Circulatory system & the heart Flashcards
Name 2 common features of transport systems of many mammals
- Suitable medium in which to carry materials e.g blood. Is normally a liquid based on water as water readily dissolves substances + can be moved around easily
- Form of mass transport in which transport medium is moved around in bulk over large distances - more rapid than diffusion
- Closed system of tubular vessels + contain transport medium + forms branching network to distribute it to all parts of organism
- Mechanism for moving transport medium within vessels - requires a pressure difference betw. 1 part of the system + another
How can materials be transported in animals & plants?
- Animals use muscular contraction of body muscles/specialised pumping organ e.g heart
- Plants rely of natural passive processes e.g evaporation of water
How can materials be transported in mammals?
- Through a mechanism to maintain mass flow movement in 1 direction (e.g valves)
- By a means of controlling flow of transport medium to suit the changing needs of diff. parts of organism
- Through a mechanism for mass flow of water/gases (e.g intercostal muscles + diaphragm during breathing )
How would you describe the circulatory system of mammals? Explain why it is described this way
Mammals have a closed, double circulatory system.
Blood is confined to vessels + passes twice through the heart for each complete circuit of the body - when blood is passed through the lungs its pressure is reduced + when blood is returned to the heart it boost its pressure before being circulated to rest of tissues
Why is it necessary for substances to be delivered to the rest of the body quickly in mammals?
As mammals have a high body temp. + hence a high rate of metabolism
What process is the final part of the journey to cells after the transport system?
Diffusion
Why is the final exchange from blood vessels to cells rapid?
It takes place over a large SA, across short distances + there is a steep diffusion gradient
What is the heart and where is it found?
A muscular organ found in the thoracic cavity behind the sternum (breastbone) - it operates continuously + tirelessly throughout the life of an organism
Give a very brief description of the structure of the heart (left + right + blood)
- Made up of two separate pumps
- Left deals with oxygenated blood from lungs
- Right deals with deoxygenated blood from the body
Name the two chambers that make up each pump
Atrium & ventricle
What is the problem with having only one pump?
- Lungs have to collect O2 then go to rest of body before returning to heart
- Blood has to pass through tiny capillaries in lungs to present large SA for gas exchange
- Therefore there is a v large drop in pressure + blood flow to rest of body would be v slow (this is why in mammals blood is returned to heart to increase pressure before distributed to rest of body)
- Essential to separate deoxygenated and oxygenated blood
Describe the right ventricle and its function
Pumps blood only to the lungs + has thinner muscular walls than left ventricle
Describe the left ventricle and its function
Thicker muscular wall + therefore it can contract to create enough pressure to pump blood to the rest of the body
Describe how both (pumps) sides of the heart work together
- Pump in time with each other but blood doesn’t mix
- Both atria contract together + both ventricles contract together + pump same vol. of blood
What do valves do and where are they found in the heart?
Valves prevent the backflow of blood into the atria when ventricles contract. They are found in atria and ventricles.
What are the two valves found that prevent backflow of blood into atria when ventricles contract?
- Left atrioventricular (bicuspid) valve
- Right atrioventricular (tricuspid) valve
What is connected to each of the 4 chambers of the heart?
Each of the 4 chambers of the heart connected to large blood vessels that carry blood towards/away from the heart
What are pulmonary vessels?
Vessels connecting heart to lungs
Name the vessels connected to the 4 chambers of the heart
- Aorta
- Vena cava
- Pulmonary artery
- Pulmonary vein
Describe the function of the aorta and name the chamber it is connected to
Aorta is connected to left ventricle + carries oxygenated blood to all parts of body (except lungs)
Describe the function of the vena cava and name the chamber it is connected to
Vena cava is connected to right atrium
It brings deoxygenated blood back from tissues of the body (except lungs)
Describe the function of the pulmonary artery and name the chamber it is connected to
Pulmonary artery is connected to right ventricle
It carries deoxygenated blood to lungs where O2 is replenished + CO2 is removed (unusual for artery to carry deoxy. blood)
Describe the function of the pulmonary vein and name the chamber it is connected to
Pulmonary vein is connected to left atrium
It brings oxygenated blood back from lungs (unusual for vein to carry oxy. blood)
How is oxygen supplied to the heart muscle?
- Heart muscle is supplied with oxygen by its own vessels called the coronary arteries
- Although oxy. blood passed through left side of heart, the heart doesn’t use this O2 to meet its own great respiratory needs
Where are the coronary arteries found?
Coronary arteries branch off aorta shortly after it leaves the heart
What causes the coronary arteries to be blocked? Explain the effect of this blockage
Blood clot can lead to myocardial infarction (heart attack)
because an area of the heart is deprived of blood + therefore oxygen - muscle cells in this region unable to respire (aerobically) + so die
What are the 4 types of blood vessel?
