Transcript Cardiovascular System - Belle Vernon Area School District

Cardiovascular System
I. Functions of the heart.
1. Generating blood pressure.
2. Routing blood.
3. Ensuring blood moves one way.
4. Regulating blood supply.
Cardiovascular System
II. Heart
A. General Characteristics
 1. 100,000 time/day
 2. 4,00L/day = 1,000
gallons
 3. 60,000 miles of blood
vessels
 4. Center of the
circulatory System
 5. Center of the Thoracic
Cavity, between the
lungs
 6. 2/3 on the left side
 7. Decreases in size
after the age of 65.
B. Coverings of the heart
1. Pericardium - covers the heart, 2 main layers
a. Parietal Cardium (pericardial sac)
•Outer
•Loose fitting
1. Fibrous - Outer, thick, tough
dense connective tissue.
Protects & anchors to the
diaphragm
2. Serous - Inner, thin, Squamous
epithelium
b. Visceral Pericardium (Epicardium)
•Attaches to the surface of the
heart
•Considered to be the outer most
layer of the heart.
c. Pericardial Cavity
•Space filled with fluid
•Lubrication
•Percarditis - swelling of space
C. Heart Walls
3 layers - middle is the most important
- Myocardium
1. Epicardium - Thin protective
barrier of the heart
Serous membrane
Fat deposits
2. Myocardium -Bulk of the heart
Fibrous skeleton - bundles of
connective tissue
Layer that contracts
3. Endocardium- Inner most layer
Smooth white layer
 Squamous epithelium
D. Heart Chambers
Superior
1. Atria - Receiving chambers
for blood
Min. role in pumping
Pectinate Muscles - ridges of
muscle
Interatrial Septum separates the atrium into
right & left halves
Fossal Ovalis - oval
depression of the heart
believed to be an opening in
the fetal heart
a. Right Atrium - receives
from the vena cava
b. Left Atrium receives from
the lungs
Inferior
2. Ventricles - forces blood through
the body
Trabeculae Carnae - Irregular
folds of muscle in the
endocardium
Papillary muscles - Slender
projections off of the trabuclae
carnae
 Attaches to valves & aids in
function
Interventricular Septum Separates ventricles into left &
right halves
Coronary Sulcus - Externally
separates the atrium & ventricles
E. Heart valves
Blood flows in one direction
Prevents back flow

1. Atrioventricular valves (AV) between atrium & ventricles
2 or 3 triangular flaps or cusps
Point downward into the
ventricles
Tricuspid between right Atrium &
ventricle (3 flaps)
Bicuspid (mitral) between left atrium &
ventricle (2 flaps)
Chordae tendinae - strands of
connective tissue
Anchors cusps to papillary walls of the
ventricles
Murmur - Cusps do not lose completely
- leaking of blood
2. Semilunar (SL) Valves
Between ventricles & blood leaving
Pulmonary & Aortic
3 half moon (semilunar) cusps
F. Blood flow through the heart
G. Supply of blood to the heart
Coronary Circulation
Right & Left Coronary Arteries - carries fresh oxygenated blood
(70% of oxygen, only 25% to skeletal muscles, increases to 70%
during exercise)
Great & Small cardiac vein
Coronary Sinus - large vein that collects blood leaving the heart
II. Heart Physiology - Pumps blood through out the
body
A. Cardiac Cycle - contraction of both the atria &
then ventricle.
1. Systole - Contraction
2. Diastole - Relaxation
B. Heart Sounds - LUB - DUB Closing of the heart
valves
1. Lub - Closing of the AV valves
2. Dub - Closing of the Sl valves
C. Heart Conduction - Each
cardiac cycle is stimulated
by special conducting cells
in the heart.
1. Receives a signal form
the autonomic nervous
system.
2. Sinoatrial (SA) Node
“Pacemaker” - cluster of
pace setting cells
Initiates each cardiac cycle
by generating an electric
impulse.
Spread quickly through out
the atrium.
Stimulates the second
cluster of cells.
3. Atrioventricular (AV) Node,
AV. bundle, Bundle of His relays the signal to the
ventricles.
Extends down the septum of
the heart.
4. Purkinje fibers - branches of
the AV node, passes further
into the myocardium.
5. If the SA node is unable to
produce the electrical impulse
for the heart to contract, the
AV node functions as the
pacemaker
6. Slower – Ectopic beat.
D. Electrocardiogram (ECG or EKG) measures the electrical events
during a cardiac cycle
1. Detect changes in the
electrical changes in the
heart wall
2. Electrical changes produces a
changes in the ionic flow
through out the body
SA node fires send action potential.
P Wave - depolarization of the atria action potential.
QRS Wave - depolarization of the
ventricle.
T Wave ventricular repolarization of
the ventricle
PQ interval – atria contract
& begins to relax.
QT interval – ventricle
depolarizes &
repolarizes.
E. Cardiac Output - Volume of blood pumped
1. Heart rate X Stroke Volume = Cardiac Output
75 bpm X 70 ml
= 5250 ml/min (5.25
L/min)
2. Adjustments - exercise
Heart rate
Stroke Volume
3. Starling’s Law - Further the heart is stretched,
the stronger the contraction.
Preload – pressure on the heart when the
ventricles are stretched when filling with
blood.
Afterload – pressure the heart must beat
against.
F. Regulation of Heart Activity
1. Controlled by the reflex center (cardioregulatory
center) - medulla oblongata.
2. Baroreceptors - detect the blood pressure.
3. Parasympathetic fibers from the medulla
oblongata through the Vagus nerve extends to the
heart.
Acetylcholine (Ach) slows the heart
Norepinephrine (NE) speed the heart up
Barorecptor relfex
G. Cardiac cycle
Three major events in the cycle.
1. Systole –
a. Blood is pushed towards the
atria, closely the AV valves.
b. Pressure increases in the
ventricle forcing the SL valves to
open.
2. Diastole –
a. Pressure in the ventricles
decrease, the AV valves open and
blood fills the ventricles up to 70%
of their volume.
3. EndAtria relaxes & fills with blood, then
contract & starts it over.
Cardiac Cycle
III. Aging
A. By 70 output is reduced by 30%, by 85 30%60%.
B. Hypertrophy is common (enlargement of left
ventricle), due to increase afterload (high blood
pressure).
Leads to decreased elasticity & increased
stiffness.
Increased left atria pressure and cause
pulmonary edema, feel out of breath.
C. Greater amount of time to contract & relax
leading to decreased in maxmium heart rate.
D. Connective tissue with the valves becomes less
flexible.
E. Development of coronary artery disease in 10%
of people over 80.
VI. Cardiovascular diseases
A. Congestive heart failure - failure of the heart to pump
blood to the body tissues.
B. Heart Block – Failure of the SA or AV. to generate
impulses.
C. Heart fibrillation - Heart beats at a irregular pace.
D. Heart flutter - heart race up to 300 bpm.
E. Hypertension - elevated blood pressure.
F. Murmur - Leaking of blood through a closed valve.
G. Myocarditis - infection of the heart muscle.
H. Pericarditis - Infection of the pericardial sac
which results in thicken or scarring.
1. What are the three types of blood vessels
and how are they different?
2. What is the difference between
vasodialation & vasoconstriction?
3. What are the 3 layers of the blood vessels?
4. Does blood ever flow in reverse within the
blood vessels?