The Heart Flashcards
Explain the double circulatory system of the heart.
Pulmonary ventilation is where the right hand side of the heart sends deoxygenated blood from the heart to the lungs, via the pulmonary artery.
Systematic ventilation is where the left hand side of the heart sends oxygenated blood from the heart to the rest of the body, via the aorta.
Why is it advantageous for the human body to have a double circulatory system?
Having two seperate pumps allows the left hand side to generate much more pressure to transport oxygenated blood around the body fast enough to maintain a high metabollic rate.
Where are the coronary arteries found and what is their function?
They are found on the surface of the heart, and they trabsport oxygenated blood to 5he cardiac muscles that make up the walls of the heart. This allows the cells to have a high rate of aerobic respiration for muscle contraction.
Describe the structure and functions of the atria
Thinnly walled upper chambers of each side of the heart.
They recieve blood from the Vena Cava/pulmonary vein and contract to move blood throigh the atrioventricular valves into the ventricles
Describe the structure and function of the venticles
They are lower chambers of the heart with very thick muscular walls. The right ventricle pumps deoxygenated blood through the pulmonary artery to the lungs. The left ventricle pumps oxygenated blood through the aorta to the rest of ten body.
What is the septum?
A wall of muscle that separates the right and left chambers of the heart.
What are the roles of the atrioventricular and semilunar valves?
Atrioventricular valves prevent backflow from the venticles to the atrium
Semilunar valves orevent backflow from the arteries to the ventricles
What are the tendinous cords?
They are innelastic connective tissues that are attatched to the AV valves and prevent them from inverting.
Why are muscles of the left ventricle much thicker than those of the right ventricle?
So they can contract with more force to generate a higher pressure so it can pump blood furtehr, aroun dthe rest of the body
What is the cardiac cycle?
One complete sequence of the contraction and relaxation of cardiac muscles in the heart, which pumps blood around the body
How does blood move?
From areas of high pressure to areas of low pressure
State the three stages of the cardiac cycle
Diastole, atrial systole, ventricular systole.
Describe ethe stages of diastole during the cardiac cycle
Hesrt muscles relax and both atria fill with blood from the vena cava or pulmonary vein
Pressure is higher in the arteries than the ventricles so the semilunar valves are closed to lrevent backflow
Describe atrial systole of the cardiac cycle
As blood fills the atria. The atrial muscles contract to decrease the volume and therefore increase the pressure. This forces the AV valves to open, blood moves into the ventricles down a pressure gradient.
Describe the ventricular systole of the cardiac cycle
Ventricular muscles contract, the volume decreases and the pressure increases.
AV valves close to prevent backflow as pressure is higher in ventricles than atrium.
Blood is pushed upwards towards arteries at the top of the heart, forcing SL valves to open. Blood foows down pressure gradient into aorta/pulmonary arteries
Are cardiac muscles myogenic or neurogenic? Explain why
Myogenic, as the contractions arise from within the cardiac muscles themselves, instead of from impulses semt from the nervous system.
Where does the initial stimulation for muscle contractions in the heart start?
In the sinoatrial nodes (SAN) in the right atrium.
Explain how the cardiac cycle is controlled
A wave of electrocal impulses are sent from the SAN and spread across both atria, causing them to contract.
The impulse reaches the Atriaventricular nodes and is delayed, allowing the atria to fully empty into the ventricles.
After the delay, the impulse spreads to the bundle of hiss in the ventricles.
The impulse is transmitted to the base of the ventricles where it then passes up the purkyne fibres, causing the ventricles to contract from the base upwards.
What is stroke volume and what is it measured in?
Stroke volume is the volume of blood pumped out of the ventricle during each cardiac cyle
Measured in cm3
What is cardiac output?
The total volume of blood pumped out of one ventricle in one minute
What is the equation for cardiac output?
Stroke volume x heart rate
What is the advantage of increasing cardiac output during exercise?
More oxygenated blood is pumped around the body, more oxygen and glucose is transported to cells, faster rate of aerobic respiration, more ATP produced for muscle contractions.
