Chapter 14 (The Heart) Flashcards
Systemic Circulation
Vessels that carry blood away from the left side of the heart, to the tissues, and back to the right heart
Includes Arteries and Veins
Arteries and Veins
A - Carry Oxygenated blood from left ventricles
V - Carry Deoxygenated blood back to the right atrium
Pulminary Circulation
Goes from right side of heart to left side
Includes blood vessels that go:
From the right ventricle to the lungs: Pulmonary Arteries.
From the lungs to the left atrium: Pulmonary Veins.
Heart Position
Lies in the center of the thorax
Primary function of CVS
CVS= Cardiovascular system
Transport of nutrients, water, gases, wastes, and chemical signals to and from all parts of the body.
Is CVS a closed or open system?
Closed loop system
4 chambers of the heart
2 atria, 2 ventricles
CVS
Includes, Transport, Waste elimination
Heart (pump), Blood (fluid), Blood vessels including capillaries (tubes)
Transports materials throughout the body
- From external environment: nutrients, water, and gases
- Materials between cells: hormones, immune cells, antibodies
“Waste” eliminated by cells - CO2, heat, metabolic waste
Waste - nothing is really weight when thinking about mass balance and ho
How does blood flow?
Ohm’s Law
Flow = Δ Pressure / Resistance
The Physiological Equivalent:
Q = MAP/R total peripheral
R = Total resistance in the
vessels
Need to me memorized & number
MAP = Q x R total peripheral
MAP = NET driving pressure = ΔP = P1-P2
Q = flow due to central factors = (HR x SV)
R = to resistance due to peripheral factors = diameter or r4
Adjusted to maintain homeostasis
Q increases, R stays the same, What will happen to MAP?
It will increase
Resistance
inversely proportional to resistance due to resistance
Flow = 1/R
Small changes in resistance lead to big impacts for flow
increase in resistance = decreased flow
Resistence depends on
R=resistance
r=radius
Length of the tube (L) - R=L
Radius of tube - R = 1/r4
Viscosity (n) of the fluid - R=n
R increases as L and η increase, and r decreases.
Radius
Physiolgically regulated
Vasodilation - r increases, R decreases, blood flow increases
Vasoconstriction - r decreases, R increases, blood flow decreases
… Has greatest effect on resistance
Blood flow
Down a pressure gradient (ΔP) (proportional to fluid flow)
Highest pressure (aorta) to lower pressure (vena cava & pulmonary veins)
Driving pressure
Pressure of blood created when ventricles contract
Flow rate
Volume of blood that passes per unit of time
Dialation and pressure relationship
dialation increase = pressure decreases
Dialation decreases = pressure increases
Pressure gradient
Difference in pressure b/w 2 regions
Pressure gradient
Difference in pressure b/w 2 regions
What are the 2 movements of fluid
Dynamic (kinetic energy) and lateral (hydrostatic pressure)
Hydrostatic pressure
: pressure exerted (in all directions) by a fluid not in motion
Look at slide 24
Math
Layers of the heart
Endocardium (Inner) - Endothelial cells
Myocardium (middle) - Cardiac muscles
Epicardium (outer) - External membrane (also attached to pericardial sac)
Paracardium
Mebranous sac encasing heart, fused to diaphram, holds paracardial fluid
pericardial fluid
lubricates and allows the heart (myocardium) to operate in a friction free environment.
Ventricular Wall Thickness
Which one and why
Left is thicker b/c it pumps blood to the whole body, so it need the increased pressure
Endocariogram
Provides information on:
The size and shape of the heart,
Its pumping strength, and
The location and extent of any damage.
useful for assessing diseases of the heart valves and cardiac hypertrophy.
Myocardial Muscle
- Branched
- attached by intercalated disks
- have a single nucleus
Action potential shape of authorythmic and contractile cells
authorythmic - has ine sharp point
contractile - looks like a lowercase N
what allows the heart to squeeze the blood up?
the spiral muscle arrangement (produce a wringing motion)
Desmosomes and Gap junctions
Both found in Cadiac muscle
D: Strong protein that surrounds sarcomeres and bind neighbouring sarcomeres.
Allow force to be transferred.
GJ: Provide electrical connection.
Electrical signals are rapidly transmitted via these protein pores providing the basis for SYNCHRONOUS CONTRACTION.
allows for rapid cell depolarization
Cardiac muscles Structures
1) Single nucleus per fiber.
2) Distinctive short rectangular shape.
- Are smaller compared to skeletal muscle
3) Spontaneously Contract
- Pacemaker cells within the sinoatrial (SA) node control rate
4) Branch and join neighboring cardiac cells through intercalated disks, which are comprised of
- Desmosomes hold cells together
- Gap Junctions move ions
5) Ca2+ is sequestered in the sarcoplasmic reticulum (SR) as in skeletal muscle but SR is less voluminous.
- Cardiac muscle depends partly on extracellular Ca2+.
6) t-tubular network is more extensive than skeletal muscle
- Allows rapid, synchronous excitation-contraction coupling.
7) Large volume of mitochondria (~ 1/3rd of volume).
- This feature is due to the dependence of the heart on aerobic ATP production.
Cardiac muscles Structures
1) Single nucleus per fiber.
2) Distinctive short rectangular shape.
- Are smaller compared to skeletal muscle
3) Spontaneously Contract
- Pacemaker cells within the sinoatrial (SA) node control rate
4) Branch and join neighboring cardiac cells through intercalated disks, which are comprised of
- Desmosomes hold cells together
- Gap Junctions move ions
5) Ca2+ is sequestered in the sarcoplasmic reticulum (SR) as in skeletal muscle but SR is less voluminous.
- Cardiac muscle depends partly on extracellular Ca2+.
6) t-tubular network is more extensive than skeletal muscle
- Allows rapid, synchronous excitation-contraction coupling.
7) Large volume of mitochondria (~ 1/3rd of volume).
- This feature is due to the dependence of the heart on aerobic ATP production.
What ensures one way flow in the heart
The 2 sets of valves
Mitral/bicuspid valve
Tricuspid valve
Aortic semilunar valve
Pulminary semilunar valve
how does Cardiac muscle differ from skeletal muscle?
1)Smaller and have a single nucleus per fiber
2)Branch and join neighboring cells through intercalated disks
3)Gap junctions
4)T-tubules are larger and branch
5)Sarcoplasmic reticulum is smaller
6)Mitochondria occupy one-third of cell volume
What is the type of most cardiac muscle?
striated muscle
Contractile cells
contain
have striated fibers in sarcomeres
Authorythmic cells
Where signal for contraction originates
Noncontractile myocardium
Not orginized sarcomeres
Action potential of a cardiac contractile cell
0- Na+ channels open
1- Na+ channels close
2- Ca2+ channels open; fast K+ channels close
3- Ca2+ channels close; slow K+ channels open
4- Resting potential
EC coupling in cardiac muscles Steps
14.1 - 55-58
What is determined by how much Ca+ binds to troponin?
The number of active crossbridges
What is determined by how much Ca+ binds to troponin?
The number of active crossbridges
Action potential Authorythmic cells
- unstable membrane potential
- membrane potential never rests
- Called pacemaker potential
Table 14.3 Comparison of Action Potentials in Cardiac and Skeletal Muscle
slide 68
what causes steep depolarization in authorythmic cells?
Caused by Ca+ influx
where do action potentials start in the heart
Pacemaker cells
Pacemaker potential
When the autorythmic cells depolarize on it’s own
Funny Na+ channels open spontaneously at
-60mV
