Lab 4: Heart sounds and vessels
Overview
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•
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•
Review
Heart sounds
Blood supply to the heart
Blood vessels
– Veins
• Portal systems
• New lab website:
http://isu.indstate.edu/~jowhitak/cmritzi.htm
• Practical lab review: Sunday 2-5 pm
Review
• How do volume and pressure in the ventricles
change during atrial contraction?
• What region of the heart controls the electrical
signal through the heart?
• Which standard limb lead has a negative lead on
the right arm and a positive lead on the left arm?
Overview
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•
•
•
Review
Heart sounds
Blood supply to the heart
Blood vessels
– Veins
• Portal systems
Heart sounds
“lubb-dubb”
• S1: longer and louder
• S2: softer and shorter
• S3: found in children and juveniles
• S1 & S2 occur in conjunction with the
opening and closing of valves
• Actually caused by turbulence of blood
Valvular troubles
• Valvular Insufficiency:
valve failure causing
backwards flow
• Any defect in the
valves can lead to heart
failure
• Defective valves can be
replaced with artificial
valves or with pig
valves
Valvular Troubles (cont)
• Mitral valve prolapse: tri- or bicuspid cusps bulge
back into the atrium.
– Symptoms: chest pain, fatique, shortness of breath
– Cause: hereditary
• Valvular Stenosis: cusps of the valve are stiff and
opening is constricted by scar tissue
– Results from autoimmune disease
– Causes enlarged heart
– Blood moving backwards through the valves causes a
heart murmur
Break for Dynamic Human
Blood supply to the heart
muscles
• The endocardium prevents blood from
seeping through the heart
• How is blood supplied to the myocardium
and the pericardium?
– Coronary arteries originating from the aortic
arch
Arteries in the heart
Aorta
Right Coronary
Marginal artery
Left Coronary
Circumflex Artery
Posterior IV Artery
Anterior IV Artery
Anastomoses
Anastomoses
• Point where two
arteries join to reach a
common destination
• If one artery becomes
blocked, the other can
take blood to the
appropriate destination
Arteries of the heart
Veins in the heart
Greater Cardiac Vein
Small Cardiac Vein
Middle Cardiac Vein
Coronary Sinus
Right Atrium
Coronary Veins
Artherosclerosis
• Contributes to over
710,000 heart attack
and stroke, and
peripheral
vascular disease deaths
each year.
• Fatty blockage in
coronary
artery
Artherosclerosis
• Cause: Abundance of low-density lipids
and defective receptors for LDL in the
coronary arteries.
– LDL: cholesterol, free fatty acids and
phospholipids
– Arterial cells with defective receptors will take
in too much cholesterol
– Results in obstruction of the arterial lumen
Cardiac Ischemia and Infarction
• Ischemia: Loss of blood flow
• Infarction: Death of myocardial cells; heart attack
• Cause: Artheriosclerosis blocks a cardiac artery.
The downstream region does not receive enough
oxygen causing cell death. The death of these
cells weakens the heart wall disrupting electrical
pathways leading to fibrillation.
Break for Dynamic Human
Overview
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•
•
•
Review
Heart sounds
Blood supply to the heart
Blood vessels
– Veins
• Portal systems
Blood Vessels
Arteries
Capillaries
Veins
Structure of Blood Vessels
• Tunica externa: loose
connective tissue
• Tunica media: smooth
muscle, elastin,
collagen
• Tunica interna:
endothelium
Types of Arteries
• Conducting (elastic)
– Passively accommodate blood flow
• Distributing (muscular)
– High smooth muscle content
– Deliver blood to specific organs
• Arterioles
– Control blood flow
– Link to capillaries
Capillaries
• Pre-capillary
sphincters
– Open and close
capillary beds
– ¾ of all capillaries are
ususally closed
• Structure:
endothelium only
Types of Capillaries
• Continuous: uninterrupted
tube
– Only allow small solutes
such as glucose to enter
– Blood-brain barrier
• Fenestrated: riddled with
pores
– Allow rapid passage of
small molecules
– Hold proteins in the vessels
– Important in organs that
engage in rapid filtration
Veins
• Venules: Collect blood from capillaries
– Porous
• Veins:
– Lower pressure than the arteries
– Thinner walls (little tunica media or externa)
but larger lumens
– Walls expand easy and accomadate more blood
than arteries
How does blood travel in veins?
1. Messaging action of skeletal muscle
2. Pressure gradient in the body:
– Positive pressure in the abdominal cavity and
negative in the thoracic cavity draws blood up
Venous Valves
3.Venous valves prevent
backflow
• Failure of valves
results in varicose
veins
Special Circulations: Portal
Systems
• Portal systems:
Blood flows between
two consecutive
capillary beds before
returning to the heart
Artery
Capillary 1
Capillary 2
Vein
Hepatic Portal System
• Connects capillaries of
the intestines to
capillaries of the liver
• Delivers newly
absorbed nutrients to
the liver
Hypothalamo-hypophyseal portal
system
• Connects
hypothalamus to
pituitary gland
• Responsible for
transporting hormones
Dynamic Human
Overview
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•
•
•
Review
Heart sounds
Blood supply to the heart
Blood vessels
– Valves
• Portal systems
• Cat heart and human heart
Cat Dissection
• Finish identifying arteries and veins
• Remove cat heart and dissect in half
– Valves and chambers
– Chordae Tendinai
– Coronary Arteries