.3 seconds
What is the septum?
Muscle that separates the two sections of the heart.
Which direction does blood flow in the arteries?
Away from the heart
Which direction does the blood flow in the veins?
Towards the heart
What side of the heart has the deoxygenated blood?
The right side
What side of the heart has the oxygenated blood?
The left side
Describe how the blood flows around the heart?
Blood enters through the vena cava (superior or inferior) and then travels into the right atrium and through the tricuspid valve into the right ventricle. This goes to the lungs. Blood enters through the pulmonary vein then travels into the left atrium through the bicuspid valve. This blood is oxygenated and travels to different parts of the body.
What effect does training have on testing cardiac output and stroke volume?
At rest cardiac output remains the same. The stroke volume however will have increased due to cardiac hypertrophy.
What is venous return?
Return of blood to the right side of the heart via the vena cava.
What happens to the heart rate during exercise?
It increases
What happens to stroke volume during exercise?
It increases. For example resting stroke volume is about 70ml while during exercise it is about 100ml.
What happens to cardiac output during exercise?
It increases because of stroke volume and heart rate increase the cardiac output therefore increases.
What happens to venous return during exercise?
It increases
Describe the hearts conduction cycle.
1) Sinoatrial node (SAN) creates an electrical impulse.
2) This creates atrial systole
3) Electrical impulse reaches the atrioventricular node (AVN). It holds the impulse for 0.1 to 0.2 seconds.
4) Electrical impulse is then sent down the bundle his (in the septum) which branches out to the bundle branches.
5) Electrical impulse reaches the purkinje fibres
6) This causes ventricular systole.
Define diastole?
Relaxation of the heart
What percentage of oxygenated blood goes to the muscles during exercise?
80%
What are the two extrinsic factors that determine the when the heart rate beats?
Neural control
Hormonal control
What is the intrinsic factor that determine the when the heart rate beats?
Intrinsic control
Which of the factors regarding the time when the heart rate beats is most important?
Neural control
Discuss neural control of the heart
The sino-atrial node is stimulated by the sympathetic cardiac accelerator nerve (cardiac nerve) which increases heart rate. The parasympathetic vagus nerve helps slow it down (cardio inhibitor).
Where is the cardiac control centre (CCC)?
In the medulla of the brain
What is the cardiac centre stimulated by?
1) Muscle receptors that respond to movement in the muscles and joints at the onset of exercise. Also known as mechanoreceptors.
2) Chemoreceptors in the muscles that respond to changes in muscle chemistry e.g. A rise in lactic acid
3) Emotional excitement
4) Changes in blood pressure, detected by baroreceptors in the aorta, vena cava, carotid arteries
5) Chemoreceptors in the aorta and carotid arteries that respond to changes in oxygen, carbon dioxide and pH levels
How do the sympathetic and parasympathetic nervous systems work together?
By working antagonistically
Discuss hormonal control of the heart.
Noradrenaline is released that causes an increase in the rate of electrical impulses which therefore increases the heart rate.
Adrenaline, a hormone released when we are stressed, causes an increase in the strength of ventricular contractions.
Acytlcholine lowers the heart rate by slowing down the electrical impulses.
Discuss intrinsic control of the heart.
Our heart warms up when we exercise which makes blood less viscous. (When warm our heart increases, when cold our heart rate decreases) when our heart gets warmer, conduction of nerve impulses speeds up. Venous return increases which stresses the cardiac muscle and stimulates the sinoatrial node which increases heart rate. And overall with increase in stroke volume, cardiac output increases.
What happens when we stop exercising?
Muscle receptors stop stimulating the cardiac control centre and the heart rate begins to fall rapidly. The activity of the chemoreceptors also reduces this, combined with reduced levels of adrenaline, a drop in venous return and a drop in body temperature.
So how does a healthy heart contribute to improved performance?
Aerobic training results in hypertrophy of the cardiac muscle. (Athletes heart). A bigger heart enables more blood to be pumped per beat. As a result the heart does not need to beat as frequently and therefore the resting pulse is lower(bradycardia). Overall cardiac output during exercise is higher.
Discuss cardiovascular drift?
An abnormally high heart rate. When we exercise in hot conditions, we often experience an increase in heart rate. This is because of a drop in blood volume due to an increase in the sweating response. Blood becomes more viscous. This causes venous return return and stroke volume to decrease and heart rate therefore increases.
How do you calculated Maximum heart rate?
220 - age
Define cardiovascular drift.
Refers to the increase in the heart rate that occurs during prolonged endurance exercise with little or no change in workload.
What is the order in the vascular system?
Heart Arteries Arterioles Capillaries Venules Veins Heart
What are the two types of circulation of blood?
Pulmonary and systemic
What is the pulmonary blood transportation?
Deoxygenated blood from the heart to the lungs and oxygenated blood back to the heart.
What is the systemic transportation of blood?
Oxygenated blood to the body from the heart and then return of deoxygenated blood from the body to the heart.
What are the constituents of blood?
- Plasma
- red blood cells
- white blood cells
- Platelets
What is plasma made up of ?
90% water
8% protein
2% salt
What is the function of the red blood cells?
To transport oxygen around the body. Red blood cells contain haemoglobin that pick up oxygen where there is lots and releases oxygen in tissue where the concentration is low.
What is the function of white blood cells?
There main job is to fight disease by killing pathogen that are foreign to our body.
What is the function of platelets?
Platelets are responsible for clotting the blood.
What are platelets?
Tiny fragments of other cells that were formed in the bone marrow.
How many different types of vessels does the vascular system contain?
