OC3 - cardiovascular system Flashcards
what are the three layers of the heart wall?
epicardium
myocardium - cardiac muscle
endocardium
what is the pericardium?
the heart is surrounded by the pericardium
a loose fitting membrane which holds the heart in place
a double-layered sac covering the heart
the outer layer anchors the heart in the chest
the inner layer is attached to the heart wall
lubricating fluid in pericardial space reduces friction.
what is the structure of the heart?
diagram…
4 chambers
valves
what are the four chambers of the heart?
left and right atria - separated by septum
left and right ventricle - separated by intraventricular septum
what is the function of valves in the heart?
prevent back flow of blood
what is the composition of the valves in the heart?
composed of connective tissue - tendon like cords
held in place by muscles
what are the types of valves in the heart?
semilunar
atrioventricular
what are the semilunar valves?
pulmonary valve
aortic valve
the tendinous cords of the semilunar valves prevent the cusps of the valve opening to prevent backwards blood flow from the arteries to the ventricles.
what are the atrioventricular valves?
tricuspid valve - right atrium to right ventricle
bicuspid (mitral) valve - left atrium to left ventricle
the tendinous cords of the AV valves prevent the cusps of the valve opening to allow flow of blood from the ventricles to the atria.
what is the circulation route?
vena cava - right atrium - right ventricle - pulmonary artery - lungs - pulmonary vein - left atrium - left ventricle - aorta
what is the cardiac cycle?
the heart beat is a cycle of cardiac muscle contraction and relaxation.
what is cardiac muscle contraction called?
systole
what is cardiac muscle relaxation called?
diastole
what is atrial systole?
the atria simultaneously contract and send blood to the ventricles
what is ventricular systole?
the ventricles contract forcing semilunar valves to open and send blood into pulmonary artery (R) and aorta (L)
what is complete cardiac diastole?
occurs after systole, the chambers of the heart relax, allowing the blood to return to atria
what are the circulation types?
pulmonary circulation
systemic circulation
what is pulmonary circulation?
the loop of blood from the heart to the lungs
blood is carried from the heart to the lungs by the pulmonary artery and is returned to the heart by the pulmonary vein
blood gets oxygenated
what is systemic circulation?
the loop of blood from the heart to the body
blood is carried from the heart in the aorta, and travels around numerous vessels to be returned to the heart in the vena cava
to provide the body with oxygenated blood.
what are the components of blood?
plasma (55%)
cells (45%)
what is the composition of blood?
plasma - water, proteins, nutrients, hormones
buffy coat - white blood cells, platelets
hematocrit - red blood cells
what are the components of plasma?
water - 91.5%
solutes - 1.5%
proteins - 7%
what are the solutes found in plasma?
electrolytes - Na+, K+
nutrients - amino acids, glucose, fatty acids, glycerole
gases - O2, CO2, N2
what are the protein found in plasma?
albumins
globulins
fibrinogen
what are the cell types in blood?
erythrocytes - red blood cells
leucocytes - white blood cells
thrombocytes - platelets
what is the function of blood?
transportation of oxygen nutrients and hormones
regulation of body temperature
protection against infections by white blood cells
what is haemoglobin?
a protein molecule that can bind four oxygen molecules per haemoglobin molecule
contains an iron-containing haem group that gives red blood cells their colour.
erythrocytes structure
biconcave disc
gives a larger surface area to volume ration
efficient for gas exchange
flexible - can fit through capillaries
carry haemoglobin which carries oxygen (x4)
have no organelles - increases space in the cytoplasm for haemoglobin
blood groups
red blood cells have glycolipids/glycoproteins on their surface which determines blood groups
what are the types of lymphocytes?
