Biology 2
THE CARDIOVASCULAR SYSTEM
CARDIOVASCULAR SYSTEM
https://www.youtube.com/watch?v=gVY04NQU
pxk
 How does this video relate to the heart?
 What happens to the man in the video?

SCHEME OF BLOOD CIRCULATION

Pulmonary circulation
 Eliminates
carbon dioxide via the lungs and
oxygenates the blood
 Contains

deoxygenated blood
Systemic circulation
 Delivers
oxygen to all body cells and carries away
wastes
 Contains
oxygen-rich blood
CIRCULATION

Without circulation,
tissues would lack a
supply of oxygen and
nutrients, and wastes
would accumulate

Necrosis = death of body
tissue that occurs when
not enough blood is
flowing to the tissue
HEART SIZE & LOCATION
Average adult heart size is 14 centimeters long
and 9 centimeters wide (fist size)
 Housed within the mediastinum – location
behind the sternum

 Bordered
laterally by the lungs
 The base of the heart lies beneath the 2nd rib
 The apex (distal point of the heart) extends
downward and to the left to the intercostal space
between the 5th & 6th rib
HEART LOCATION
COVERINGS OF THE HEART

Pericardium- encloses the heart and the proximal
ends of the large blood vessels to where it
attaches
Outer fibrous pericardium attaches heart to
surroundings
 Double-layered sac

 Visceral

AKA epicardium
 Parietal

pericardium = innermost layer of sac
pericardium = inner lining of fibrous pericardium
Pericardial cavity- space between the visceral and
parietal layers

Contains fluid that reduces friction as heart contracts
PERICARDIUM
PERICARDITIS
Swelling and irritation of
the pericardium
 Pericarditis often causes
chest pain and
sometimes other
symptoms. The sharp
chest pain associated
with pericarditis occurs
when the irritated layers
of the pericardium rub
against each other.

3 LAYERS OF THE HEART’S WALLS

Epicardium- outer layer
 Also
part of the visceral pericardium
 Made of connective & adipose tissue
 Protects heart by reducing friction

Myocardium- middle layer
 Thick
cardiac muscle tissue
 Pumps blood out of the heart chambers

Endocardium- inner layer
 Epithelial
and connective tissue layer
 Contains elastic fibers, blood vessels, & Purkinje
fibers
3 LAYERS OF HEART WALLS
3 LAYERS OF HEART WALLS
DOUBLE PUMP
The heart is divided into 4 hollow chambers
 Atria- upper chambers have thin walls and
receive blood returning to heart
 Ventricles- lower chambers that receive blood
from the atria and contract to force blood out of
the heart into arteries
 Septum- solid wall that separates the atrium
and ventricle on the right from the atrium and
ventricle on the left

CHAMBERS OF THE HEART
VALVES OF THE HEART

Atrioventricular
valves (A-V valves)ensure one way flow
of blood between
atria and ventricles
 Tricuspid
valvelocated between the
right AV
 Bicuspid valve (AKA
mitral valve)- located
between the left AV
THE VENTRICLES
The right ventricle has thinner muscular walls
as it only pumps blood a short distance to the
lungs
 The left ventricle is thick and must force the
blood to all parts of the body against a greater
resistance to flow

BLOOD FLOW

The right atrium
receives blood from 2
large veins: superior
vena cava and inferior
vena cava
Superior vena cavareturns blood to heart
from upper body
 Inferior vena cavareturns blood to heart
from lower body

BLOOD FLOW
Muscular wall of RV
contracts, blood in
chamber is under
pressure, closing the
tricuspid valve and
forcing the blood out
the pulmonary
trunk, which divides
into the pulmonary
arteries
 Pulmonary arterieslead to lungs

BLOOD FLOW
The LA receives
blood from 4
pulmonary veins (2
from each lung)
 The LV contracts,
closing the bicuspid
valve and pushing
blood through the
aortic valve into the
aorta


Aorta – large artery
that delivers blood to
the body
SEMILUNAR VALVES

The pulmonary and aortic valves are called
semilunar valves due to their half moon shape
of their cusps
MITRAL VALVE PROLAPSE (MVP)
One or both of the cusps of the mitral valve
stretches and bulges into the left atrium during
ventriclar contraction
 Sometimes blood flows back into the left atrium
 Chest pain, palpitations, fatigue, anxiety
 Sounds like a “click and a murmur”
 6% of the population
 More susceptible to endocarditis, which can be
caused by Streptococcus

MITRAL VALVE PROLAPSE
https://www.youtube.com/watch?v=AHBzu5zh
FuA
 https://www.youtube.com/watch?v=KmhKufTS
0wQ

BLOOD SUPPLY TO THE HEART

Right & Left Coronary Arteries- 1st two branches
of the aorta that supply blood to heart tissue
 Feed

the many capillaries of the myocardium
Cardiac veins- drain the blood that has passed
through the myocardial capillaries
(deoxygenated blood)
 These
veins join an enlarged vein on the heart’s
posterior surface called the coronary sinusempties directly into the right atrium