adbio cardiovascular

Cardiovascular system

-organ system that distributes blood to all parts ofthe body
-Major function - transportation, using blood as the transport vehicle

This system ___,__,___ hormones and other substances vital for body homeostasis to and form cells

carries oxygen, nutrients, cell wastes

The force to move blood around the body is provided by the ___.

The force to move blood around the body is provided by the pumping heart and blood pressure

size and weight of human heart

The human heart is approximately the size of a fist, and weighs less than a pound

It is enclosed within the __, the medial cavity of the thorax, and flanked on each side by the lungs

inferior mediastinum

apex is directed towards where

The pointed apex is directed toward the left hip

apex rests where

rests at about the fifth intercostal space

the broad aspect or base is directed towards where

points toward the right shoulder

the base lies where

lies beneath the second rib

pericardium

The heart is enclosed by a double-walled sac called the

fibrous pericardium

-The superficial loosely fitted part is called the fibrous pericardium
-Protects and anchors the heart

two-layer serous pericardium

Deep to the fibrous pericardium is the slippery,

parietal layer

-lines the interior of the fibrous pericardium
-attaches to the large arteries leaving the heart and then makes a U-turn and continues inferiorly over the heart surface as the visceral layer, or epicardium

serous pericardial membranes

-produces A slippery lubricating fluid
-which allows the heart to beat easily in a relative frictionless environment

pericarditis

-Inflammation of the pericardium often results in a decrease in the serous fluid
-The cause the pericardial layers to stick, forming painful adhesions that interfere with heart movements

1. outer epicardium 2. myocardium 3. endocardium

The heart walls are composed of three layers:

myocardium

• consists of thick bundles of the cardiac muscle twisted into ringlike arrangements

• This is the layer of the heart that actually contracts.

• Reinforced by dense, fibrous connective tissue ("heart skeleton")

endocardium

• is a thin, glistening sheet of endothelium that lines the heart chambers

• Continuous with the linings of the blood vessels leaving and entering the heart

2 atria - receiving chambers 2 ventricles - filling chambers

The heart has four hollow chambers:

2 atria

receiving chambers

2 ventricles

filling chambers

blood flow

Blood flows into the atria under low pressure from the veins, and continues into the ventricles

ventricles

• thickwalled discharging chambers

• They are the pumps of the heart

• When they contract, blood is propelled out of the heart and into circulation

right venrticle

forms most of the heart's anterior surface

left venrticle

forms the apеx

septum

divides the heart

interventricular septum

divides the heart longitudinally

interatrial septum

based on the chambers it separates

first process

• The heart functions as a double pump

• The right side works as the pulmonary circuit pump .

• Receives relatively oxygen-poor blood from the veins of the body through the large superior and inferior vena Superior cavae

seconf process

• The blood then pumps out through the pulmonary trunk which splits into the left and right pulmonary arteries

• The pulmonary arteries carry blood to the lungs, where oxygen is picked up and carbon dioxide is unloaded

pulmonary circulation (3rd prcoess)

• Oxygen-rich blood drains from the lungs and is returned to the left side of the heart through the four pulmonary veins

• Its only function is to carry blood to the lungs for gas exchange and then return it to the heart

pulmonary circuit

fourth process

• Blood returned to the left side of the heart is pumped out of the heart into the aorta

• The systemic arteries branch from the aorta to supply the body tissues with blood

process starts again

• Oxygen-poor blood circulates from the tissues back to the right atrium via the systemic veins, which empty their blood into either the superior or inferior vena cava

systemic circulation

• This second circuit, from the left side of the heart through the body tissues and back to the right side of the heart

• It supplies oxygen and nutrient-rich blood to all body organs

left ventricle

• is the systemic pump that pumps blood over a much longer pathway through the body,

• its walls are thicker than those of the right ventricle It is a more powerful pump

The heart also has four valves:

• 2 that separate the atria from the ventricles

• 2 that separate the ventricles from their arteries

• All of these valves prevent back flow

The atrioventricular (AV) valves

between the atria and ventricles

On the left

bicuspid or mitral valve

On the right

tricuspid valve

chordae tendineae

valves are anchored by

hangs limply

When the heart is relaxed and blood is passively filling its chambers, the AV-valve flaps hangs ___ into the ventricles

the intraventricular pressure rises

As the ventricles contract, they press on the blood in their chamber,

The semilunar valves

guard the bases of the large arteries leaving the ventricular chambers

on the right

pulmonary valve

On the left

aortic valve

When the ventricles are contracting

these valves are forced open and flattened against the arterial walls

When the ventricles are relaxed

the blood flows back towards the heart

The coronary arteries

branch from the base of the aorta and encircle the heart in the coronary sulcus (AV groove) at the junction of the atria and ventricles

coronary sulcus (AV groove)

The coronary arteries branch from the base of the aorta and encircle the heart in the ___ at the junction of the atria and ventricles

compressed

The coronary arteries and their major branches are ___ when the ventricles are contracting and fill when the heart is relaxed

angina pectoris

• When the heart beats rapidly the myocardium can received an inadequate amount of blood