5 Arteries Arerioles Veins Venules Capillaries
What direction do the arteries and arterioles pump the blood?
They convey blood away from the heart and connect to beds of finely branching capillaries.
What direction do the veins and venules pump the blood around the body?
They transport blood back to the heart.
How many layers does the walls of the arteries and veins have?
3
What are the three layers of wall that the arteries and veins have?
- An inner endothelium (tunica interna)
- A middle layer of smooth muscle and elastic fibres (Tunica medina)
- An outer fibrous layer (Tunica externa)
Which vessel (vein or artery) has thicker muscle and why?
Arteries because the blood pressure in the arteries is higher due to the ventricular contractions.
Does the vein muscle get thicker or thinner towards the heart?
Thicker
Does the diameter of the arteries muscular wall increase or decrease as it gets further away from the heart?
It decreases
What are the properties of arteries? (Name 5)
- Thick muscular walls
- Elastic properties
- Transports blood away from the heart
- Blood transported under high pressure
- Blood squirts and pulsates as a result.
What are the properties of veins? (Name 5)
- Relatively thin muscular walls
- Transport blood back to the heart
- Blood is transported under relatively low pressure
- Blood flow is smooth and slow
- Veins therefore have valves to prevent back flow of blood.
Describe the size of a capillary?
They are very thin and fragile. It is only one epithelial cell thick. They are so thin that blood cells pass through them in single file.
What is the function of the capillaries?
Due to their extremely thin surface the oxygen in red blood cells is able to diffuse into the surrounding tissue and the carbon dioxide can diffuse into the red blood cells.
Where are the semilunar valves?
There is the aortic semilunar valve connected to the aorta and the pulmonary semilunar valve.
Describe the flow of blood through the blood vessels of the heart and state whether the blood is oxygenated and deoxygenated.
- Vena cava brings deoxygenated blood back to the right atrium
- Pulmonary vein delivers oxygenated blood to the left atrium
- The pulmonary artery leaves the right ventricle to the lungs
- Aorta leaves the left ventricle with oxygenated blood leading to the body
Memory tool for chemoreceptors
Increase in co2 -> Increase in heart rate
Memory tool for baroreceptors
Increase in blood pressure -> Decrease in heart rate
Memory tool for propioceptors
Increase in muscle movement -> increase in heart rate
What does stroke volume depend on?
- Venous return (increase = increase)
- The elasticity of the cardiac fibres (greater the cardiac fibres stretch the stronger the contraction will be).
- The contractility of the cardiac tissue (greater force of contractility = greater force of contraction)
Memory tool for starling’s law of the heart
Increase venous return -> Greater diastolic filling of the heart -> Cardiac muscle stretched -> More force of contraction -> increased ejection fraction
What is the ejection fraction calculation?
Stroke volume / end diastolic volume
What is blood pressure?
Blood pressure is the force exerted by the blood against the blood vessel wall.
How do you work out blood pressure?
Blood flow x peripheral resistance
What is systolic pressure?
The pressure in the arteries when the ventricles are contracting.
What is diastolic pressure?
The pressure in the arteries when the ventricles are relaxing.
During exercise what happens to the blood pressure?
The systolic pressure increases.
What is a normal blood pressure?
120 (systolic)/80 (diastolic)mm/Hg (millimetres of mercury)
What is blood pressure dependent on?
Cardiac output and distance of the blood vessel from the heart.
What happens when the blood vessels vasoconstriction regarding blood pressure?
The blood pressure increases.
What happens when the blood flows further away from the heart regarding blood pressure? Why?
The blood pressure decreases because;
- The total cross sectional area of the blood vessels increases with distance from the heart
- Pressure is lost overcoming the friction with the lining of the blood vessels.
There is no pulsing of the blood where and why?
In the capillaries, venules and veins, as the pressure surge caused by the contraction of the left ventricle is spent.
What is used to measure blood pressure?
A Sphygmomanometer
When measuring blood pressure where is the reading taken?
On the brachial artery (bicep area)
During exercise blood pressure changes, what do these changes depend on?
The type and intensity of the exercise being performed.
When does systolic pressure increase and why?
During aerobic activity, due to an increase in cardiac output, while diastolic pressure remains constant.
When does diastolic pressure increase?
During isometric work (muscle both contract working against each other), due to an increased resistance on the blood vessels. This is because during isometric work, the muscles contract causing constant compression on the blood vessels which results in additional resistance to the blood flow in the muscles and therefore an increase in pressure.
What are blood pressure and blood flow controlled by?
The vasomotor centre in the medulla oblongata in the brain.
What is vasomotor control?
Receptors (chemoreceptors and baroreceptors) stimulate the vasomotor centre which redistributes blood flow through vasodilation and vasoconstriction.
What is vasodilation and vasoconstriction and why are they important?
Vasodilation increases blood flow. Vasoconstriction decreases blood flow. In exercise, more oxygen is needed at the working muscles so vasodilation occurs, increasing blood flow and bringing in much needed oxygen. Whereas vasoconstriction will occur in the arterioles supplying non essential organs such as the intestines and liver.
What is the redirection of blood known as?
Shunting or vascular shunt
Why does shunting occur?
There are so many capillaries in the body, that they cannot all be supplied with blood at the same time. There is therefore, competition for blood between different regions of the body, especially during exercise, when blood must be shunted to the working muscles, and consequently withdrawn from other regions.
How is the shunting of blood between competing tissues achieved?
