Transcript cardiovascular4

For sophomores and juniors interested
in medical school at:
• A visit by Dr. Jim Stallworth and other guests from USC School
of Medicine in Columbia, SC.
• In RMSC 122 (The Pit) starting at 6:30pm, Tuesday Nov 13th.
• Presentation and discussion on admissions and opportunities.
Abstracts and Test 2
• Earn up to 5 points for Test # 2 based on
topics of Frog Heart Lab:
– Regulation of pacemaker cells by
temperature, hormones, neurotransmitters,
antagonists
– Heart block: 1st, 2nd, and 3rd degree
– The conducting system
– Strategies for prolonging survival of in vitro
organs
Cardiac Cycle Animation
1QQ #25 for 10:30
Write the number of the one you choose to answer.
1. Which is more serious and why: atrial
fibrillation or ventricular fibrillation?
2. Explain the Frank-Starling Law of the
Heart in terms of what happens in cardiac
myofiber sarcomeres as end-diastolic
volume exceeds 400 ml.
3. What are three ways by which stroke
volume can be increased?
1QQ #25 for 11:30
Write the number of the one you choose to answer.
1. What is potentially dangerous about
cardiac hypertrophy that accompanies
rigorous physical training?
2. Explain the Frank-Starling Law of the
Heart in terms what happens in cardiac
myofiber sarcomeres as venous return
increases.
3. What are the effects of sympathetic
stimulation on cardiac myofibers?
S 11
Factors that control Cardiac Output by
changing heart rate and stroke volume.
Afterload (MAP)
CO = HR x SV
+ sympathetic
- parasympathetic
VR and EDV
(FSLoH)
Contractility
(catecholamines)
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.
Exercise………increase CO
The report CNN website
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
S 14
Mean Arterial Pressure = Cardiac Output x Total Peripheral Resistance
MAP = CO x TPR
MAP = (HR x SV) x TPR
Who Cares?
Hemorrhage Diagram from memory on Friday November 30th.
Name _________________________________________
On the back side of this page, create a diagram for the following. Your
response must be confined to the reverse side of this page and you must
write legibly. Your response will count 15-20% of the grade on Test 3 and
should require no more than 15 minutes to complete at the beginning of
class on Friday November 30th.
Beginning with a loss of about 1 liter of blood from a vein, diagram the
early events associated with hemorrhage and the negative feedback
responses to hemorrhage in a well-organized diagram. Write legibly!
Completeness, accuracy, and detail, together with the proper
sequence earn maximal points.
The following abbreviations can be used: AI, AII, JGA, mAChR, Hct, Q, SV,
EF, RBC, HR, EDV, ACh, ANH, ADH, CO, TPR, EPO, VR, MAP, EPI, NE,
SAN, aAdR , bAdR, Symp (sympathetic), Parasymp (parasympathetic), PV,
r (radius), Pc, fAP (frequency of action potentials.) Any other abbreviations
must be defined. "If in doubt, write it out!" Use single headed arrows (→)
to indicate sequential relationships and doubled-stemmed arrows to
indicate increases or decreases.
Pressure gradients in systemic vessels
Velocity in systemic vessels
Why is velocity slowest in capillaries and venules?
Flow =ml/min = Riders/min past a location
Velocity = m/sec for each rider
Velocity slows for exchange
Diameter of systemic vessels by type
Cumulative cross sectional area of vessels by type
Why is velocity slowest in capillaries and venules?
S1
Properties of Blood Vessels
All vessels and heart chambers lined with ENDOTHELIAL cells (simple squamous)
• Arteries
• Arterioles Variable Resistance vessels
• Capillaries
Exchange
• Venules
Capacitance vessels, high
• Veins
compliance, low pressure,
Elastic, low compliance, large
diameter, low resistance vessels
Wall = simple squamous endothelium
No smooth muscle; cannot change diameter
valves for unidirectional flow
S4
Fig. 12.30
Stretching elastic connective tissue
Elastic recoil of
stretched arterial walls
during ventricular
systole maintains
arterial pressure during
diastole as blood drains
into arterioles.
Atherosclerosis
Recoil of elastic connective tissue
Point of Confusion: Smooth muscles in arterial walls
DO NOT rhythmically contract, do not pump!
Elastic recoil maintains internal pressure without expending energy
Arteries are a pressure
reservoir to maintain pressure
between during ventricular
diastole and to keep blood
flowing to arterioles during
diastole.
S5
Arteries and Arterial Pressure
Mean Arterial Pressure
Arterioles have two main
functions:
1) regulate flow to tissues
and organs and
2) responsible for Total
Peripheral Resistance
which influences
Mean Arterial Pressure.
MAP = CO x TPR
Poiseulle’s Equation
Arteriole
S6
Fig. 12.50
Heart
Arteries
Mean
Arterial
Pressure
Totol Peripheral Resistance
CNS
Skin
Sk. Muscle
Gut
Arterioles
Kidneys
Cardiac
Output
What regulates the smooth muscle of arterioles?
Extrinsic controls:
Intrinsic controls:
S8
Fig. 12.36
Metabolic vasodilators
No parasympathetic
innervation of arterioles!
Importance of sympathetic
“tone.”
Metabolic autoregulation, flow autoregulation, myogenic autoregulation
Who Cares?
Migraine headaches and sumatriptans
(agonists for 5-HT1 receptors)
to stimulate vasoconstriction.