The first time ever I held you near
and felt your heart beat close to mine
I thought our joy would fill the world
and would last till the end of time, my Love.
--Peter, Paul and Mary

Circulation

Assignment

Audesirk, Audesirk & Byers Chapter 32, Case study, Chapter 12

Today's musical selection
Huey Lewis and the News Heart of rock and roll

Pep talk

Figure (chapter 12 opener)
Flo Hyman, 1984 Olympic silver medalist, died at age 32 when her aorta ruptured.
She had a dominant mutation of fibrillin

Figure (chapter 13 opener)
St. Louis Cardinals pitcher Darryl Kile died at age 33 in 2002.
He had blocked coronary arteries, and there was a family history

Overview

In multicellular metazoan, need a vascular system (in terestrial plants above mosses, xylem and phloem)
Circulation : Cardiovascular system

Figure 32-1
Open circulation Blood = interstitial fluid - hemolymph is term for blood - most molluscs and all arthropods have open circulation
hemocoel is the space where the blood is
- important in insects that gas transport (via air filled trachea) does not rely on circulation being closed
Closed circulation - annelids, cephalopods, echinoderms, vertebrates

Figure 32-2
Chambers of heart -
Fish have 2 chambers (gills and body "wired" in series)
The "circuit" is "in series" - heart -> gills -> body -> back to heart
Amphibia and reptiles have 3 chambers (2 atria, 1 ventricle)
As long as blood does not fully mix, there is some separation of non-oxygenated blood to the pulmonary circulation and of oxygenated blood to the systemic circulation

Anatomy of the heart

Figure 32-3
Note that right is drawn on left as if looking into the chest of a supine subject

Figure 32-2
Here is the circuit: LA - LV - Arteries (aorta, etc.) (blood pressure taken here) - Arterioles (regulate blood flow to muscles, brain, digestion, kidneys and skin) - Capillaries (near, exchange, WBC's) - venules - veins (no pressure, valves)- RA - RV - Pulmonary arteries - Lung capillaries - Pulmonary veins -

Heart valves and sounds

Figure 32-3
pulmonary valve (semilunar) feeds pulmonary arteries
aortic valve (semilunar) feeds aorta
These valves snap shut from arterial back pressure at the end of systole to make second heart sound- "dub"
Superior and inferior vena cava feed right atrium -> ventricle via tricuspid (atrio-ventricular) valve.
Pulmonary veins feed left atrium -> ventricle via bicuspid (atrioventricular) valve.
Tricuspid & bicuspid snap shut at start of ventricular contraction to make first heart sound- "lub."
If there is backslosh through valves, this is called a heart murmur.

Blood vessels

Figure 32-14
artery is like hose
blood flow to emptying into vascular bed: regulation by smooth muscle of arteriole
capillary is one layer of endothelial cells

Figure 32-16
Blood moves slowly and with very little pressure in veins. Movement in veins is mostly passive with a series of valves and where contraction of skeletal muscles helps

Figure 32-17
Lymphatic circulation helps to percolate interstitial fluid back to circulation

Cardiac cycle and blood pressure

Figure 32-5
cardiac cycle
Diastole (between heart beats), systole is during ventricular contraction, hence terms systolic and diastolic blood pressure.
Ventricle fills during diastole.
Ventricle empties during systole.
Ventricular pressure builds during systole.

Measuring blood pressure

It is arterial blood pressure that is usually measured.