The shunting of blood between competing tissues is achieved by the constriction and dilation of the arterioles entering the capillary beds. Rings of circular muscle in these arterioles act as sphincter, which when contracted, shut off blood supply to that particular capillary bed and when these sphincters relax, blood flows into the capillary beds. Control of this blood shunting is through the sympathetic nervous system. Stimulation by impulses from these nerves causes the smooth muscle in the arterioles and the pre-capillary sphincters to contract and vasoconstriction occurs. In the cardiac muscle and skeletal muscle however, these same sympathetic nerves are vasodilators, increasing the diameter of the blood vessels supplying these tissues.
Shunting also occurs due to local factors. What are these local factors?
Some local factors have a direct effect on vasodilation in working muscles, these include a drop in oxygen and a rise in carbon dioxide levels, an increase in acidity and others which give a instantaneous vasodilation, because these are the result of muscle activity.
When venous return increase during exercise what else does?
Stroke volume is dependent on venous return. Therefore if venous return increases and stroke volume increases, cardiac output will also increase.
Why are mechanisms needed to help increase venous return?
The pressure exerted in the systole phase of each heart beat is too low in the veins to push the blood all the way back to the heart. This means that active mechanisms are needed to help venous return.
What are the four factors that aid venous return and how do they work?
- The Skeletal muscle pump - When muscles contract and relax they change shape. This change in shape means that the muscles press on the nearby veins and cause a pumping effect and squeeze the blood towards the heart.
- The respiratory pump - During breathing in and out, pressure changes occur in the thoracic (chest) and abdominal cavities. These changes in pressure compress the nearby veins and assist blood return to the heart.
- Pocket valves - It is important that blood in veins only flow in one direction. The presence of these valves ensures that this happens. This is because once the blood has passed through the valves, they close to prevent the blood flowing back.
- Gravity helps the blood return to the heart from the upper body.
- Suction pump action of the heart.
Why is it important to cool down after exercising?
If you suddenly stop exercising, the skeletal muscle pump slows, even though the heart is still working hard whilst you recover. This results in blood “pooling” in the muscles, which means that less is reaching the heart, and therefore less is being pumped out. The first organ to suffer from a lack of blood is the brain, and athletes can get dizzy or even faint from this mechanism.
Where does the blood move the fastest?
It moves fastest in the large arteries, slower in small arterioles and veins, and slowest in the capillaries.
What does the velocity of blood depend on?
The velocity of the blood is related to the cross sectional area of the blood vessel it is passing through. The smaller the cross sectional area the faster the blood flows.
Why does blood not flow fastest in the capillaries?
Although the capillaries are the smallest blood vessels, the fact that there are so many means that there cross sectional area is much greater than the aorta. This means the blood flow in the capillaries is slower which allows time for efficient gas exchange within tissues.
Once the blood has left capillaries what happens to its velocity?
It increases as the cross sectional area decreases as it enters the venues and veins.
What is the effect of exercise on blood volume?
Blood volume changes during exercise. A decrease in blood volume occurs during exercise when plasma moves out of the capillaries into the surrounding tissues.
What is the cardiac respiratory system?
The combination of breathing, respiration and transporting the gases to and from the cells is undertaken by the cardio-respiratory system.
What are macro nutrients?
Carbohydrates, proteins and fats
What is external respiration?
The process of exchanging gases in the lung is known as external respiration.
When you breath in what is order of where the oxygen travels to the lungs? (Acronym)
Nearly - Nose Lobbed - Larynx The - Trachea Ball - Bronchi Brilliantly - Bronchioles
What protects the lungs?
- The rib cage physically protects the lungs.
- The pleura is a double layer of membrane that contains lubricating pleural fluid to reduce friction.
- The diaphragm separates the lungs from the abdomen (a large sheet of skeletal muscle)
When the air enters the nose what happens to it?
It is warmed and humidified and filtered by a thick mucous membrane.
What is the larynx also known as?
The voice box
What is the trachea also know as?
The windpipe
What are the properties of the trachea?
- Approximately 10cm
- Held open by rings of cartilage
- Mucous and ciliated cells line the trachea and filter the air.
- The trachea divides into the right and left bronchi.
Where are the alveoli located?
They are attached to bronchioles which are attached to the bronchi in the lungs.
What is the importance of the alveoli?
The alveoli are responsible for the exchange of gases between the lungs and the blood.
What are the characteristics of the alveoli?
- Walls are very thin (one cell thick)
- Dense capillary network surrounds them
- Huge surface area which allows for greater uptake of oxygen.
What happens during inspiration?
Increasing the thoracic cavity reduces the pressure of the air in the lungs. This happens when the surrounding lungs contract. At the bottom, the diaphragm contacts so that flattens, while the external intercostals contract, pulling the ribs up and out.
What happens during expiration?
Decreasing the volume of the thoracic cavity increases the pressure of air in the lungs, forcing the air out. At rest expiration is passive (muscles relax). The diaphragm and external intercostal muscles relax and the volume of the thoracic cavity is decreased. Lungs move down and in.
What is the main difference in expiration during exercise?
It is an active process rather than a passive one. Muscles contract during expiration (internal intercostal muscles and abdominals)
What are the extra muscles used in inspiration during exercise?
As well as the Diaphragm and the intercostal muscles which are always used, there are three other important muscles that increase the inspiration rate:
- Sternocleidomastoid - Lifts the sternum
- Pectoralis minor - helps to lift the ribs
- Scalenes - helps to lift the ribs
What are the extra muscles used in expiration during exercise?
Internal intercostal muscles - pull the ribs down and in
Abdominals - push the diaphragm up
What is tidal volume?
Volume of air breathed in or out per breath.
What is inspiratory reserve volume (IRV)?
