Circulatory system Flashcards
where is the tricuspid valve located?
between the right atrium and ventricle, stopping the back flow of the blood
which wall of the heart is thicker and why?
the left side. because the muscles need to contract more in order to pump the blood to the rest of the body
what is the function of the pulmonary artery?
carries deoxygenated blood from the right ventricle to the lungs. (OUT THE HEART)
what does the pulmonary vein do?
carries oxygenated blood from the lungs to the left atrium.
what is the part separating the chambers of the heart?
atrial septum
what is the general name for the heart muscle?
the cardiac muscle
what does the left atrium receive ?
blood returning from the lungs
what does the inferior vena cava do?
returns deoxygenated blood to the heart from the lower body.
what does the superior vena cava do?
carries deoxygenated blood to the heart from the head + arms
where is the bicuspid valve located
the left side of the heart between the ventricle and atrium
what are the pulmonary + aortic valves called
semi-lunar valves
what does the right ventricle do?
send deoxygenated blood to the lungs to be oxygenated
what does the aorta do?
carries oxygenated blood to the rest of the body. from the left ventricle.
what is the function of coronary arteries?
carry oxygen rich blood to the cardiac muscles.
what is a cusp?
proper term for a flap of a valve
where are the coronary artery entrances located and why is that beneficial?
just above the semi-lunar valve
- ensures that the cardiac cells receive the highest concentration of oxygen in the blood
- because the heart is a very active muscle
the heart muscle is ‘myogenic’, what does this mean?
contractions are initiated by the cardiac muscle itself
how does damage/blockage of coronary arteries affect cardiac muscles?
- stops blood flow out of the heart, causing backflow and cardiac muscles to contract- leading to a heart attack
- heart will have no energy to contract since it has no oxygen to partake in respiration (cardiac cells will DIE)
what stops bloodflow from going back into the right atrium?
tricuspid valve
what brings oxygenated blood back from the lungs to the heart?
pulmonary vein
what valve closes when the left ventricle contracts?
bicuspid
what valve opens when the left ventricle contracts?
aortic semilunar valve
what is stage ONE of the cardiac cycle?
ATRIAL SYSTOLE
- the muscles of the atria contract
- pressure inside the atria contracts
- semilunar valves in the venacava and pulmonary vein close
- atrioventricular valves open, allowing blood into ventricles
- lasts abt 0.1 seconds
what is stage TWO of the cardiac cycle?
VENTRICULAR SYSTOLE
- muscles of both ventricles contact
- pressure inside ventricles increase
- atrioventricular valves CLOSE
- semilunar valves OPEN
- blood flows OUT of the heart
- lasts abt 0.3 seconds
what is stage THREE of the cardiac cycle?
DIASTOLE
- pressure in the ventricles decrease
- semilunar valves close
- ALL heart muscles RELAX
blood flows into the atria from venacava and pulmonary vein - pressure remains low inside ventricles and blood fills the ventricles.
name the 4 parts of the electrical control of the cardiac cycle system
- the sinoatrial node
- atrioventricualr node
- budle of his
- purkinji fibres
describe the sinoatrial node
- the initial stimulation for contraction originates here
- located on the top of the right atriuim near the opening of the superior venacava
- basic rhythm of stimulation that determines the beat of the heart
describe the atrioventricular node
- mass of neuromuscular tissue situates in the wall of the atrial septum
- usually stimulated by the contraction which sweeps over the atrial mocardium
describe the bundle of his
conductive tissue down the atrioventricular septum
describe the purkinji fibres
carry contraction impulse from left + right bundle branches from the APEX (bundle of his) to the myocardium (muscular heart tissue)
name the 3 steps of the excitation wave of the heart
- atrial systole
- ventricular systole
- diastole
describe the first step of the excitation wave of the heart (atrial systole)
- SINOATRIAL node sends electrical impulse that spreads over both atria
- both atria contract and become DEPOLARISED
describe the second step of the excitation wave of the heart (ventricular systole)
- atrioventricular node passes a wave of excitation (depolarisation)
- introduces a delay; gives ventricles time to fill with blood before they contract
- wave passes down the septum along the BUNDLE OF HIS and spreads up the wall of ventricles at the apex via the PURKINJI FIBRES causing ventricles to contact
describe the third step of the excitation wave of the heart (diastole)
muscles of the atria & ventricles relax (REPOLARISED) and fill with blood
what is the purpose of the atrioventricular septum
a layer of nonconductive tissue that prevents the wave from crossing to the ventricles.,
how are blood types determined?
the presence or absence of different antigens on the surface of the red blood cells.
what are the two most common blood types?
- ABO
- rhesus
what happens if antibodies bind to antigens on the surface of red blood cells?
the cells agglutinate (lump together) LIFE THREATENING
what is an antigen?
a foreign protein on the surface of a cell that can stimulate an immune response in the body (cause a production of antibodies)
what is an antibody?
proteins caused by leukocytes carried in the blood plasma that bind to antigens.
what are the 4 things that make up the blood?
- erythrocytes
- leokocyte
- thrombocyte
- plasma
what is an erythrocyte?
(red blood cell)
- contain heamoglobin which combines with oxygen in the lungs & delivers to respiring cells
- biconcave shape; increases surface area
- no nucleus; more space for heamoglobin
what is a leokocyte?
- immunity
- phagocytosis
- antibody production
- change shape
- mobile
what are thrombocytes
homostatis- involved in blood clotting
what is plasma
- transports substances around the body
- liquid- easily transport solutes dissolved in water and cells are suspended
what is the order of blood flow through the blood vessels?
heart, arteries, arterioles, capillaries, venules, veins,
name the 3 tissue regions in the walls of blood vessels?
- tunica externa
- tunica media
- tunica intima
the tunica externa
- outer region
- made out of tough collagen which resist overstretching
the tunica media
- middle region
- made of elastic and smooth muscular layer
- contraction of smooth muscle which regulates blood flow and maintain pressure
the tunica intima
- inner most region
- single layer of cells (ENDOTHELIUM) - reduces exchange distances
- smooth to reduce friction
structure of the artery
- LUMEN (space where blood flows)
- ENDOTHELIUM (inner layer) is smooth to reduce friction
- elastic tissue stretches due to high blood pressure as ventricles contract (this recoil helps maintain blood pressure)
- MUSCLE contacts and constricts to narrow the lumen (VASOCONSTRICTION) which can reduce blood flow
- artery wall is thick to withstand high blood pressure
vein structure
- muscle layer is relatively thin (cannot control flow of blood)
- elastic layer is relatively thin because of low pressure in veins
- overall thickness of wall is small
- wide lumen
arterioles structure
- smaller than arteries
- muscular layer to help vasoconstriction to reduce blood flow to capillaries
- elastic layer makes up smaller proportion of wall because blood pressure is lower
capillary structure
- lumen is only wide enough for one red blood cell to pass through at a time
- blood flow is slow enough to allow exchange of substances
- endothelium is is only one cell thick (reduced exchange surfaces)
- have the highest TOTAL cross sectional area of any blood vessel.