T cells - thymus
B cells - lymph nodes
what are thrombocytes (platelets)?
formed from small pieces of cytoplasm shed from large cells called megakaryocytes
involved in blood vessel repair and the clotting mechanism.
what is the clotting cascade?
diagram
platelets release thromboplastin when injured, this converts prothrombin to thrombin which eventually converts soluble fibrinogen to insoluble fibrin forming a sticky web to trap other blood cells - to form a clot - haemostasis.
what is cardiac output?
the volume of blood pumped out of each ventricle per minute (l/min, or ml/min)
determined by the heart rate and the stroke volume
influenced by blood pressure and resistance
CO = HR x SV
CO = MAP/TPR
what is the relationship between cardiac output and blood pressure
⬆CO = ⬆BP (during exercise)
what is stroke volume?
the volume of blood ejected by each ventricle per beat
what is mean arterial blood pressure (MAP)?
average blood pressure within the body
the pressure exerted on the wall of a blood vessel
what is total peripheral resistance (TPR)?
the force of friction as blood moves along the vessels
what is blood pressure?
the pressure exerted on the wall of a blood vessel
highest in the aorta, lowest in the vena cava
what factors increase blood pressure?
increase in cardiac output
increase in blood volume
increase in peripheral resistance
what is peripheral resistance?
the impedance of blood flow
what factors influence peripheral resistance?
blood viscosity - ⬆viscosity = ⬆resistance = ⬆BP
blood vessel length - ⬆length = ⬆ resistance
blood vessel radius - ⬇radius = ⬆ resistance
vasodilation ⬇resistance = ⬆blood flow
vasoconstriction ⬆ resistance = ⬇blood flow
what is the influence of an increase in fitness?
same cardiac output with a lower heart rate
increased stroke volume - myocardial contractions are more forceful and efficient due to increased muscular tome of the myocardium
lower resting heart rate
what are the vessels in the cardiovascular system?
arteries
veins
capillaries
arterioles
venules
what are arteries?
carry blood at high pressure away from the heart
they are elastic
change diameter by muscle contraction - vasodilation and vasoconstriction
maintain blood pressure
have thick walls as there is a high blood pressure exerted on them
have a large internal diameter
inner wall is very smooth to limit plaque build-up
what are veins?
carry blood at low pressure back to the heart against the force of gravity
contain valves to prevent the back flow of blood this is aided by the action of skeletal muscle.
what are capillaries?
have very thin walls - one cell thick
near every tissue cell
involved in gas and nutrient exchange - drop off oxygen delivered from heart by arteries, and, pick up CO2 and send it to the hear via veins
connect arteries and veinsw
what are arterioles?
small arteries
undergo vasoconstriction/dilation so regulate blood flow into the capillaries
affect blood pressure
what are venules?
very small veins
hepatic portal circulation
diagram
what is the conduction system of the heart?
Sinoatrial node undergoes spontaneous electrical activity generating action potentials which spread through the myocardial cells of the right and left atria causing a slight (?) contraction of the atria. The action potential then reaches the atrioventricular node causing a complete (?) contraction of the atria, pushing blood from the atria to the ventricles through the atrioventricular valves.
The signal then passes down the bundle of His which divides into right and left bundles before passing the signal to the purkinje fibres where it is conducted through the ventricles causing contraction of the ventricles pushing blood from the ventricles to the pulmonary artery (R) and aorta (L) through the semilunar valves.
what is the autonomic control of heart rate?
medulla of the brain contains 2 groups of neurones which control heart rate:
CAC - cardioaccelaratory centre - sympathetic fibres - increase heart rate
CIC - cardioinhibitory centre - parasympathetic fibres - decreases heart rate.
what is the cardioaccelaratory centre?
CAC in medulla has sympathetic fibres which release noradrenaline and innervates the sinoatrial node, atrioventricular node and the myocardium.
causes an increase in heart rate and the strength of contraction
what is the cardioinhibitory centre?
CIC in medulla has parasympathetic fibres which release acetylcholine and use the vagus nerve to innervate the sinoatrial node and the atrioventricular node
causes a decrease in heart rate and the strength of contraction.