Volume of air that can be forcibly inspired after a normal breath.
What is expiratory reserve volume (ERV)?
Volume of air that can be forcibly expired after a normal breath.
What is residual volume?
Volume of air that remains in the lungs after maximum expiration.
What is minute ventilation (Ve)?
Volume of air breathed in or out per minute.
What happens to tidal volume during exercise?
Increases
What happens to the Inspiratory reserve volume during exercise?
Decreases
What happens to the Expiratory reserve volume during exercise?
Slightly decreases
What happens to the residual volume during exercise?
It remains the same.
What happens to minute ventilation during exercise?
There is a big increase
How do you work out the minute ventilation?
Number of breaths per minute (frequency) x volume of breath per minute (tidal volume)
What is vital capacity?
The largest amount of that can be exhaled after a maximum inhalation. (Usually 4-5 litres) It is the total lung capacity minus the residual volume.
What is the vital capacity a combination of?
IRV + ERV + Tidal volume
What is pulmonary ventilation?
Movement of air into and out of the lungs.
What is the average breathing rate at rest?
12-15 breaths per minute
What is the average Tidal volume at rest?
0.5 litres
Using the knowledge that a person has 12 breaths per minute and a tidal volume of 0.5 litres work out their minute ventilation.
12 x 0.5 = 6 litres
What can minute ventilation increase up to during exercise?
180 litres
How is such a large increase in minute ventilation achieved during exercise?
The breathing rate increases its frequency and depth
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.
What is gaseous exchange?
The movement of oxygen from the air into the blood and carbon dioxide from the blood into the air.
What is a spirometer?
A device that is used to measure the volume of air inspired and expired by the lungs.
Why is there an increased demand for oxygen during exercise?
To produce energy for the muscles as oxygen is needed in aerobic respiration.
What is the importance of the conduction system?
The conduction system ensures that the heart rate increases during exercise to allow the working muscles to receive more oxygen.
What is the nervous system made up of?
Two main parts:
- The central nervous system - consists of the brain and the spinal cord.
- The peripheral nervous system - nerve cells that transmit information to and from the CNS
How do baroreceptors detect changes in blood pressure?
They contain nerve endings that respond to stretching of the arterial wall caused by changes in blood pressure.
What does an increase in arterial pressure (baroreceptors detect change) cause?
A decrease in heart rate and a decrease in arterial pressure increases the heart rate.
What is the difference between mechanoreceptors and proprioceptors?
Mechanoreceptors detect a change in muscle movement whereas proprioceptors detect change movement and position of muscles, tendons and joints.
What are the three factors that control the breathing rate?
- Neural control
- Chemical control
- Hormonal control
Where does neural control of the respiratory system occur and what two main areas does it make up?
The respiratory control centre (RCC) in the medulla oblongata of the brain is responsible for the control of breathing. This is made up of two main areas:
- Inspiratory Control Centre (ICC)
- Expiratory Control Centre (ECC)
What is the inspiratory centre stimulated by?
- Chemoreceptors
- Baroreceptors
- Proprioceptors
What is the expiratory centre stimulated by?
Lung stretch receptors
How does the inspiratory control centre stimulate inspiratory muscles?
The inspiratory centre sends out nerve impulses via the phrenic nerve to the inspiratory muscles (diaphragm and external intercostal muscles) to cause them to contract to move the lungs and ribs up and out. The stimulation acts for approximately 2 seconds.
What is the expiratory centres response to stimulation?
The expiratory centre stimulates the expiratory muscles during exercise (abdominals and internal intercostal muscles) to move the lungs and ribs down and in.
How does the Respiratory centre respond to changes in blood chemistry?
During exercise, blood acidity increases as a result of an increase in the plasma concentration of carbon dioxide and an increase in lactic acid production. These changes are detected by chemoreceptors, which are found in the carotid arteries and aortic arch and they send impulses to the inspiratory centre to increase ventilation until the blood acidity has returned to normal. This is achieved by the Respiratory centre sending impulses down the phrenic nerve to stimulate more inspiratory muscles; sternocleidomastoid, scalenes and pectoralis major.
What factors affect the neural control of breathing?
- Proprioceptors - Sensory receptors located in the joints and muscles that provide feedback to the respiratory centre to increase breathing during exercise.
- Baroreceptors - a decrease in blood pressure detected by baroreceptors in the aorta and the carotid arteries results an increase in breathing rate.
- Stretch receptors - during exercise the lungs are stretched more. Stretch receptors prevent over-inflation of the lungs by sending impulses to the expiratory centre and the down the intercostal nerve to the expiratory muscles (abdominals and internal intercostals) so that expiration occurs.
What are the effects of training on lung function?
- Small increases in lung volumes and capacities.
- Improved transport of respiratory gases, oxygen and carbon dioxide.
- More efficient gaseous exchange at the alveoli tissues (more alveoli sacks).
- Improved uptake of oxygen by the muscles (more capillary beds)
Due to prolonged endurance training what changes can it cause?
Changes in the composition of the blood:
-Increase in the total volume of the blood
-Increase in the number of red blood cells
-Leads to an increase of haemoglobin
These changes provide for increased oxygen delivery to the muscles and more efficient removal of carbon dioxide.
How does smoking affect the respiratory system?
- Causes irritation of the trachea and bronchi.
- Increases breathlessness caused by the swelling and narrowing of the lungs’ airways.
- Cigarette smoking damages the cells lining the trachea, bronchi and bronchioles. These cells have tiny microscopic hair-like cilia on their surface, which help to push mucus out of the lungs. Whe they are damaged, excess mucus builds up in the lung passages, which leads to smokers cough to try and get rid of the mucus.