Figure 32-6
close off artery, when it opens (systolic pressure), blood flow is turbulent and noisy (Korotkoff sounds), when it is always open (diastolic pressure), blood flow is no longer noisy
Blood pressure is measured in arteries
High blood pressure is called the "silent killer."
hypertension 45 million Americans - salt intake is still debated, >140/95 high 140/70 normal
high diastolic is especially bad

Myocardial cells

Figure 32-4
Heart muscle cells branch and come together and are joiined at intercalated discs with gap junctions that spread the electrical signal from cell to cell.
cardiac muscle - automatic (explained below)
here is a picture from our histology course of heart muscle cells joined at intercalated discs

Electrical activity of heart cells

Figure 32-7
Electrical - SA (sinoatrial) node (or electrical pacemaker) - spread - automatic.
Sympathetic nervous system speeds it up, parasympathetic nervous system slows it down.
AV (atrioventricular node) is eventually stimulated.
If it were not, it is also automatic but slower and would generate a heart beat in the venticals.
Bundle of His, bundle branches, and Purkinje fibers get ventricular depolarization to happen almost synchronously.

The ECG

electrocardiogram
This will be covered in lab
Because a lot of cells in heart work together, and because extracellular fluid has high conductivity, electrical activity can be recorded non-invasively.
P is atrial depolarization.
QRS is ventricular depolarization.
T is ventricular repolarization.

Atherosclerosis


Figure W32-1
A layer of fat with ccholesterol between media and externa
ulceration lining lumen
atherosclerosis - hardening of the arteries - plaques
atheroma with macrophages
Cholesterol is a problem

Heart attack

General:
Myocardial cells not regenerate (by mitosis in the adult). This is why heart attack is so damaging. The same is true for the nerves in the central nervous system where similar damage is called stroke.
Coronary arteries clog -> myocardial infarction - coronary thrombosis - ischemia (too little blood flow for oxygen delivery)
Angina, chest pain, and referred pain
Heart muscle is aerobic
Anaerobic metabolism would build up lactic acid and cause pain (angina pectoris)
In CPR (cardiopulmonary resuscitation) chest pressure keeps blood flowing a little and rescue

Platelet aggregation - thrombus (local), embolism (from elsewhere) cause ischemia
tissue plasmogen activator (TPA) dissolve clots
aspirin inhibits clotting, coumaden is a strong anticoagulant

Figure E32-2
catheter with balloon angioplasty insert stent

Figure E32-3
bypass operations, replace coronary artery with vessel from somewhere else in the body,

Risk facrors for heart attack
(1) High blood pressure (the silent killer) -- Wiggers diagram --heart has to work harder to open semilunar valves.
(2) prior heart attack
(3) smoking
(4) diabetes
(5) family history -

Prevention -
(1) exercise - increase HDL (endothelial cells do not take up)
(2) antioxidants (oxidized LDLs in endothelial cells are bad)
(3) alcohol in moderation (but people who die of cirrhosis rarely have atherosclerosis)
(4) statins

Questions used in 2007 & 2008 related to this outline

A thrombus is
A) a blood vessel that feeds the heart.
B) the smooth muscle that controls blood flow to a capillary bed from an arteriole.
C) a phagocytic cell full of cholesterol.
*D) a blood clot that clogs an atherosclerotic artery.
E) the muscle cells that regrow after a heart attack.

An open circulatory system
A) is present in amphibia and reptiles.
B) feeds the lungs in humans.
*C) percolates hemolymph into and out of the hemocoel in insects.
D) refers to the valves between the ventricles and the arteries.
E) is exemplified by the cardiovascular system in birds and mammals.

Which is one reason heart signals can be recorded by connections to the wrists and ankle?
A) because of ischemia.
*B) because there is little electrical resistance in extracellular fluid.
C) because of angina.
D) because of Korotkoff sounds.
E) because of the endothelium.

The "silent killer" is
A) plaque.
B) HDL.
C) heart murmers.
D) diabetes.
*E) high blood pressure.

What keeps blood moving forward through veins in the body's systemic circulation?
A) the driving force of blood pressure.
*B) valves.
C) the AV node.
D) the pulmonary circulation.
E) systole.

The right ventricle sends blood to the
A) aorta.
B) left atrium.
C) vena cava.
*D) pulmonary circulation.
E) lymph vessels.

Balloon angioplasty
A) is used to record the electrocardiogram.
B) measures the diastolic blood pressure.
*C) is used to open atherosclerotic coronary arteries.
D) conducts the electrical signal across intercalated discs.
E) triggers the heartbeat.