• This can result in crushing chest pain

myocardial infarction

• "heart attack

• If angina is prolonged, oxygen-deprived heart cells may die forming an infarct

heart pumps

the body's 6 quart supply of blood through the blood vessels over 1000 times per day

600o quarts of blood

heart pumps about __ in a single day

spontaneously and independently

• Cardiac muscles cells can and do contract __, and __

• even if all nervous connections are severed These contractions occur in a regular and continuous way

Atrial cells

60 bpm

Ventricular cells

20-40 bpm

Autonomic nervous system

brakes and accelerator Acts to decrease or increase heart rate

Intrinsic conduction system (nodal system)

• Composed of specialized tissue that is a cross between muscle and nervous tissue

• Causes heart muscle depolarization from the atria to the ventricles

• Enforces contraction rate ~ 75bpm

Two systems act to regulate heart activity:

• Autonomic nervous system

• Intrinsic conduction system (nodal system)

septum

Intrinsic Conduction System

• The sinoatrial (SA) node is a crescent shaped node in the right atrium

• The atrioventricular (AV) node is at the junction of the atria and ventricles

• The atrioventricular (AV) bundle (bundle of His)

• Branch bundles in the interventricular septum

• Purkinje fibers which spread with the muscle of the ventricle walls

The sinoatrial (SA) node

crescent shaped node in the right atrium

The atrioventricular (AV) node

is at the junction of the atria and ventricles

Purkinje fibers

which spread with the muscle of the ventricle walls

SA node

• has the highest rate of depolarization in the whole system

• It starts each heartbeat and sets the pace for the whole heart and is therefore called the pacemaker

• The impulse travels from the SA node through the atria to the AV node, causing the atria to contract

AV node

• the impulse is delayed to give the atria time to finish contracting

• It then passes rapidly through the AV bundle, the bundle branches, and the Purkinje fibers, causing a "wringing" contraction of the ventricles that begins at the apex and moves toward the atria

• This contraction effectively ejects blood superiorly into the large arteries leaving the heart

Tachycardia

• is a rapid heart rate (> 100 bpm)

• but prolonged tachycardia may progress to fibrillation

Bradycardia

is a slow heart rate (< 60 bpm)

Fibrillation

• is a rapid, uncoordinated shuddering of the heart muscle

• makes the heart totally useless as a pump and is a major cause of death from heart attacks in adults

pacemaker

• is a small device, about the size of a half dollar piece, placed under the skin near the heart to help control the heartbeat.

• is implanted as part of what's often referred to as "cardiac resynchronization therapy."

Systole

• heart contraction

• atria contract simultaneously

diastole

• relaxation

• contraction of the ventricles begins

cardiac cycles

• refers to the events of one complete heartbeat, during which both atria and ventricles contract and then relax

average beats per minute

75 times per minute

o.8 seconds

average length of a cardiac cycle

The cardiac cycle occurs in three major steps:

1. mid-to-late diastole

2. ventricular systole

3. early diastole

Mid-to-late diastole

• The heart is in complete relaxation Pressure in the heart is low

• Blood is flowing passively into and through the atria and into the ventricles from pulmonary and systemic hovemetric

• Vent ontrastmw circulations A

• The semilunar valves are closed

• The AV valves are open

• Then the atria contract and force the blood into the ventricles

Ventricular systole

• The pressure within the ventricles increases rapidly, closing the AV valves

• When the intraventricular pressure is higher than the pressure in the large arteries leaving the heart, the semilunar valves are forced open, and blood rushes out of the ventricles

• The atria are relaxed, and again are filling with blood

Early diastole

• At the end of systole, the ventricles relax, the semilunar valves snap shut, and for a moment the ventricles are completely closed chambers

• During early diastole, the intraventricular pressure drops

• When it drops below the pressure in the atria, the AV valves are forced open. And the ventricles again begin to refill rapidly with blood

heart sounds

• When using a stethoscope, the heart beat usually has two distinct sounds - "lup" and "dup"

• These are caused by the closing of the two sets of valves

"lup"

AV sounds

"dup"

semilunar valves

blood vessels

create a closed transport system, or vascular system

• Higher, changing blood pressure

• Thicker walls The middle section (tunica media) is especially thick

• Strong and stretchy

capillaries

• minute blood vessels that connect arterioles and venules

• Form capillary beds

veins

• Lower, constant blood pressure

• Thinner walls Blood often flows against gravity

• Have valves

blood vessels

structure of blood vessel

1. tunica externa

2. tunica media

3. tunica interna

elastic arteries

• largest arteries in the body with large diameter

• consists more of elastic lamellae

• aorta, pulmonary trunk, branches of aorta

muscular arteries

• tunica media contains more smooth muscles and less elastic fibers

• capable of greater vasoconstriction and vasolidation for blood flow

• femoral arteries, axilary arteries

arterioles