Unit 4 - Cardiovascular System

What do Cells Need to do to Survive

cells must exchange materials with their environment

Diffusion Moves

oxygen and nutrients → into cells

carbon dioxide and waste → out of cells

Why Cardiovascular System is Needed

provides fast transport between body cells and external environment

3 Components of Cardiovascular System

the heart, blood vessels, blood

The Heart

muscular pump that moves blood through blood vessels

Blood Vessels

series of tubes that carry blood throughout body

Blood

fluid medium, accounting for 7-8% of body weight

transport substances to and from cells

Main Function of the CV System in Transport of Substances

• oxygen and nutrietns to cells/tissues

• wastes and CO2 to liver and kidneys

• hormones, immune cells, and clotting proteins to specific target cells

Functions of the Heart

perform sensrory and endocrine functions

helps regulate BP and blood volume

Functions of the Blood Vessels

regulate BP

regulate distribution of blood to organs

Functions of Blood

transports hormones

work with the nervous system for communication

The Heart is AKA

the central pump

Upper Chambers in the Heart

receiving chambers

atria → receive blood retruning to the heart

Lower Chambers of the Heart

pumping chambers

ventricles → pump blood away from the heart

Left Side of the Heart

left atrium and ventricle

Right Side of the Heart

right atrium and ventricle

Septum

wall seperating left and right sides of heart

prevents blood from mixing

Interatrial Septum

separates atria

Interventricular Septum

sperates ventricles

Blood Vessels AKA

the vasculature

The Vasculature Carries Blood

from the heart → through the body → back to the heart

What Kind of System is the CV System

a clsoed system because blood remains insdie vessels

Path of Blood Through the CV system

ONE WAY PATH

Arteries (and blood)

carry blood away from the heart (large vessels)

Arterioles (and blood)

deliver blood to capillaries

Capillaries (and blood)

are a site of exchange between blood and tissues

Veules

small vessels leaving capillaries

Veins (and blood)

carry blood back to the heart

Bloods Volume

half of its volume is cells

Red Blood Cells (Erythrocytes)

contain hemoglobin which carries oxygen

White Blood Cells (Leukocytes)

defend the body agaisnt infection

Platelets

improtant for blood clotting

Plasma

liquid portion of blood (made of mostly water, but contain proteins and electrolytes)

Pulmonary (lung) Circuit

exchange gases in the lungs

carries deoyxgenated blood from the heart to lungs → blood becomes oxygentated in lung capillaries → returns oxygenated blood to heart

What Supplies the Pulmonary Circuit

the right heart

• leaves right heart (right ventricle) to lungs via pulmonary arteries, and returning from ling to left heart (left atrium) via pulmonary veins

Systemic Circuit

deilver oxygen and nutrients to body tissues

carries oxygenated blood from heart to body tissues → oxygen is used by cells → blood becomes deoxygenated → returns to heart

Systemic Circuit Transports Blood

systemically (all tissues - except the lungs)

What Supplies the Systemic Circuit

the left heart

• to sytemic tisssues via arteries, arterioles, capillaries and returning from tissues via venues, veins, vena cava → to right heart

Oxygenated Blood

high O2 → bright red color

Deoxygenated Blood

low O2 → dark red color

Path of Blood Flow

1. oxygenated blood leaves heart through the left ventricle → aortic valve → aorta 

2. aorta → systemic capillaries where blood becomes deoxygenated

3. systemic veins → venae cavae → right atrium 

SVC → blood from upper body; IVC→ blood from lower body 

4. blood passes through right atrium → tricuspid valve → right ventricle

5. right ventricle → pulmonary semiulnar valve → pulmonary trunks → pulmonary arteries which carry deoxygenated blood 

6. blood becomes oxygenated in the lungs → pulmonary veins carry it to left atrium 

7. blood passes from left atrium → bicuspid valve → left ventricle (then cycle repeats)

Where is the Heart Located

in the thoracic cavity

The Diaphragm

seperates abdominal cavity from thoracic cavity

Heart Size

size of a fist

Weight of Heart

weighs 250-350 grams (depending on male or female)

Pericardium

membranous sac surround the heart

lubricates the heart and decreases friction

Layers of the Heart

epricardium (outer layer)

myocardium (middle layer)

endocardium (innter layer)

Epicardium

visceral pericardium (layer of connecvtive tissue)

cover the heart (protects heart)