Insects have
*(a) an open circulatory system and separate gas transport via air-filled trachea.
(b) a circulatory system that is more like that of vertebrates than of arthropods.
(c) xylem and phloem.
(d) 5 hearts and a closed circulatory system.
(e) a three-chambered heart where one ventricle might allow mixing of systemic and pulmonary blood.

Why is the wall of the right ventricle thinner than that of the left ventricle?
(a) The right ventricle creates systolic blood pressure while the left ventricle determines diastolic blood pressure.
*(b) There is not as much pressure in pulmonary circulation as there is in the systemic circulation.
(c) The right ventricle creates hypertension while the left ventricle is for lower pressure.
(d) The right ventricle makes Korotkoff sounds while the left ventricle makes lub-dub sounds.
(e) The right ventricle pumps to the aorta while the left ventricle pumps to the left atrium.

Atrioventricular valves are open
(a) never.
(b) when muscles contract against the veins.
(c) when stress regulates blood flow to different beds of capillaries.
*(d) during diastole.
(e) while the ventricles are pushing blood into the arteries.

Blood pressure measurements involve
(a) listening to the "lub-dub" heart sounds.
*(b) listening for turbulent blood flow in an artery.
(c) measurements from veins.
(d) electrical measurements from heart muscle.
(e) coronary bypass

Intercalated discs hold heart muscle cells together. What other function do they serve?
(a) They help in the conversion of CO2 plus H2O to H2CO3.
(b) They allow HDL buildup in atherosclerotic plaques.
*(c) They allow electrical connection by gap junctions.
(d) They keep blood from flowing backwards during ventricular contraction.
(e) They hold open a partially closed coronary artery.

Electrical activity in the heart usually starts in the
*(a) SA node.
(b) pulmonary arteries.
(c) thrombus.
(d) medulla of the brain.
(e) angina pectoris.

The term for too little blood flow for adequate oxygen delivery is
(a) laryngitis.
(b) cirrhosis.
(c) hypertension.
(d) peristalsis.
*(e) ischemia.

Amphibia and reptiles
A) have a two-chambered heart.
*B) have a three-chambered heart.
C) have an open circulatory system like an insect.
D) have multiple hearts like an earthworm.
E) do not have a vascular system.

How is the amount of blood flow to the different capillary beds of the body regulated?
A) by valves
B) by the cerebral cortex
C) by the size of the veins
*D) by smooth muscle of arterioles
E) by insulin

Diastolic and systolic blood pressures
A) are from systemic and pulmonary circulations respectively.
B) are from atria and ventricles respectively.
C) should be the same as eachother in healthy people.
D) are measured from veins.
*E) are measured from arteries.

Questions used in 2003 relating to this outline

Blood goes from the right ventricle to the
(a) pulmonary vein.
*(b) pulmonary artery.
(c) aorta.
(d) vena cava.
(e) right atrium.

CPR
(a) reduces HDL.
(b) reduces LDL.
(c) restores the heart beat.
*(d) circulates oxygenated blood to the brain.
(e) prevents atherosclerosis.

During atrial and ventricular diastole
*(a) AV valves (tricuspid and bicuspid valves) are open.
(b) semilunar valves are open.
(c) the QRS complex of the ECG is generated.
(d) ventricles contract.
(e) blood pressure measured with a cuff on the arm is highest.

The SA node
(a) can have its lumen clogged by a thrombus in a heart attack.
*(b) initiates the electrical activity in the heart beat.
(c) requires a nerve connection, and the heart would stop in severe polio.
(d) is the part of the brain that stimulates breathing when O2 is low.
(e) connects the hypothalamus to the anterior pituitary.

How does electrical excitation spread throughout the heart?
(a) via plasmodesmata
(b) by neurotransmitters
(c) by interleukins
*(d) by gap junctions
(e) by neurons

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