The Circulatory SystemThe Circulatory System(complete Info. Ppt)(complete Info. Ppt)

By- Dr. Armaan singhBy- Dr. Armaan singh

Interesting Facts

The heart beat is strong enough to squirt blood 30 feet

The longer a boy’s ring finger is, the less likely they are to have a heart attack (according to one study)

The human heart beats ~35 million times per year

The heart pumps ~1,000,000 barrels of blood in a lifetime

Most heart attacks occur between 8-9 a.m.

Interesting Facts

The blue whale has the largest heart – it weighs ~ one ton

The hummingbird has a heart that beats 1000 times per minute

Your entire volume of blood goes through your entire body once every minute

Humans have ~60,000 miles of blood vessels in their bodies (more than twice the circumference of the earth!)

Your heart beats 100,000 times and pumps ~2000 gallons of blood every day

Pig and baboon hearts have been transplanted into humans

Cardiovascular System

Heart, vessels, blood

Function: transport gases, nutrients, wastes, hormones

The Heart

Size of a fist; less than a pound

In thorax; flanked by lungs; rests on diaphram

Top: base

Bottom: apex

Pericardium

Double-layered sac covering the heart

Outer layer anchors heart in chest

Inner layer (epicardium) attached to heart wall

Lubricating fluid in pericardial space (between layers) reduces friction

Pericarditis

Decrease in fluid causes layers to

cling & rub against each other resulting in pain & decreased efficiency of heart

Pericardial Tamponade

Bleeding into pericardial space after chest trauma

Excess blood restricts expansion of heart during pumping

Causes shock or death if not corrected

Heart Wall

3 layers:

Epicardium: outer wall joined with pericardium

Myocardium: the actual cardiac muscle that contracts

Endocardium: lines heart chambers & vessels

Heart Chambers

Four chambers:

2 atria: top of heart – receive blood from veins

2 ventricles: bottom of heart – pump blood through arteries

Heart Chambers

Septum: divides left from right heart

Valves: keep blood flowing in one direction

Four valves:

2 AV valves,

2 semilunar valves

Heart sounds (Lupp-dupp) from valves closing

Atrioventricular Valves

AV valves: between atria

and ventriclesBicuspid (mitral) valve:

on the leftTricuspid valve: on the

right

When valves are open blood drains from atria into ventricle

When ventricle contract, valve flaps are forced shut, blocking blood from reentering atria

Semilunar Valves

Located in arteries leaving

ventricles

Pulmonic valve: at base of

pulmonary artery

Aortic valve: at base of aorta

When ventricles contract, valves are forced open & let blood flow

When ventricle relaxes, backflow of blood fills flaps of valve & forces them to shut

Blood Vessels

Arteries: carry blood away from the heart

Veins: carry blood to the heart

Capillaries: connect arteries to veins & exchange gases with tissues

Arteries

Carry blood at high pressure

Very thick, stretchy walls that expand in size

Most carry oxygenated blood (red)

Damaged arteries spurt in time to heart beat

Arteries

Aorta: largest vessel (diameter of a garden hose) –receives blood from left ventricle

Arteriole: smaller vessels connecting arteries to capillaries

Veins

Carry blood at low pressure

Have valves to prevent backflow of blood against gravity

Most carry de-oxygenated blood (purple)

Damaged veins ooze blood

Veins

Vena Cava: dump all blood from the body into the right atria

superior vena cava: receives blood from upper body

inferior vena cava: receives blood from lower body

Venules: smaller vessels connecting veins to capillaries

Capillaries

Connect arteries and veins

Walls are one cell thick

Allow exchange of gases through thin walls Drop off oxygen delivered from heart by arteries

Pick up CO2 and send it to the heart thru veins

How Blood Travels thru Vessels

heart artery arteriole capillary venule vein heart

AtherosclerosisNarrowing of

vessel lumen due to plaque/fat formation on inside of walls

Causes: diet high in fat, cholesterol, salt; inactive lifestyle; smoking

Risks: high BP, enlarged heart, embolus blocking circulation; stroke

Coronary Artery Disease

When Atherosclerosis affects the arteries that supply the heart muscle

Symptoms: short of breath after simple exertion, angina (chest pain)

Risk: MI, cardiac arrest, death

How is CAD treated?

Medication

Angioplasty (balloon surgery) – balloon is inserted and inflated in blocked vessel to compress fatty mass against the artery wall

How is CAD Treated?

