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)