- Damages the alveoli as their walls break down and join together forming larger air spaces than normal. This reduces the efficiency of gaseous exchange, which increases the risk of Chronic Obstructive Pulmonary Disease.
- Haemoglobin in red blood cells has a higher affinity for carbon monoxide from cigarettes than oxygen. This reduces the oxygen-carrying capacity of the blood, which increases breathlessness during exercise.
How do you improve oxygen uptake by the muscles?
- Endurance training improves the ability of the skeletal muscle to extract oxygen from the blood.
- This is largely due to an increase in mitochondrial density and myoglobin content.
- This increase in oxygen causes an increase in the arterial venous oxygen difference (a-VO2 diff)
What is the arterial venous oxygen difference(a-vo2)?
This is the difference between the oxygen content between arterial blood and venous blood.
We can use it to measure how much oxygen is actually being consumed in the muscle and tissues.
During exercise it rises from 25% to 85%
What are cilia?
Cilia are microscopic hair like projections that help to sweep away fluids and particles.
What is COPD?
Is a chronic and debilitation disease and is the name for the collection of diseases such as emphysema. The main cause of emphysema is smoking. It is a long-term, progressive disease of the lungs that causes shortness of breath.
What is partial pressure?
The pressure exerted by an individual gas when it exists within a mixture of gases.
How does the partial pressure of oxygen change as it moves through the human body?
At sea level the partial pressure is 160mmHG. By the time the air reaches the alveoli the partial pressure of oxygen (pO2) has dropped to around 100mmHG. In the blood vessels surrounding the lungs it drops to 40mmHG because the oxygen has been removed by the tissues so its concentration in the blood is lower.
Why does oxygen in the alveoli diffuse into the surrounding blood vessels?
The partial pressure of oxygen in the alveoli is 100mmHG whereas it is 40mmHG in the blood vessels. This concentration gradient is large which means the oxygen moves from the high concentration in the alveoli to the low concentration in the blood vessels.
How does the partial pressure of carbon dioxide change as it moves through the human body?
Carbon dioxide diffuses from the capillaries surrounding the lungs to the alveoli because in the capillaries the partial pressure of CO2 is 45mmHG but in the alveoli it is 40mmHG. It is then expired.
What is a buffer and what is an example in our body?
A buffer is a substance that combines with either an acid or a base to help keep the body’s pH at an optimum level. Haemoglobin combined with hydrogen ions acts as a buffer.
What is the graph called that represents oxyhaemoglobin compared to its partial pressure?
The oxyhaemoglobin dissociation curve.
How do you read the oxyhaemoglobin dissociation curve?
Backwards
What factors cause the level of saturation of oxygen to haemoglobin?
- Blood temperature - When blood and muscle temperature increases during exercise, O2 dissociates from haemoglobin more readily.
- Partial pressure of CO2 - As levels rise during exercise, oxygen dissociates itself quicker from haemoglobin.
- pH - More carbon dioxide will lower the pH in the blood. A drop in blood pH will cause oxygen to dissociate from haemoglobin more quickly.
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 than haemoglobin. It stores the oxygen in the muscle fibres which can be used quickly when exercise begins.
How does myoglobin get its oxygen stores?
By picking it up the oxygen released by the haemoglobin. Oxygen therefore diffuses via the myoglobin across muscle cells to cell mitochondria.
Why is myoglobin beneficial?
Unlike haemoglobin, myoglobin remains fully saturated, ensuring good oxygen supply to the muscle tissue. It is seen as a storage unit, so when the muscles contract they have a ready supply of oxygen to help in the creation of ATP.
What is plasma?
The fluid part of blood (mainly water) that surrounds the blood cells and transports them.
What is haemoglobin?
An iron-containing pigment found in red blood cells, which combines with oxygen to form oxyhaemoglobin.
What are mitochondria?
Often referred to as the ‘powerhouse’ of the cell as respiration and energy production occurs there.
What is the Bohr shift?
When an increase in blood carbon dioxide and a decrease in pH results in a reduction of the affinity of haemoglobin for oxygen.
What is pH?
A measure of acidity. The range goes from 1-14 anything less than 7 indicates acidity.
Do athletes have high or low buffering?
Athletes have higher buffers compared to the untrained
What is a ligament attached between?
Bone to bone
What is a tendon attached between?
Bone to muscle
Describe the structure of a muscle fibre.
Tendon attaches the muscle to the bone. In the centre of the muscle it is made up of a bundle of fibres up to 20mm across. Around that is a connective tissue sheath which is continuous with the tendon. If you take a muscle fibre from the bundle of fibres they are up to 0.10 mm in diameter and are made up of strands of myofibril which is up to 2.0 nano metres. The myofibril is made up of sections of sarcomere.
What is skeletal muscle?
It is muscle connected to the skeleton which is responsible for movement.
What are the three properties of skeletal muscle?
1) Extensibility - Ability of the muscle tissue to lengthen when contracting and provide the effort required to move the lever system (bones)
2) Elasticity - Ability of muscle tissue to return to its normal resting length once it has been stretched. This enables the muscle to prepare for a series of repeated contractions which is normally required during the performance of exercise.
3) Contractility - Capacity of a muscle to contract or shorten forcibly when stimulated by nerves and hormones.
When looking under a microscope what does skeletal muscle look like?
You can see that the muscle is made up of fibres which have light and dark stripes and therefore this type of muscle is sometimes called striated/striped muscle.
Are the fibres all attached together?
