Download Entering and Exiting the blood

S1
Secretion
Reabsorption
Filtration
S2
Circulatory System Circulates
•
•
•
•
•
Nutrients: glucose, amino acids, fatty acids, ketones, etc
Wastes:
Hormones: bound & free
Gases: CO2 and O2
Formed Elements: Cells and Cell Fragments
– Erythrocytes, Leukocytes, Thrombocytes = Platelets
Other roles of the Cardiovascular System
Thermoregulation
Blood Clotting
Reproduction (ex: penile erection)
S3
Blood volume ~ 5 liters
Figure 12.01
Serum = plasma – clotting factors
Entering and Exiting the blood
Components……
EPO and
“The Scoop on Tissie”
Discontinuous capillaries in
bone marrow, spleen, &
liver permit erythrocytes to
enter and exit blood.
Formed
elements
Hct = percentage
of blood volume
occupied by RBCs
Anemia
Blood doping & erythropoietin (hormone that
stimulates erythrocyte production in bone
marrow) to increase hematocrit
S4
Fig. 12.02
Arteries..away from heart
Veins..return to heart
Resting Cardiac Output = 5L/min
for each side!
When left heart
can’t pump all the
blood it receives
from pulmonary
circuit (due to high
aortic pressure
and/or damage to
left ventricle) blood
accumulates in
pulmonary circuit.
This is congestive
heart failure.
Symptom:
shortness of
breath.
Regional blood flow
determined by arteries
and arterioles.
S5
Figure 12.04
CO = 5L/min
for each circuit
Up to 35 L/min
in strenuous
exercise
S6
Pulmonary circuit
CO = 5 liters/min
Arterial Blood Pressure
Systemic Circuit
Exchange Vessels
What’s
missing?
CO = 5 liters/min
Recall Portal Systems!
Resistance Vessels
Microcirculation
Capacitance vessels
S7
Pulmonary circuit
Pressure gradients
makes fluids move.
Moving fluids flow,
but flow is limited by
resistance.
Resistance creates
pressure.
Systemic Circuit
Arterioles establish Mean Arterial Pressure
S8
Radius of arterioles
regulates Q to organs
F=Q=ΔP/R
Flow = Pressure gradient/Resistance
from Ohm’s Law (V=IR)
Double radius … 16x flow
R=
8Lη/πr4
Half radius….1/16th flow
Q= ΔP πr4
8Lη
Poiseulle’s equation
Smooth muscles
determine radius
S 14
Mean Arterial Pressure = Cardiac Output x Total Peripheral Resistance
MAP = CO x TPR
MAP = (HR x SV) x TPR
S1
Cardiac Output = Heart Rate X Stroke Volume
What regulates
heart rate?
What regulates
Stroke Volume?
CO = HR x SV
5L/min = 72 beat/min x 70 ml/beat
The Cardiac Cycle animation
Problems with valves:
Heart murmurs ≠ heart sounds
….Stenosis (narrowing) →Heart Murmurs (turbulent flow past a constriction)
Figure 12.07
note: origin of neonatal heat murmurs (foramen ovale)
….Prolapse (eversion) allows backflow (also generates murmurs)
S4
Tricuspid
Heart sounds
produced by
valve closings
Semilunar
Valves
Bicuspid
=Mitral
Animation
S3
Cardiac Myofiber
action potential
Plateau phase
Figure 12.13
Long refractory
period prevents
summation in
cardiac
myofibers
Cardiac
Myofiber
S4
Figure 12.11
S5
SA node cells
do not have stable
resting membrane
potential,
spontaneously
produce AP,
are Pacemaker cells
S5
Cardiac Pacemaker
action potential
Figure 12.14
Ectopic
Pacemaker
Pacemaker
Cells in
Conducting
System:
SA Node and
Bundle of His
Locations
other than
SA Node
These cells
set the
rhythm &
control
Heart Rate.