Stent – wire mesh inserted into the artery to expand its lumen

Coronary Artery Bypass – arteries are removed from leg and grafted into the heart to restore circulation

Vessel Disorders

Varicose Veins:

twisted, dilated veins resulting from pooling of blood due to long periods of standing, obesity, or

inactivity

Vessel Disorders

Thrombophlebitis:

inflammation of a vessel due to clot formation & poor

circulation. Clot can become an embolus if freed.

Aneurysm

Weaking in the wall of a vessel, causing it to balloon outwards.

Rupture of the site causes

Stroke (if in the brain)

Death (in a large artery – aorta).

Cardiac Circulation

Coronary arteries exit the aorta & supply oxygen/blood to heart muscle (myocardium)

Coronary veins pick up & return deoxygenated blood from myocardium

Defects in Coronary Circulation

Angina Pectoris: impaired circulation to myocardium causes oxygen deprivation & pain

Myocardial infarction: “heart attack” – blockage of circulation to section of myocardium causes the muscle to infarct (die)

Pulmonary Circulation

Right ventricle pumps deoxygenated blood through pulmonary artery to the lungs

The blood picks up O2 from the lungs and dumps CO2 into the lungs

Oxygenated blood is returned to the left atrium thru the pulmonary vein

Systemic CirculationOxygenated

blood is pumped from left ventricle thru aorta to the body

Blood dumps oxygen into tissues and picks up CO2

Deoxygenated blood travels from body to vena cava to the right atrium

The Circulation

Play the Game

Number the parts 1 – 17 (just write the correct order on a piece of paper). Pass your paper to a classmate when you finish. We will grade

them as a class.

Congestive Heart Failure

Heart is ‘worn out’ from hypertension, multiple MI, atherosclerosis, or age

Heart pumps too weakly to meet tissue needs

If one side is weaker than the other, blood will back up in system

Congestive Heart Failure

Left ventricle is failing: Pulmonary congestion

Pulmonary edema (blood in lungs) causes suffocation

Right ventricle is failing: Peripheral congestion

Edema in distal body parts (ankles, feet)

Pulmonary Edema

Pulmonary edema (A); normal lung

(B)

Peripheral Edema

Swelling of feet and ankles due to CHF

Conduction System of the Heart

Heart is under two types of control:

Autonomic Nervous system

Sympathetic: speeds up contractions

Parasympathetic: the “brakes” that slows down contractions

Intrinsic Conduction System

Also called “nodal system”

Heart determines its own rate of contractions

Intrinsic Conduction System

Nodes are heart tissue that

stimulate heart muscle to

depolarize (contract)

Depolarization moves from base to apex

Different areas of the heart have different nodes, each with a different rate

Node rate gets slower as it moves downwards

Faster nodes will override slower nodes

Nodes (you need to know these)

3 Stages:

SA node fires, atria contract (depolarize)

Impulse travels to AV node, then travels thru bundle of His, bundle branches, & Purkinje fibers – ventricles contract (depolarize)

Contraction of ventricles has ‘wringing’ action, pushing blood upward and out through large arteries

Heart muscle repolarizes

Parts of the Conduction System

SA node:

“The Heart’s Pacemaker”

In atria

Normally sets the pace of 60 – 70

SA can increase rate when stimulated by drugs, fever, or sympathetic NS (exercise, stress, emotion)

AV Node:

Between atria &

ventricles

Special tissues transmit signal from SA to AV node

Intrinsic rate: 40 - 60

Parts of the Conduction System

Bundle of His:

Transmits impulse to ventricles

Rate: 30 – 40 beats/min

Bundle Branches:

Within ventricular muscles

Rate: 20 – 30 beats/min

Purkinje fibers:

Terminal end of branches

What if Damage Occurs?

If SA node is damaged or its signal is blocked, the AV node takes over setting the pace (40-60/min)

If AV node is next damaged, the bundles set the rate (20 – 40/min)

What is a Pacemaker?