No the skeletal muscle is prepared in such a way that these individual fibres have been teased apart and isolated.
Do muscle fibres run the entire length of a muscle?
Only rarely do individual muscle fibres run the whole length of a muscle; more usually they are connected to other fibres by connective tissues, which is continuous which the tissue that forms tendons.
What are the different types of muscle fibre?
There is a slow twitch and two fast twitch types (type 2A and 2B)
How are types of muscle fibres named/categorised?
According to how quickly they can reach peak tension (contraction).
What are the characteristics of Type 1 / Slow twitch / slow oxidative fibres?
-Slower contraction speed compared to fast twitch fibres
-Better adapted to low intensity, long duration and endurance work
High capacity for aerobic respiration:
-Better blood supply because of a greater number of capillaries per fibre
-More myoglobin which stores oxygen
-More mitochondria
What are type 1 / Slow twitch fibres specialised for?
They are specialised for steady, continuous activity and are highly resistant to fatigue. Their motor neurones are often active, with low firing frequency.
What are the characteristics of fast twitch / Type 2A?
- Fast contraction speed
- Resistant to fatigue
- Motor neurones show bursts of intermittent activity
- Cells are thin (high surface area to volume ratio)
- Have a good supply of capillaries for efficient gas exchange
- Rich in mitochondria and myoglobin
- Built for aerobic metabolism
What are the characteristics of type 2B muscle fibres?
- Fast contraction speed
- High myosin ATPase activity
- Easily fatigue
- Motor neurones transmit occasional bursts of very high frequency impulses
- Large cells with poor surface to volume ratio
- Limited capillary supply slows the delivery of oxygen and the removal of waste products.
- Few mitochondria and little myoglobin
- Generate ATP by anaerobic respiration (fermentation of glucose to lactic acid)
Give an example of an activity that uses Slow twitch fibres?
Marathon running
Give an activity that uses type 2A muscle fibres?
Badminton play apart from the smash
Give an activity that uses type 2B muscle fibres?
Sprinters
What colour are Type 1 muscle fibres?
A dark red with a high blood supply.
What colour are Type 2 muscle fibres?
White colour with very limited blood supply.
What are the differences between fast and slow twitch fibres?
Fast twitch: Slow twitch:
- Fast/non-rhythmical contractions -Slow/rhythmical
- Larger cross section. -smaller
- Higher force produced. -less
- Less energy efficient -more
- Adapted for short duration exercise -long duration exercise
- Non-resistant to fatigue -resistant
Do different muscles have different muscle types?
Yes, further up the body tends to be more fast twitch whereas lower down the body there is more slow twitch.
You are born with variant distribution of fast and slow twitch muscles fibres although the average is 50% to 50%. Can you change these through training?
You inherit the type of muscle twitch fibres and you cannot change them through training.
Why are type 1 muscle fibres best for endurance?
- High oxidative capacity
- low anaerobic capacity
- high fatigue resistance
- many mitochondria
- many capillaries.
What is the effect of training on the skeletal muscle?
Increase in fibre thickness. Mitochondria, blood capillaries, glycogen stores, fat vacuoles all increase.
What does aerobic mean?
Literally means ‘with oxygen’ so it refers to exercise that is low to medium intensity where the oxygen demand for muscles can be met.
What does anaerobic mean?
Means ‘without oxygen’ and refers to exercise at high intensity such as sprinting, where the demand for oxygen by the muscles is so high that it cannot be met.
What does pH stand for?
Potential of Hydrogen
How does a muscle contraction occur?
When a muscle is required to contract, an electrical impulse is emitted from the central nervous system. The electrical impulse begins at the brain and is transmitted to a muscle via the spinal cord and by nerve cells called motor neurones.
Can one motor neurone stimulate the whole muscle?
No, it is only capable of stimulating a number of fibres within.
What does the number of fibres innervated by a motor neurone depend on?
The precision of the movement required.
What is a motor unit?
A motor neurone and its muscle fibres.
What is a motor neurone?
Nerve cells which transmit the brain’s instructions as electrical impulses to the muscles.
What is neuromuscular junction?
Where the motor neurone and the muscle fibre meet.
Can there be different types of muscle fibre in a motor unit?
No, only one type of muscle fibre can be found in one particular motor unit.
For muscle that are responsible for fine motor control, do there motor units have a high or low amount muscle fibres?
A small muscle that is used for fine motor control, the muscle controlling eye movements, will have motor units that have only a few fibres per motor neurone.
What is the all or none law?
Where a sequence of impulses has to be a sufficient intensity to stimulate all of the muscles fibres in a motor unit in order for them to contract. If not, none of them contract.
What is wave summation?
Where there is a repeated nerve impulse with no time to relax so a smooth, sustained contraction occurs, rather than twitches.
What is a tetanic contraction?
A sustained muscle contraction caused by a series of fast repeating stimuli.
What is spatial summation?
When the strength of a contraction changes by altering the number and size of the muscles motor units.
When does spatial summation occur?
This occurs when impulses are received at the same time at different places on the neurone which add up to fire the neurone. It is the recruitment of additional bigger motor units within a muscle to develop more force.
Give an example of spatial summation?
A basketball player will use lots of large, fast twitch motor unit units in their quadriceps muscles to try achieve as much height as possible as they jump for the rebound.
What are muscle spindles?
These detect how far and how fast a muscle is being stretched and produce the stretch reflex.
What are golgi tendon organs?
These are activated when there is tension in a muscle.
What is Proprioceptive Neuromuscular Facilitation?
Is an advanced stretching technique and is considered to be one of the effective forms of flexibility training for increasing range of motion.