What unit is cardiac output measured in?
dm3min-1
Why do mammals require a circulatory system?
So cells can recieve oxygen and glucose fast enough to maintain a high metabollic rate
What is mass transport?
The movement of substances from one area to another due to the differences in pressure
What is the difference between pulmonary and systematic circulation?
Pulmonary circulation is the mass transport of blood around the lungs
Systematic circulation is the mass transport of blood around the body
Describe mass flow around the kidneys
The renal artery transports oxygenated blood to the kidneys
The renal vein transports deoxygenated blood away from the kidneys
Describe mass flow around the liver
The hepatic artery carries oxygenated blood to the liver
The hepatic vein carries deoxygenated blood away from the liver
The hepatic portal vein transports deoxygenated blood from the small intestine to the liver
What are blood vessels and name the three main blood vessels in mammals
Blood vessels are tubes with spaces in the centre called a lumen, where blood flows and is transported.
Capillaries, veins, arteries
What is the function of capillaries?
They branch of from arterioles and create a network of tubes in tissues where materials are exchanged between blood and cells
State and explain 5 adaptations of capillaries
- Contain pores, highly permeable
- low blood pressure so blood flows slower, allowing more time for the exchange of materials.
- walls consist of single endothelial cells, which provide a short diffusion pathway for diffusion lf oxygen
- numerous and branched to provide large SA for diffusion.
- narrow lumen which pushes red blood cells against walls to decrease diffusion pathway for oxygen
What is the function of arteries?
Arteries carry oxigenated blood away from the heart (exept for the oulmonary artery) and branch into smaller vessels called arterioles
Describe 4 characteristics of arteries and why they are necessary
No valves, as blood is constantly at high pressure so unlikely to flow backwards
Thick muscular walls, controlls volume of blood into tissues by contracting (which constricts arterioles) and relaxing (which causes arterioles to dialate)
Thick vessel wall withstands high pressure, stops vessel bursting under high pressure
Thick elastic tissue allows vessel to stretch and recoil to maintain high pressure and smooth blood when surges are send from contractions of the heart
What is the function of veins?
Carry deoxygenated blood (exept pulmonary vein) towards the heart
What is the name for very small veins, and very small arteries?
Small veins are called venules
Small arteries are called arterioles
Describe 4 characteristics of veins and why they are necessary
Have valves to prevent backflow of blood due to low pressure.
Overall thickness of the vessel wall is small, allowing veins to be compressed and flattened which can aid blood flow
Thinner muscular walls (than arteries) as they carry blood away from tissues so dont need to contoll volume lf blood into tissue
Thinner elastic tissue (than arteries) as pressure is low and there are no syrges of blood from the heart to smoothe
Give two examples of prgans that carry blood
Arteries and veins
What is a risk factor?
A factor that increases the probability of developing a disease. They are a correlation not necessarily a causation
Explain what coronaty heart desease is
Layers of fatty materials (called atheroma) build up in the coronary arteries.
This causes them to narrow and restrict blood flow
So less oxygen is transported to the cardiac muscle cells of the heart.
Further atheroma can cause thrombosis (blood clots), which can lead to heart attacks
State 4 unavoidable risk factors for coronary heart disease
Gender (males more likely to develop disease)
Advancing age
Ethnicity
Family history of the disease
State and explain 3 risk factors for coronary heart disease that are a result of lifestyle
Smoking- nicotine increases heart rate and acts as a vasoconstrictor, norrowing the lumen of the artery and increasing blood pressure, increasinh risks of thrombosis
Diet- High levels of salt or cholesterol in the blood that result from diets high in cholesterol and saturated fats can lead to atheroma
High blood pressure (caused by diets, prolonged stress or lack of excersise) damages the arteries endothelium tissue, which can cause atheroma
Hat unique properties do carduac muscles have?
They are myogenic- so contractions can be stimulated from within the muscles rather than from the brain
Contain large amounts of mitochondria for ATP production, for a higher rate of aerobic respiration
What are the units for cardiac output?
litres min-1
/ dm3 min-1