S 15
Figure 12.22
Intrinsic Rate = 100 beat/min
2 effects of Parasymp:
hyperpolarization &
slower depolarization
S6
Figure 12.23
NE
Beta-adrenergic receptors
Effect of “Beta blockers”
EPI
ACh
mAChR
Effect of atropine
S7
What prevents the AP from being conducted from ventricles back to atria?
Fibrous connective tissue between atria and ventricles prevents the
conduction of action potential. Only route is via AV node, bundle of His,
bundle branches, Purkinje fibers, and to ventriclular myofibers.
S8
“Sis-toe-lee”
1st Heart Sound =
Closure of
Atrioventricular
(AV) valves at
beginning of
Ventricular
Systole
“die-ass-toe-lee”
2nd Heart Sound =
Closure of Semilunar
valves at beginning
of Ventricular
Diastole
S9
Figure 12.20
Systolic
Diastolic
Atrial Fibrillation
Stroke Volume
Ejection Fraction = SV/EDV
Ventricular
Fibrillation &
Defibrillation
Animation
S 10
Events are same for Cardiac Cycle for Right Side
of Heart; only difference is lower systolic pressures
in right atrium and right ventricle.
S1
So far, we’ve dealt with the factors that
control Cardiac Output by changing
heart rate.
3
CO = HR x SV
2
+ sympathetic
- parasympathetic
1
5L/min = 72 beat/min x 70 ml/beat
35L/min = ? beat/min x ? ml/beat
S2
Figure 12.20
Stroke Volume
Animation
S3
Frank-Starling Law of the Heart
Does not depend on hormones or nerves
Assures that the heart adjusts its output based on VENOUS RETURN
Ventricular Function Curve
Ways to enhance
Venous Return:
1) muscle contractions
2) “respiratory pump”
3) venoconstriction
FS LoH = SV is proportional to EDV
↑VR→ ↑EDV → ↑SV
S4
Length-tension “curve” for Cardiac muscle
Fig. 09.21
High EDV
Low EDV
Overinflation of
ventricles leads to less
effective pumping
S5
Overinflation of
ventricles results in
reduction in stroke
volume
Treatments?
…..diuretics
S6
NE from Symp postganglionics &
EPI from Adrenal medulla acting
via B-adrenergic receptors on
cardiac myofibers.
Contractility
Increase Ejection Fraction
Note: cardiac myofibers
NOT innervated by
parasympathetic division
S7
3 Effects of
Sympathetic
Stimulation
1: Increase rate of contraction
2: Increase peak tension
3: Decrease twitch duration
Why should the
contraction be shorter?
Afterload is analogous to trying to pump more air into a tire that is already fully inflated
(heart contracting to overcome diastolic pressure.)
S9
High blood pressure increases the workload of the heart….. Cardiac
hypertrophy….increase chance of irregular conduction of AP through heart
Hypertrophic cardiomyopathy
S8
Summary: Control of Stroke Volume
FS LoH
• End diastolic volume (preload)
• Contractility (strength of ventricular
contraction due to adrenergic stimulation)
• Pressure in arteries that must be
overcome = Afterload
S 11
Factors that control Cardiac Output by
changing heart rate and stroke volume.
Afterload (MAP)
CO = HR x SV
EDV (FSLoH)
+ sympathetic
- parasympathetic
contractility
5L/min = 72 beat/min x 70 ml/beat
35L/min = ? beat/min x ? ml/beat
Summary of Factors that Regulate Cardiac Output
S 12
Fig. 12.28
Even persons with heart
transplants can adjust CO
in the absence of
innervation of heart.
S 13
Heart is pump that generates
pressure gradient.
Blood flows through vessels,
which have resistance.
Arterioles have greatest
resistance and create
“backpressure” in the arteries
and aorta.
Mean Arterial Pressure = diastolic +1/3(systolic – diastolic)
= 70 + 1/3(120-70)
= 70 + 17
= 87 mm Hg