What is the most common type of PNF?
The CRAC technique ( contract-relax-antagonist-contract)
What is the role of muscle spindles in PNF?
These are very sensitive proprioceptors that lie between skeletal muscle fibres. They are often called stretch receptors as they provide information (excitory signals) to the central nervous system about how fast and how far a muscle is being stretched. The central nervous then sends an impulse back to the muscle telling it to contract, which triggers the stretch reflex. This reflex action that causes the muscle to contract to prevent over stretching reduces the risk of injury.
What is the role of golgi tendon organs in PNF?
These are found between the muscle fibre and the tendon. They detect levels of tension in a muscle. When the muscle is contracted isometrically in PNF, they sense the increase in the muscle tension and send inhibitory signals to the brain which allows the antagonist muscle to relax and lengthen. This is known as autogenic inhibition.
What is an isometric contraction?
Where there is tension in a muscle but no visible movement.
What are autogenic inhibition?
Where there is a sudden relaxation of the muscle in response to high tension. The receptors involved in this process are golgi tendon organs.
PNF in practice - Describe how the muscle spindles and golgi tendon organs work?
An individual performs a passive stretch with the help of a partner who extends there leg towards their head until a stretch is felt. This stretch is detected by muscle spindles. The individual the isometrically contracts the muscle for at least 10 seconds by pushing their against their partner who supplies just enough resistance to hold the leg in a stationary position. At this point golgi tendon organs are sensitive to the tension developed in the muscle and during the isometric contraction they are activated and the inhibitory signals they send override the excitory signals from the muscle spindles, therefore delaying the stretch reflex. As the leg is lifted again, the golgi tendon organs are responsible for the antagonist muscle relaxing, which means the leg stretches further. This process can be repeated until no more gains are possible.
What is the difference between what the muscle spindles and golgi tendon organs detect?
Muscle spindles signal changes in the length of the muscle, while golgi tendon organs signal information about the load or force being applied to the muscle.
What are the three types of joints?
- Fibrous (fixed)
- Cartilaginous (slightly moveable joints)
- Synovial joints (freely moveable joints)
Define articulating
This refers to the bones that meet and move at the joint.
What type of movement do ball and socket joints allow?
The joint allows movement in every direction.
How is a ball and socket joint formed?
Formed by the round head of one bone fitting into the cup-shaped capsule of the connecting bone.
Name two examples of a ball and socket joints
- Shoulder
- Hip
What are the articulating bones at the shoulder?
The humerus and scapula
What are the articulating bones at the hip?
Femur and pelvis
What are the two types of synovial joints?
- Ball and socket
- hinge
What type of movement do hinge joints allow?
The hinge joint only allows movement in one direction, due to the shape of the bones making up the joint.
Name three examples of hinge joints?
- Ankle
- Knee
- Elbow
What are the articulating bones at the ankle?
Talus, tibia and fibula.
What are the articulating bones at the knee?
Femur and tibia
What are the articulating bones at the elbow?
Radius and ulna
What are the three planes?
- Sagittal
- Frontal
- Transverse
What is the sagittal plane?
Divides the body into right and left halves.
What is the frontal plane?
Divides the body into front and back halves.
What is the transverse plane?
Divides the body into upper and lower halves.
Which two planes are vertical?
Sagittal and frontal
What are the three axis?
- Transverse
- Sagittal
- Longitudinal
What is the transverse axis?
Runs from side to side across the body.
What is the sagittal axis?
Runs from front to back.
What is the longitudinal axis?
Runs from top to bottom.
What is flexion?
Decreasing the angle between the bones and joint.
What is extension?
Increasing the angle between the bones of a joint.
What is Plantar-flexion?
Pointing the toes/pushing up on your toes.
What is Doris-flexion?
Pulling the toes up to your shin.
What is hyper-extension?
Increasing the angle beyond 180 degrees between the bones of a joint.
What occurs in a sagittal plane about a transverse axis?
- Flexion
- Extension
- Plantar-flexion
- Dorsi-flexion
- hyper-extension
What occurs on a frontal plane about a sagittal axis?
- Abduction
- Adduction
What occurs on a transverse plane about a longitudinal axis?
Horizontal abduction and horizontal adduction
The extension and flexion rule does not apply to what?
To the shoulder it is opposite. E.g raising your arm is flexion rather than extension
What is abduction?
Is the movement away from the midline of the body.
What is adduction?
Is the movement towards the midline of the body.
What is horizontal adduction?
Is the movement of the arm forward across the body at 90 degrees to shoulder abduction.
What is horizontal abduction?
Is the movement of the arm backwards across the body to shoulder abduction.
Define agonist
The muscle that is responsible for the movement that is occurring.
Define antagonist
The muscle that works in opposite to the agonist (to help produce a co-ordinated movement).
A joint cannot move by itself, it needs muscles to move bones into position. When a muscle contracts what happens?
One end of the muscle is anchored in place and the other end pulls the bone, causing movement.
Give an example of an agonist and antagonist and describe how they work.
When the bicep contracts, it is responsible for the movement that is occurring and is said to be acting as an agonist. There can be more than one agonist acting at a joint although this does depend on the type of movement that is being performed. An antagonist muscle is one that works in opposition to the agonist, so when the bicep is contracting, the triceps is lengthening and acting as an antagonist.
What is an antagonistic muscle action?
It is when one muscle is acting as an agonist and the other is acting as an antagonist and therefore the muscles are said to be working together as a pair to produce the required movement.
What is a concentric contraction?
When a muscle shortens under tension.
