the cardiovascular system Flashcards
The main components of the CV system
blood
blood vessels
the heart
what are the two pathways(parts) of the circulatory system
systematic circulation
pulmonary circulation
where in the body does blood pick up;
oxygen
nutrients
the lungs
GI tract
the heart removes cellular waste for excretion, true or false
true
primary function of the CV system
the transport of materials to and from all parts of the body
in how many directions does blood flow, why?
one direction(uni-directional)
valves in the heart ensure the restriction of the backflow of blood
how is blood pressure affected by distance
BP decreases with increased distance from the heart
by what percentage does BP approximately decrease by from the aorta to the vena cava
90
why does blood pressure fall as it moves through blood vessels away from the heart
Because of friction (fluids& vessels)That friction creates a resistance (that opposes the movement)
myocardium
the muscular tissue of the heart.
what is the heart mainly composed of
the myocardium
where does the vena cava receive blood from
systematic veins
where does the pulmonary vein receive blood from
veins of the lung
where does the aorta send blood to
systematic arteries
the bicuspid valve is aka
mitral valve (left AV valve)
functions of the chordae tendineae
anchoring the valve leaflets
preventing prolapse, coordinating valve movements
functions of the semi-lunar valves
prevents the backflow of blood into the ventricles during ventricular relaxation
functions of the coronary artery
supply the heart muscle (myocardium) with oxygenated blood
nutrient delivery to the heart
pacemaker cells aka
autorhythmic cells
are myocardial cells contractile?
yes
function of the contractile cells
they provide the mechanical force of the heart, thereby leading to contraction
functions of autorhythmic cells
they induce spontaneous action potentials to coordinate contraction
do the autorhythmic cells contribute to the mechanical force of the heart
no they do not
Excitation-Contraction Coupling
the process linking electrical signals to muscle contraction
in which cells should APs be generated for there to be contraction of the heart
myocardial cells and the pacemaker cells.
The heart’s electrical activity is coordinated by specialized cells in the sinoatrial (SA) node, the natural pacemaker of the heart, and is then propagated to the myocardial cells.
outline the processes of the ECC(excitation contraction coupling )
Action Potential Initiation
Opening of Voltage-Gated Ion Channels. These channels allow the influx of calcium ions (Ca²⁺) into the cell.
Calcium ions induce calcium ion release through Ryanodine receptor channels
this causes a calcium ion wave
summed calcium ions sparks creates a calcium signal
Binding of Calcium to Troponin to initiate contraction
relaxation occurs when calcium ions unbind from troponin
calcium ions pumped back into the sarcoplasmic reticulum for storage
calcium ions are exchanged with sodium ions by the NCX transporter
Na+ gradient maintained by Na+/ K+ pump
phases of action potentials in the myocardial cells(in order)
phase 4
phase 0
phase 1
phase 2
phase 3
phase 4
what happens in phase 4 of APs in myocardial cells
resting membrane potential
what happens in phase 0 of APs in myocardial cells
Depolarization
what happens in phase 1 of APs in myocardial cells
initial repolarization
what happens in phase 2 of APs in myocardial cells
This is the plateau phase on the graph.
two events happen;
decrease in K+ permeability(smaller outward current)
Ca+ inward current
what happens in phase 3 of APs in myocardial cells
Repolarization.
Ca+ channels close and K+ channels opens (again).Outward K+ current.
the mechanism of isovolumetric contraction in the heart
volume changes during isovolumetric contraction
The ventricles contract, generating pressure.
The AV valves close to prevent blood from flowing back into the atria.
The semilunar valves are still closed at this point.
Volume Changes: The volume of blood in the ventricles remains constant during
the phases of action potentials in pacemaker cells in order
phase 4
phase 0
phase 3
phase 4
mechanism of isovolumetric relaxation in the heart
volume changes during isovolumetric relaxation
The ventricles relax.
The semilunar valves close to prevent blood from flowing back into the ventricles.
The AV valves remain closed.
The volume of blood in the ventricles still remains constant during isovolumetric relaxation because no blood is entering the ventricles from the atria yet.
what happens in phase 0 of APs in pacemaker cells
unstable resting potential
what happens in phase 0 of APs in pacemaker cells
depolarization
what happens in phase 3 of APs in pacemaker cells
repolarization
what happens in phase 4 of APs in pacemaker cells
pacemaker potential:
Sodium (Na⁺) and calcium (Ca²⁺) channels open, allowing a slow influx of positive ions, leading to the gradual depolarization
do pacemaker cells have a stable resting potential
no.
they instead exhibit a slow, spontaneous depolarization during diastole
End Diastolic volume
End systolic volume
EDV refers to the volume of blood in the ventricles at the end of diastole, which is the relaxation phase of the cardiac cycle
ESV refers to the volume of blood in the ventricles at the end of systole, which is the contraction phase of the cardiac cycle.
User
to decrease the bodies CO2 levels, should respiration be at a higher or lower rate
increase respiration rate
all blood vessels except capillaries have three tissue layers, name these layers
Inner layer: Tunica interna(intima)
Middle layer: Tunica media
Outer layer: tunica externa
70% of our blood volume is on the venous side, true or false
true
composition of the tunica interna of the blood vessels and their roles in the vessels
endothelial cells:control contractility
basement membrane: separates the tunica interna from the tunica media
internal elastic lamina: allows distension when high pressure blood is ejected from the ventricles
composition of the tunica media in blood vessels and their functions
this layer is usally the thickest in the vessels
smooth muscle cells:sets the vascular tone by maintaining partial contraction of the vessel
gap junctions: AP transmission
elastin(elastic fibre cells)
composition of the tunica externa
Collagen
Elastin fibre
Vasa vasorum (vessels of the vessel): capillaries in large arteries and veins thatprovide oxygen and nutrients to the cells inthe tunica externa
involves blood transport, etc…
functions of arterioles
carry blood from arteries to capillaries.
Also help to maintain blood pressure
which blood vessel is responsible for most of peripheral resistance
arterioles
below is a list of the constituents of the different blood vessels, for each constituent, name all the vessels that possesses it
Endothelium:
Elastic tissue:
Smooth muscle:
Fibrous tissue:
arteries, arterioles, capillaries, venules, veins
arteries and veins
arteries, arterioles and veins
arteries, venules and veins
which blood vessels regulate the MAP
arteries
function of capillaries
Microscopic vessels that connect arterioles to venules.
Control blood distribution to organs.
Monolayer- Exchange Nutrients
funtions of venules
drain blood from capillaries into veins
the most abundant protein in the blood
albumin
the most abundant cells in the body
erythrocytes(RBCs)
features of RBCs
Concave shaped cells
Anucleated(lacks a nucleus)
Contain Haemoglobin
Account for 40-45% of blood volume
lifespan of RBCs in humans
Last 120 days then broken down primarily in the spleen via haemolysis. they are then recycled by macrophages
how many subunits does haemoglobin comprise of
4
2 alpha and 2 beta subunits
what does each subunit in haemoglobin contain
each haem group can bind to an oxygen
an ironatom bound to a haem group.
has to do with affinity
what is meant when we say haemoglobin is an a:
tensed form
relaxed form
Tense(deoxygenated) form; low affinity for oxygen
relaxed(oxygenated) form; high affinity for oxygen
in which three forms are carbon dioxide transported in the blood
in bicarbonate form
in solution(dissolved Co2)
when bound to Hb(Carbaminohemoglobin)