Myocardium

muscular layer of heart

concentric layers of cardiac muscle tissue

atrial myocardium wrpas around great vessels

Endocardium

epithelial cells

provides protection for valves and heart chambers

Myocardium Job

produces the pumping action of the heart

• contract and relazes rhythmically

Myocardium During Contraction

heart wall moves inward

chamber pressure increases → blood is pushed out

Myocardium During Relxation

chambers expands → blood fills chamber

Atria

only push blood to ventricles

Ventricles

pump blood to lungs or whole body

• ventricles have thicker muscles than atria

Right Ventricle

thinner, pumps blood only to lungs

Left Ventricle

thickest, pumps blood to entire body

Cardiac Cycle

changes pressure inside chamber which causes blood to flow

How Does Blood Flow

travels from area of high pressure to low pressure

Pressure Within Chambers of the Heart

varries with heartbeat cycle

Blood Flow Through the Heart

artria to venticles → ventricles to arteries

What do Valves do for Blood

ensure one way blood flow → prevents backflow of blood

When do Valves Open

passively based on pressure gradient

Fiborus Skeleton of the Heart

layer of fiborus connective tissues separating atrial and ventricular muscle

Functions of Fiborus Skeleton of the Heart

anchors heart valves

provides structural support

Atrioventricular (AV) Valves Location

between atria and ventricles

AV Valves Allow

blood flow from atria —> ventricles

AV Valves Prevent

blood from flowing back into atria

When do AV Valves Open or Close

in response to cyclic changes in pressure

• open when atrial pressure > ventricle pressure

Valves on Right Side of the Heart

right AV valve = tricuspid valves (has 3 cusps)

Valves on Left Side of the Heart

left AV valve = bicuspid valve = mitral valve (has 2 cusps)

How Are Valves Connected to Myocardium

by chordae teninae & papilary muscles

• prevents AV valves from everting

Semilunar Valve Location

between venticles and arteries

Semilunar Valves

aortic and pulmonary valves

Aortic Valve

between left ventricle and aorta

Pulmonary Valve

between right venticle and pulmonary trunk

Function of Semilunar Valve

allow blood flow from ventricles to arteries

prevent back flow into ventricles

How Semilunar Valves Work

open when → ventricular pressure > arterial pressure

close when → arterial pressure > ventricular pressure

Valve Prolapse

when valve cusps are pushed backward into the atrium

Results of Valve Prolapse

valve does not close properly → blood may leak backward

Cardiac Muscle Contractions

are myogenic → they originate within heart muscle itself

Autorhythmicity

ability of the heart to generate its own rhythmic eletrical signals

Contractile Cells (Myocardium)

account for 9% of cardiocytes

generate the “pumping” action of the myocardium

Autorhythmic Cells (Conduction System)

can generate/spread actions potentials spontaneously

Pacemaker Cells

spontaneously generate AP’s

determine rate or pace of heart beat

Conduction Fibers

transmit these generated APs

Contractile Myocardial Cells Size

samll (0.2mm wide x 0.1 mm long)

bifurcate

single centrally located nucleus

Contractile Myocardial Cells

aerobic

high in myoglobin and mitochondria

extensive blood supply

involuntary

Characteristics of Cardiac Muscles Similar to Skeletal Muscles

striated

contain sarcomeres

Characteristics of Cardiac Muscles Unlike Skeletal Muscles

have shor, wide T tubules

less SR with no terminal cisternae

under SNS and PNS control

single nucleus

have intercalated discs to connect cells

Intercalated Disks

special structures between cardiac cells

Intercalated Disks Contain

gap junctions and desmosomes

Gap Junctions

connect adjacent cardiocytes

cardiac muscle cells as a functional organ

resembles “single unit” smooth muscle

direct connection (ions pass directly between cells)

Desmosomes

provide the ‘glue’ that holds the cell together → keep close contact

links proteins binding adjacent cells

allow chemical communication

resist mechanical stress

SA Node (Sinoatrial Node)

fires about 70 impulses/min

heart beat starts here (sets HR)

pacemaker of the heart

AV Node (Artioventricular Node)

fires about 50 impulses/min

delays the conduction from atria to ventricle

backup system

Conduction Fibers of the Myocardium

transmit AP’s quickly via

• intermodal pathways (atria)

• bundle of His (ventricles)

• Purkinjie fibers (ventricles)

they coordinate timing of heart contractions

What Does Conduction Cycle Depend on

the spread of excitation (APs) between cells

One Cardiac Cylce is a

coordinated event (atria contract first, then ventricles contract)

Coordination is Due to

presence of gap junction and conduction pathways