Arteries
Arterioles
Capillaries
Veins
What types if blood vessel are the aorta and the vena cava?
- Aorta is an artery
- Vena cava are veins
Name the basic layered structure of arteries, arterioles + veins (from outwards to inwards)
- Tough fibrous outer layer
- Muscle layer
- Elastic layer
- Thin inner lining (endothelium)
- Lumen (not actually a layer but central cavity of a blood vessel)
Describe the function of the tough fibrous outer layer
It resists pressure changes from both within + outside
Describe the function of the muscle layer
It can contract + so control flow of blood
Describe the function of the elastic layer
It helps maintain blood pressure by stretching + springing back (recoiling)
Describe the function of the thin inner lining (endothelium)
It is smooth to reduce friction + thin to allow diffusion
Describe the function of the lumen
It is the central cavity of a blood vessel through which blood flows
Explain the structural difference between veins + arteries
Same structures (layers) but veins are more wide + arteries are more narrow
What are capillaries made up of?
Only thin lining layer and lumen
Describe the function of arteries
Arteries transport blood rapidly under high pressure from heart to tissue
How is the muscle layer (structure) adapted to the function of the arteries?
Muscle layer is thick compared to veins - means that smaller arteries can be constricted + dilated to control vol. of blood passing through them
How is the elastic layer (structure) adapted to the function of the arteries?
- Elastic layer is relatively thick compared to veins - it is important that blood pressure in arteries is kept high so blood can reach all parts of body
- Elastic wall is stretched at each beat of heart (systole) + springs back when heart relaxes (diastole)
- Stretching + recoiling action helps to maintain high blood P + smooth P surges created by beating of heart
How is the overall wall adapted to the function of the arteries?
Overall thickness of wall is great - this resists vessel from bursting under pressure
Why don’t the arteries have valves (except in arteries leaving the heart)?
The blood is under constant high pressure due to heart pumping blood into arteries - therefore tends not to flow backwards
Describe the function of the arterioles
The arterioles carry blood under lower pressure than arteries, from arteries to capillaries + control flow of blood between the two
How is the muscle layer adapted to the function of the arterioles?
Muscle layer is relatively thicker than in arteries - contraction of this layer allows constriction of lumen of arteriole. This restricts flow of blood + so controls its movement into capillaries that supply tissues with blood
How is the elastic layer adapted to the function of the arterioles?
Elastic layer is relatively thinner than in arteries as blood pressure is lower
Describe the function of veins
Veins transport blood slowly, under low pressure from capillaries in tissues to heart
How is the muscle layer adapted to the function of the veins?
Muscle layer is relatively thin compared to arteries -
as veins carry blood away from tissues + therefore their constriction + dilation cannot control flow of blood to tissues
How is the elastic layer adapted to the function of the veins?
Elastic layer is relatively thin compared to arteries -
as low pressure (P) of blood within veins will not cause them to burst + P is too low to create recoil action
How is the overall wall adapted to the function of the veins?
Overall thickness of wall is small -
]as there is no need for thick wall as pressure within veins is too low to create any risk of bursting.
Allows them to be flattened easily, aiding flow of blood
How are the valves adapted to the function of the veins?
- Valves at intervals throughout veins -
to ensure blood doesn’t flow backwards, which it might otherwise do as pressure (P) is too low. - When muscles contract, veins are compressed, pressurizing blood within them
- Valves ensure this P directs blood in one direction only (towards heart)
Describe the function of the capillaries
- Exchange of metabolic materials e.g O2, CO2 + glucose between blood + cells of body
- Flow of blood in capillaries i much slower which allows more time for exchange in materials
How are the walls adapted to the function of the capillaries?
Capillary walls consist mostly of lining layer - makes them extremely thin (1 cell thick), so there is short distance over which diffusion happens.
Allows for rapid diffusion of materials between blood + cells
What feature of the capillaries provides large SA for exchange?
Numerous + highly branched
How is the diameter of the capillaries adapted to its function?
Capillaries have narrow diameter - so they can permeate (spread out) tissues which means that no cell is far from a capillary + there is a short diffusion pathway
How is the lumen adapted to the function of the capillaries?
Lumen is so narrow that red blood cells are squeezed flat against side of capillary + this brings them even closer to cells to which they supply O2 which again reduces diffusion distance
How do the spaces between lining (endothelium) cells help capillaries with their function?
The spaces between lining cells allow white blood cells to escape in order to deal with infections within tissues
What is tissue fluid?
Tissue fluid is the liquid solution that bathes the tissues
Where are the final journey of metabolic tissues made?
The final journey of metabolic materials is made in the tissue fluid