If heart is unable to generate impulse, or pace is too slow,

mechanical pacemaker is surgically implanted to

provide artificial impulses

Electrocardiogram (ECG/EKG)

Electrical impulses in heart are measured with ECG

Electrical activity is translated into waves

Electrocardiogram (ECG/EKG)

P Wave: atria depolarize

QRS complex: ventricles depolarize

T wave: repolarization

Abnormalities in ECG

Heart Monitor hooked up with pads on chest

Abnormalities in ECG used to diagnose heart damage

Diagnostic signs: changes in shape of wave, distance between waves, lack of waves…

Irregular Heart Rhythms

Tachycardia: heart is beating too fast

Bradycardia: heart is beating too slow

Heart Block: no connection between atria & ventricles – ventricles beat at their own rate

Ventricular Fibrillation: heart is ‘shivering’ – no contractions or pulse (cardiac arrest)

Asystole: dead heart – no electrical activity

Comparing Rates

Normal Sinus Rhythm

Sinus Bradycardia

Sinus Tachycardia

Elevated ST segment (sign of a MI)

Ventricular Tachycardia

Heart Block

PVC (premature ventricular fibrillation)

Ventricular Fibrillation

Asystole

Cardiac CycleCardiac Cycle: The events

within one heartbeat. Three main stages:

Mid-to-late diastole: SL valves are closed, AV open; atria contract; blood is forced into ventricles

Ventricular systole: ventricular pressure forces AV closed; SL forced open; blood rushes out of ventricles; atria relax & refill

Early diastole: SL shut; AV open; ventricles relax and refill passively

Heart Sounds

Cardiac cycle heard with a stethoscope

Two sounds: “lub dup” (pause) “lub dup” (pause) …..

Lub = closing of AV valves (ventricular systole)

Dup = Closing of semilunar valves (between ventricular systole & diastole)

Murmurs: abnormal heart sounds that usually indicate valve problems

Valve Disorders

Leaky Valves: caused by incompetent or deformed valves that force the heart to re-pump blood because of backflow

Stenosis

Valves are stiff and do not open completely. Heart has to pump harder Murmur: stenosis

Mitral Valve Prolapse

The most common valve disorder

(5-10% of people)

Mitral valve opens (prolapses) into atrium when shutting & allows blood backflow

Cardiac Output

Cardiac Output: the amount of blood pumped by each side of the heart per minute

Cardiac output = heart rate X stroke volume

Stroke volume = the amount of blood pumped with each contraction

What is the cardiac output if….

HR = 75 bpm; SV = 70 ml/beat?

This is the normal cardiac output for a resting adult.

How is the output affected with exercise?

Do you think it increases or decreases?

What affects Stroke Volume?(you don’t have to write this down)

Increase in Stroke volume:

Increased venous blood return

exercise (muscles force blood into heart)

Slow hr (more time to fill ventricles)

Decrease in stroke volume

Decreased venous return

Hemorrhage (less blood volume)

Tachycardia (not enough time to fill)

What affects Heart Rate?(you don’t have to write this either)

Increase:

Decline in SV (heart compensates by hr)

Babies and kids

Females

During exercise

Sympathetic NS

Decrease:

Parasympathetic NS

Getting older

Males

Being fit (heart is more efficient)

Cold temperatures

Taken to assess overall health status

Arterial pulse

Blood Pressure

Respiratory Rate

Temperature

Arterial Pulse

Alternating expansion and recoil of arteries with each heart beat

Measured in beats per minute

Normal resting pulse: 60 – 100 bpm

Taken at pulse points: place where pulse is easily palpated (felt)

Pulse Points

Can also be used as pressure points to stop

bleeding

Blood Pressure

Pressure of the blood against artery wallsMeasured as systolic/diastolic (ex. 120/80)

Systolic: pressure at peak of contractionDiastolic: pressure during ventricular relaxation

Can be taken by:Auscultation (listening for pulse)Palpation (feeling for pulse)

Normal: 100 + age / 60-90

What Determines the BP?

Cardiac Output (blood pumped per min)

Peripheral Resistance

friction inside vessel that hampers flow of blood

Usually results from narrowing of arteries

What affects BP

Increases BP:

Atherosclerosis

Thick blood

Drugs/nicotine

Obesity

Decreases BP:

Shock/blood loss

MI

Drugs

Physical fitness

Problems with BP

Hypotension (low BP):

Systolic < 90mm/Hg

Cause: MI; warning sign of shock; athletes

Hypertension (high BP)

Systolic >140; Diastolic >90

Heart is forced to work hard for extended time

Vessels damaged due to higher pressure

Causes: obesity, diet, exercise, smoking, genes

Risks: heart attack, stroke