Circulatory System Quiz Flashcards
How does the heart muscle appear under a microscope
striated
whats the myogenic heart muscle
ability of the muscle to contract without external nerve stimulation
What is an example of nervous stimuli to increase heart rate?
fear, excitement, tension
what’s an example of physical stimuli to increase heart rate
exercise
whats an example of chemical stimuli to increase heart rate
carbon dioxide, nicotine, caffeine, alcohol, hormones
whats the main nervous regulating centre of heart rate called
medulla oblongata
what do the 2 pairs of nerves leaving the medulla oblongata
one pair increases heart rate, the other pair slows heart rate down
where are the stimulatory nerve fibers located
in the spinal cord
where are the inhibitory nerves located
in vagus nerve of brain
what is the heart rate set by
sinoatrial node (SA node)
What is the sinoatrial node
a bundle of speicalized nerves located when venae cavae enter right atrium that acts as a pacemaker for the heart
where are nerve impulses from the ‘pacemaker’ of the heart carried
to the atrioventricular node
where are nerve impulses from the ‘pacemaker’ of the heart carried
to the atrioventricular node (AV node)
where is the atrioventricular node located
spetum of the heart
what does the AV node do
it serves as a conductor passing nerve impulses along special tracts through the dividing septum toward the ventricles
where do the impulses go from the AV node
bundle of his
whats the bundle of his
special tissues that runs down the septum to the apex of the heart
what’s the order in how nerve impulses travel through the heart
SA node –> AV node –> bundle of his –> purkinje fibres
where do the impulses go after the bundle of his
off to the pukinge fibres
what do the purkinje fibres do
conduct impulses into the muscular walls of the ventricles
where do the ventricular contractions begin
at the bottom of the ventricles and then spread upwards
What are contractions immediately followed by and why
Relaxation; because the heart muscle cannot sustain a contraction for a long period of time
how does the AV node ensure that the ventricles contract a fraction of a second after the atria
through the time required to stimulate the node
what causes heart rate to increase
impulses from vena cava
what causes heart rate centre to decrease heart rate
impulses from aorta or carotid arteries
how does an artifical pacemaker work
electrode emits electrical impulses at timed intervals that can speed up a heart rate or correct an erratic heartbeat
whats an electrocardiogram
device which measures electrical fields in the heart
what does the p wave of an ECG show
atrial contraction
what does the QRS spike of an ECG show
records ventricular contraction
What does the t wave of an ECG mean
Signals that the ventricles have contracted
how do blood cells move through capillaries
in single file
what does blood have to do in capillarie beds and what does it do
it has to slow down which enhacnes nutrient, gas and waste exchange
whats the typical amount of lbood in the body
5-7 litres
what is the lining of blood vessels called
endothielia cells
why are capillaries so thin
helps to enhance absorption
what do precapillary sphincters do
allow or prevent passage of blood into a capillary bed so that the blood can be directed to the specific beds as needed
whats a capillarie bed
an enormous number of capillaries
what are the 5 types of capillarie exchange
diffusion, osmosis, active transport, ameboid movement, and hydrostatic pressure
whats capillarie exchange
transfer of substances between the blood and extracellular fluid (ECF)
whats capillary exchange
transfer of substances between teh blood and extra cellular fluid (ECF)
whats emeboid movment
when white blood cells squeeze out of capillary pores
whats hydrostatic pressure
force that moves fluids thorugh pipes
what does hydrostatic pressure do in the circulatory system
makes it so that blood pressure is due to the force of the heart
where is hydrostatic pressure the greatest in a capillary bed
arteriole end
where is hydrostatic pressure the least in a capillary bed
at the venule end
What does hydrostatic pressure assist with
speeding up the transfer of materials in capillary exchange
what are the 2 main factors that effect blood pressure
cardiac output and the resistance of arterial blood vessels
what is cardiac output
the amount of. blood pumper by the ventricles per minute
whats stroke volume determined by
the size of the heart; fitness level/strength of the heart
whats stroke volume
the amount of blood pumped to the body with each beat of the heart
what 2 factors effect cardiac output
heart rate and stroke volume
what 3 factors affect resistance of arterial blood vessels
blood viscosity, diameter and elasticity of blood vessels
what is vasoconstriction
narrowing of the blood vessels, increasing blood pressure
whats vasodilation
enlargement of blood vessels which decreases blood pressure
What is vasoconstriction under
sympathetic control
What is vasodilation under
parasympathetic system control
What are some other factors that can influence blood pressure
stretch receptor stimulation, precapillary sphincter regulation, amount of blood, hormonal control
what is the pulse
surge of blood at each ventricular contraction through muscular, elastic arterial walls
what does systolic pressure represnet
when the ventricles ocntract
what does diastolic pressure represent
when ventricles relaz and are filling
why is diastolic pressure so critical
it indicates the amount of rest a heart will get
how long does each cardiac cycle roughly last
around 0.8 secondons
whats hypertension
when arteriole blood pressure is above average and involves a sustained systolic pressure or diastolic pressure greater then the average range
what does being overwheight do to blodd vessels
decreases internal diameter which can increase risk of heart problems
what happens during shock
the heart beats faster and fast, decreasing cardiac output and causing the relaxation of ventricles to become shorter, resulting in less blood filling the ventricles and the stroke volume lowering
whats coronary artery disease
disease of the arteries surrounding the heat
what is atherosclerosis
deposition of fatty compounds on the inner lining of the coronary arterys
what is angina pectoris
an episode of chest pain due to a temporary difference between the supply and demand of oxygen to the heart muscle
whats an arrhuthmia
an abnoraml heart rythm
whats a heart murmur
when an extra sound is heard between normal heart sounds
