Transcript Circulation of Blood

Anatomy and Function of
the Heart
• Overview: Double Pump
• Goal: Push blood through vessels
• Atria and Ventricles, Heart Valves, Great
Vessels
• Fetal Circulation
• Cardiac Muscle and Heart Attacks
• Control of Heart Rhythm
Larry M. Frolich, Ph.D., Yavapai College
Overview—Double Pump
• Pulmonary Circuit:
Right side of heart
pumps blood to lungs
to pick up oxygen
• Systemic Circuit: Left
side of heart pumps
blood to rest of body to
deliver oxygen
• Schematic does not
show left/right
symmetry for most of
circulatory system
Goal—push blood through vessels to capillaries
• Pulmonary circuit—right side of
heart pumps blood through
pulmonary arteries to capillaries
• Oxygen diffuses into blood and
RBC’s in lungs at alveoli
surrounded by capillaries
• Pulmonary veins return blood to
left side of heart
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Systemic left side of heart
pumps blood through
systemic arteries to
capillaries
Oxygen diffuses out of
blood and into interstitial
fluid around cells making
oxygen available for
cellular metabolism. This
is the grand goal of the
circulatory system—where
the real action happens
Besides oxygen, water,
glucose and other nutrients
are delivered; CO2, waste
products are picked up
Systemic veins return
blood to right side of heart
Heart Board Drawing
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Apex
Ventral view—ventricles
Interventricular sulcus—between right and left ventricles
Right ventricle leads right into pulmonary trunk (to lungs)
Left ventricle leads into aorta (to systemic circulation)
emerging behind pulmonary trunk
• Auricle of right atrium
• Pulmonary veins entering right atrium on posterior
surface
• IVC, SVC enter left atrium on posterior surface
Another View
Right Atrium
• Receives low O2 veinous
blood from body (return of
systemic circulation
– Superiorly SVC (superior
vena cava
– Inferiorly IVC (inferior vena
cava)
– Thin muscular wall
• At atrial systole, the right
atrium contracts pushing
blood into right ventricle
passing through open
right A-V valve (tricuspid
valve)
• Fossa ovalis is remnant of
foramen ovale that shunts
fetal blood into left atrium
Right Ventricle
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Receives blood passing through
open A-V valve from right atrium
At ventricular systole, the right
ventricle contracts pushing blood
into the pulmonary trunk passing
through the open right semilunar valve (pulmonary valve)
As the ventricle begins to
contract, the blood pushes
against the cusps of the A-V
valve causing it to snap shut
preventing blood from backflowing into the right atrium
(“lub…”)
The papillary muscles then
contract and pull on the chordae
tendinae attached to the valve
cusps so they don’t get overextended into the atrium
As ventricle relaxes into diastole,
the right semilunar valve
(pulmonary valve) snaps shut
keeping blood from back-flowing
back into the ventricle (“…dub”)
Left Atrium
• Receives high O2 veinous
blood from lungs (return of
systemic circulation
– Pulmonary veins—2 from
left lung, 2 from right lung
• At atrial systole, the left
atrium contracts pushing
blood into left ventricle
passing through open left
A-V valve (bicuspid or
mitral valve)
Left Ventricle
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Receives blood passing through
open A-V valve from left atrium
At ventricular systole, the left
ventricle contracts pushing blood
into the aorta passing through the
open left semi-lunar valve (aortic
valve)
As the ventricle begins to
contract, the blood pushes
against the cusps of the A-V
valve causing it to snap shut
preventing blood from backflowing into the left atrium
(“lub…”)
The papillary muscles then
contract and pull on the chordae
tendinae attached to the valve
cusps so they don’t get overextended into the atrium
As ventricle relaxes into diastole,
the left semilunar valve (aortic
valve) snaps shut keeping blood
from back-flowing back into the
ventricle (“…dub”)
Animation of heart and blood flow
• Fetal Circulation
• No circulation to lungs—why?
– Foramen ovale shunts blood from
right atrium to left atrium
– Ductus arteriosum shunts blood
from pulmonary artery to aortic arch
• Circulation must go to placenta
– Umbilical aa., vv.
Fetal Circulation
Adult remnants of fetal circulation
Adult
Fetus
Fossa ovale
Foramen ovale
Ligamentum arteriosum
Ductus arteriosus
Medial umbilical ligaments
Umbilical aa.(within fetus)
Round ligament
(ligamentum teres) of liver
Ligamentum venosum
Umbilical v.(within fetus)
Medial umbilical ligament
Umbilical cord (leaving fetus)
Ductus venosus
Coronary arteries and circulation to the heart
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Coronary arteries supply
blood to heart muscle
Come directly off of aorta
as it leaves the heart
from large high pressure
aorta to small left and
right coronary arteries
Heart attack is loss of
blood supply to heart
muscle
Blockage usually occurs
in first two centimeters of
coronary arteries
Treatment can be
angioplasty, stint, bypass
Cardiac Muscle
A and P I Tissue Review—3 types of muscle tissue
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Usually 1 nucleus, sometimes several
Much thinner than skeletal muscle (20 um versus 100 um)
Intercalated disks pass action potential from cell to cell—most cells have no direct
motor neuron connection
Energy source is mostly lipids
Calcium to trigger actin-myosin cross-bridge formation and muscle cell contraction
comes from outside cell as part of action potential as well as from sarcoplasmic
reticulum
Control of heart rhythm
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Heart receives
visceral motor
innervation
– Sympathetic
(speeds up)
– Parasympathetic
(slows down)
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Input is from
chemoreceptors
and baroreceptors
Input on blood pressure to brain
• Chemoreceptors
– aortic bodies, carotid bodies
– Sense CO2, pH, O2
• Barroreceptors
– stretch receptors sense blood
pressure pushing on vessel wall
– aortic sinus, carotid sinus
Bonus A and P I Review:
Cranial Nerve that carries aortic
receptor input to brain? X. Vagus
Cranial Nerve that carries carotid
receptor input to brain?
IX. Glossopharyngeal
Reflexive output: heart rate
• Baro- and chemo-receptor
input arrives to medulla
oblongata (A and P I review!)
• Autonomic motor output (A and
P I review) to AV node of heart
– Sympathetic will speed heart
rate (where do sympathetic
neurons originate? What is
path to heart?
– Parasympathetic will slow
heart (where do
parasympathetic neurons
originate? What is path to
heart?)
• Bonus (common sense
physiology!): Will blood
vessels constrict or dilate with
sympathetic response?
A and P I Review
Sympathetic = “fight or flight” =
NE (norepinephrine)
Parasympathetic = calming =
ACH (acetylcholine)
Electrocardiogram
• Surface electrodes
measure sum total
of action potentials
in cardiac muscle
• Distinct wave forms
for atrial, ventricular
depolarization
• Intervals as well as
wave forms
important in
interpretation
Demo in Lab
Location of Heart in Thorax
Heart Dissection Lab