What is an eccentric contraction?
When a muscle lengthens under tension or performs negative work and acts like a brake.
What are the two types of isotonic contractions?
- Concentric
- Eccentric
What happens during an isometric contraction?
A muscle contracts without actually lengthening or shortening.
Using a bicep curl describe the different muscular contractions that occur.
A) During the upward phase, the bicep brachii contracts to produce flexion of the elbow joint. In this situation it is performing a concentric contraction.
B) During the downward phase, there is still tension. The muscle is not relaxing but performing an eccentric contraction where it lengths under tension.
C) If the weight is held still at a 90 degree angle, the bicep brachii is under tension even though we do not see any movement. This is an isometric contraction.
What is a good example of an isometric contraction.
The crucifix position in a gymnastic
How do chemoreceptors work?
During exercise, these detect an increase in carbon dioxide. The role of blood carbon dioxide is important in controlling heart rate. An increased concentration of carbon dioxide in the blood will have the effect of stimulating the sympathetic nervous system, causing the heart to beat faster.
How do baroreceptors work?
Baroreceptors contain nerve endings that respond to the stretching of the arterial wall caused by changes in blood pressure. Baroreceptors establish a set point for blood pressure. An increase above or decrease below this set point results in the baroreceptors sending signals to the medulla in the brain. An increase in arterial pressure causes an increase in the stretch of the baroreceptor sensors and results in a decrease in heart rate. Conversely, a decrease in arterial pressure causes a decrease in the stretch of the baroreceptors and results in an increase in heart rate.
What happens to the baroreceptors set point during exercise?
At the start of exercise the baroreceptor set point increases, which is important as the body does not want heart rate to slow down as this would negatively affect performance, as less oxygen would be delivered to the working muscles.
How do proprioceptors work?
At the start of exercise, they detect an increase in muscle movement movement. These receptors then send an impulse to the medulla, which then sends an impulse through the sympathetic nervous system to the SAN to increase heart rate. When the parasympathetic nervous system stimulates the SAN, heart rate decreases.
Why does stroke volume begin to decrease at a high intensity of exercise?
It results in a shorter diastolic phase which means the ventricles do not have as much time to fill up with blood, so they cannot pump as much out.
When does coronary heart disease occur?
When your coronary arteries, which supply the heart muscle with oxygenated blood, become blocked or start to narrow by a gradual build of fatty deposits (atheroma). High blood pressure, high levels of cholesterol, lack of exercise and smoking can all cause atherosclerosis.
Why does regular exercise reduce your chance of getting atherosclerosis?
Regular exercise keeps the heart healthy and efficient. The heart can pump more blood around the body as exercise makes the heart bigger and stronger resulting in an increase in stroke volume. Regular exercise also maintains the flexibility of blood vessels, ensuring blood flow, normal blood pressure and low cholesterol levels.
What are Low density lipoproteins?
These transport cholesterol in the blood to the tissues and are classed as bad cholesterol since they are linked to an increased risk of heart disease. This is because once the tissues have absorbed enough, the excess LDLs overload these membrane receptors, resulting in high blood cholesterol levels. This LDL cholesterol may be deposited in the artery wall forming atheroma.
What are high density lipoproteins?
These transport excess cholesterol in the blood back to the liver where it broken down. These are classed as good cholesterol since they lower the risk of developing heart disease.
What are the two types of strokes?
- Ischaemic
- Haemorrhagic
What is a ischaemic stroke?
The most common form which occur when a blood clot stops the blood supply.
What is a haemorrhagic stroke?
A stroke that occurs when a weakened blood vessel supplying the brain bursts.
What is the impact of blood pressure on venous return?
When systolic pressure increases, venous return increases and when systolic pressure decreases, venous return decreases.
What is the calculation for peripheral vascular resistance?
Venous pressure (Pv) - right atrial pressure (Pra) / venous vascular resistance (Rv)
What is vasodilation?
The widening of blood vessels to increase the flow of blood into the capillaries.
What is vasoconstriction?
The narrowing of blood vessels to reduce blood flow into the capillaries.
What is the vascular shunt mechanism?
The redistribution of cardiac output.
What is the nerve that sends impulses to cause an increase in breathing rate?
Phrenic nerve
What is the nerve that sends impulses to cause an increase in expiration?
Intercostal nerve
What is the sinistral node also known as?
It is more commonly called the pacemaker.
Describe how the inspiratory rate is increased.
Receptors (barorectors, chemoreceptors and proprioceptors) send impulses to the inspiratory centre in the medulla oblongata. The respiratory centre then sends a nerve impulse down the phrenic nerve which causes the diaphragm and external intercostal to contract and increase the breathing rate.
Describe how the expiratory rate is increased.
Stretch receptors send impulses to the expiratory centre. The respiratory centre found in the medulla oblongata sends nerve impulses along the intercostal nerve which causes the abdominals and internal intercostals to contract, increasing expiration.
Describe the hormonal regulation of pulmonary ventilation during exercise.
Just before we start exercising, the brain sends impulses to the renal gland which responds by pumping adrenaline into the blood in anticipation of the increased need for oxygen and carbon dioxide exchange. As a result, breathing rate increases in preparation for exercise and the demand to take in more oxygen and remove moe carbon dioxide.
What is the function of the sympathetic system regarding the respiratory system?
The sympathetic nervous system prepares your body for exercise and increases breathing rate.
What is the function of the parasympathetic system regarding the respiratory system?
The parasympathetic nervous system lowers breathing rate.
What is the function of the inspiratory centre?
The inspiratory centre is responsible for inspiration and expiration.
