cardiovascular unit 6 lessons Flashcards
stoke volume equation
stroke volume= EDS- ESV
EDS- end diastolic volume
volume of blood in ventricles at the end of diastole
just BEFORE they contract
ESV- end systolic volume
volume of blood in ventricles at the end of systole
just AFTER contracting
End diastolic volume
what controls stroke volume
lesson 3.
- ANS
Sympathetic (flight or flight)
- release EPINEPHRINE or norepinephrine and bind to adrenergic receptors
- increase ca2+ permeability, with increase stroke volume and increase muscle contraction
Parasympathetic (rest and digest)
- slow down heart beat
- release acetylcholine, bind to muscarinic receptors
- ca2+ permeability decreases, with decrease stroke volume and decrease muscle contraction
2.PRELOAD on heart
- how much blood is in the heart before contracting
“load”- before - EDV “end diastolic volume”
the larger the load is the more stretch there is on ventricles, and therefore a larger contraction (bigger stroke volume occurs)
stroke volume
cardiac output
is during one systolic contraction
cardiac output-
during one minute of ventricular contractions
how does the SNS effects blood vessels
affects the SA node (pacemaker) and ventricular muscle
innervates blood vessels
- squeezes the viens,
which increases venous return, EDV, SV, co
what are fenestrations
-pore found within endothelial cells
- which allow movement of small molecules
fileration vs absorption
filtration- movement OUT of a capillary
absorption- movement IN to a capillary
what are the two circulatory systems
pulmonary- blood vessels only to and from the heart (15%)
systemic- cary blood to the rest of the body (85%)
- 70% of blood is found in the viens
what are the main functions of the nervous system
- transport oxygen and nutrients to the body
- removes carbon dioxide and waste products from the tissues
- regulate body temperature and ph - acidity of blood
- transports and distributes hormones and other substances throughout the body
what is the difference between contractile and conductive cells in the heart
contractile cells-
causing heart to beat and contract
conductive-
act like a neuron
establishes heart rate
communicates throughout different cells
what are myocardial cells composed of
- thick and thin filaments
- lots of mitochondria, heart always needs an abundance of ATP
- branched cells
intercalated discs:
- gap junctions , allow cells to communicate through ion channels, and proteins connexions
- desmosomes, anchor end of cardiac muscle, so cells can’t pull apart during contraction
contraction difference in nodel cell vs neuron action potential
neuron- RMP of -70
- action potential stimulated at -55
- four milliseconds
nodal cell- RMP- no stable resting membrane potential
- lowest is -60
-threshold is -40
- very kittle k+ leak, that is why doesn’t get as negative
- a lot slower 0.8 seconds
compare
skeletal muscle- myocardial cell- smooth muscle
what does an ECG measure
- sum of all electrical impulses in the heart
- fluids conduct electricity well
-recorded by surface electrodes
p- atrial depolarization
QRS- ventricular depolarization
T- ventricular depolarization
how does parasympathetic innervation effect heart rate
- Ach binds to MUSCANNIC receptor
- lows down
less na+/ ca 2+ into cell
more k+ leaving cell
rest and digest- to slow down heart rate
how does sympathetic innervation effect heart rate
- increase ca/na in cell
-decrease the k leaking out - want greater chance of action potential
- increase slope of action potential- reach action potential quicker
pre load effect on the heart
EDV- the amount of blood in the heart after contraction
- greater force on heart, bigger stretch, harder and more forceful contraction - bigger stroke volume
the effect of moving on venous return
when running for example
- your contracting muscles, squeezes blood in veins back to heart
- increase EDV
- so it increases stroke volume and co
what is the difference is structure and function between arteries and arterioles?
artery- distribution vessel
- “shock absorbers”
- high blood pressure
- little resistance
- elastic fibres
arterioles-
resistance fibers
- vasoconstriction and vasodilation
-smooth muscle
- thick walls
- pinch happens here
cappilary
- very thin walls
- one epithelial cell thick
-great for diffusion
continuous capillary vs fenestrated
fenestrated
- holes to allow larger molecules pass through
what is the middle layer of the blood vessel called and what is it made up of
called: tunica media
smooth muscle
elastic tissue
if net filtration is positive vs negative
positive- filtration
negative- reabsorption
veins purpose
capacitance vessel
very low blood pressure, blood reserve
very thin walls
some elastic tissue and smooth muscle
what are the three mechanisms used to regulate blood flow
- local (intrinsic)
- environment in tissues
2.humoral (extrinsic)
- substances in blood
- neural (extrinsic)
- nervous system
explain local mechanism to regulate blood flow
- myogenic theory
- muscle stretch
- increase in BP
- stretches arterioles walls (smooth muscle) detect the stretch, contraction in smooth muscle of arteriole walls, vasoconstriction, decreases blood flow after constriction
to protect the cappilarries and maintain normal blood flow
- metabolic theory
- change in metabolism
and tissue conditions
o2 decrease
co2 increase
H+ increase, in acidity, decrease in Ph
temperature increase
