Download The Cardiovascular System

The
Cardiovascular
System
Ch. 18,19
Introduction

Cardiovascular system

Heart

Blood vessels

Arteries

Capillaries

Veins
Heart anatomy
Structure of the heart

Description-hollow, cone-shaped,
muscular pump

12 cm by 9 cm

Located behind sternum, within
mediastinum (space)
Coverings of the heart

Pericardium – encloses heart – tough connective tissue.


Fibrous pericardium surrounds visceral serous pericardium.

Visceral pericardium- surrounds heart

Parietal pericardium-lines the cavity
Paricardial cavity- space containing serous fluid between parietal and
visceral pericardium – contains serous fluid
Wall of the heart
3
layers
 Epicardium-outermost
layer
 Connective
tissue and
epithelium – contains
blood vessels and
lymph vessels
 Myocardium
– cardiac
muscle, middle layer
 Endocardium –
innermost layer,
contains nervous
tissue for control of
the heart.
Skeleton of the heart

Rings of dense connective tissue

Surround pulmonary trunk and aorta
Heart chambers and valves

Chambers
 Atria
 Ventricles
Septum
 Atrioventricular (AV) valve

 Tricuspid
 Bicuspid
or mitral
Cordae tendinae
 Pulmonary valves
 Aortic valve

Path of blood through heart
Inferior or superior vena
cava

Pulmonary vein

Left atrium

Right atrium

Left AV valve

Right AV valve

Left ventricle

Right ventricle

Aorta

Pulmonary artery

Aortic valve

Pulmonary valve

Body

Lungs

When you come in:
 Prepare
for quiz
 You will be asked to trace
the path of blood through
the heart in written bullet
form, listing the vessels,
structures, chambers,
etc.
4/30/201
7
Quiz
 In
bullet form, list the path of
a blood cell from the foot.
 Include
vessels, structures,
chambers, valves.
There
are 14 – 7pts apiece
Blood supply to the heart
Branches of aorta, carry oxygenated
blood – right and left coronary
arteries – feed heart
 Branches from coronary arteries feed
capillaries of myocardium
 Smaller branches of arteries –
anastomoses – alternate pathways for
blood
 Blocked artery – angina pectoris –
myocardial infarction – heart
attack
 Cardiac veins- drain blood from heart

Heart beating
Heart actions






Cardiac cycle – pressure in
chambers rises/falls with
contraction/relaxation of atria
and ventricles
Atria fill, open av valves
Ventricles fill
Valves close
Ventricles contract, blood
goes through pulmonary artery
and aorta
Ventricles relax, valves close
in vessels
Heart sounds
 Heart
sounds caused by valve
closure
 First
sound (lubb) – ventricles
contract and AV valves close
 Second
sound (dupp) ventricles
relax and aortic and pulmonary
valves close.
Cardiac conduction system





Functional synctium – atrial and
ventricular – mass of fibers that
works as a unit
Cardiac tissue conducts impulses
through myocardium – cardiac
conduction system.
Sinoatrial node in right atrium –
pacemaker – self exciting
Impulses spread through atrial
synctium then ventricular
synctium.
Purkinje fibers contract tiny
muscles attached to chordae
tendinae
Electrocardiogram
 ECG
– electrical recording
of changes that occur in
cardiac cycle
 P wave – depolarization of
atria
 QRS complex –
depolarization of ventricles
 T wave – ventricular
repolarization
Regulation of the cardiac
cycle
Amount of blood pumped must
adjust according to body needs
 SA node innervated by sympathetic
and parasympathetic nervous
system divisions so CNS controls
heart rate.
 Cardiac control center in medulla
oblongata – adjusts heart rate based
on blood pressure measurements
from baro receptors.
 Cerebrum/hypothalamus influence
heart rate as well

Reflection
1.
Why does the heart need its
own blood supply?
2.
What do the heart sounds
signify?
3.
Describe the cardiac
conduction system.
4/30/201
7
Warm up
1.
2.
3.
What would happen to your
cardiac conduction system if
you had a left bundle branch
block?
The natural pacemaker is the
___________________.
What might be malfunctioning
if you constantly have a heart
rate of 100 beats per minute?
4/30/201
7
Blood vessels
 Blood
vessels
include:Arteries
,
arterioles, capillaries,
venules, veins
 Create
closed system –
carries blood away from
heart to cells in body
then back to the heart.
Arteries and veins
Arteries –strong, elastic
 Divide into arterioles
 Wall of artery - smooth muscles
and connective tissue
 Capable of
vasoconstriction/vasodilation –
increases/decreases blood
flow/pressure
 Clogged vessels – artherosclerosis
– diets high in fat

 Diets
high in
fruits/vegetables=add phyto
sterols to blood – scour out plaque
deposits
capillaries
 Smallest
vessels – layer of
endothelium
 Allows
substances to be
exchanged with cells
 More permeability in capillaries
of liver, intestines, glands
 More metabolic activity – higher
number of capillaries
 Precapillary sphincters – regulate
amount of blood entering
capillary bed
 Capillary beds can close down if
more is needed elsewhere.
Exchanges in the capillaries
 Blood
in capillaries – high
oxygen/nutrients
 Diffuse through wall to tissue
 Plasma proteins stay in
capillary
 Hydrostatic pressure – drives
passage of fluids/small
molecules.
 Osmosis causes tissue fluid to
return to blood
 Lymphatic vessels collect
extra fluid and return it to
circulation
Venules and veins
 Venules
– lead from capillaries
– merge to form veins – veins
return blood to heart.
 3 layers with valves to prevent
backflow
 Thinner, less muscular than
arteries
 No high pressure blood
 Function as blood reservoirs
Blood vessels and circulation
Paths of circulation
 Two
divisions
 Pulmonary
circuit – right ventricle
through pulmonary artery to
lungs, then pulmonary veins to
left atrium.
 Systemic circuit – carries blood
from left ventricle through aorta
to body cells and back through
veins into the left atrium
Reflection
Compare
and contrast
arteries, veins and
capillaries
4/30/201
7
Arterial system
Venous system
Blood pressure
 Blood
pressure is the resistance
against the walls of a blood
vessel
 Factors
that affect blood
pressure
 Heart
action
 Blood
volume
 Peripheral
 Blood
resistance
viscosity
Control of blood pressure
adjusting Cardiac output and
Peripheral resistance
 If blood pressure increases, heart rate
slows and blood vessels dilate
 If BP drops, heart rate increases and
blood vessels constrict.
 Vasomotor center of medulla
oblongata controls

Fetal circulation







Two umbilical arteries – carry blood to placenta
Placenta – structure attached to uterine wall – substances
exchanged between blood of mother and baby
Umbilical vein – returns blood from placenta to baby.
Ductus venosus – returns blood from placenta to inferior
vena cava, bypassing liver
Foramen ovale – opening in septum between right and left
atria -allows most of blood to bypass fetal lungs
Ductus arteriosus-small vessel connects pulmonary artery
with aorta, allows more blood to bypass fetal lungs
After birth: Ovale closes, Ductus arteriosus
contracts