The Circulatory System

Chapter 18-19

The Heart

-Size of your fist -In thoracic cavity between lungs-Rests on diaphragm

Structure

-hollow, cone-shaped -enclosed in pericardium (fibrous membrane)

PericardiumVisceral pericardium (epicardium)-layer of pericardium that is in contact with the heart

Parietal Pericardium -outer layer of pericardial sac

Paricardial Cavity -layer between visceral and parietal, contains serous fluid to help reduce friction

Pericarditis – inflammation of pericardium-caused by bacterial or viral infections -layers stick together and interfere w/ heart movements

Wall of Heart

Epicardium – protective layer -connective tissue covered by epithelium

Myocardium – thick layer of cardiac muscle-richly supplied with blood

Wall of Heart

Endocardium – consists of epithelium and connective tissue

-many elastic and collagenous fibers

Chambers and Valves

The heart has 4 chambers : 2 left, 2 right

Atria (Atrium) – upper chambers -thinner walls-receive blood from veins, or returning to the heart

Ventricles – lower chambers that pump blood through arteries to the rest of the body.

-thicker muscle or wall b/c they pump blood further

Septum – separates the right and left sides.

Chambers and Valves

Right Side of Heart

-Right atrium receives blood from superior vena cava, inferior vena cava, and coronary sinus

-Tricuspid valve guards opening between R. ventricle(chordae tendineae) and R. atria

-Right ventricle pumps blood to the lungs -thinner muscular wall than left ventricle

Chordae tendinae -orignates from the sm muscle tissue (papillary muscles) and projects inward from the walls of the ventricle.

Left side of Heart

-Left atrium receives blood from the lungs through 4 pulmonary veins

-Bicuspid (mitral) valve guards opening between L. atriumand L. ventricle

-Left ventricle pumps blood to the rest of the body through the aorta. The R and Lcoronary arteries branch off of the aorta tosupply the heart muscle.

-thick muscular wall -aortic valve (semilunar valve) preventsblood from flowing back into heart

Pathway of Blood

Right side receives blood lowin O2 and high in CO2

Right ventricle pumps blood to the lungs (pulmonary circuit)

Left side receives blood from Lungs: high in O2 and low inCO2

http://www.medtropolis.com/VBody.asp

http://www.pbs.org/wgbh/nova/heart/heartmap.html

Heart Blood Flow1. From superior and inferior vena cava2. Into the R. atrium3. Past the tricuspid valve into the R. ventricle 4. Through the semilunar valve into the pulmonary artery to the lungs 5. From the lungs through the pulmonary veins into the L. atrium6. Through the bicuspid valve (mitral) into the L. ventricle 7. From the L. ventricle past the semilunar valve to the aorta 8. Blood is transported to the body through arteries, arterioles, and capillaries.9. Venous blood travels back through venules and then veins

O2 poor bloodO2 rich

Blood Supply to Heart/Coronary Circulation

-Heart needs a steady supply of oxygenated blood-Right and left coronary arteries branch off of aorta andsupply blood to the muscle cells of the heart-Coronary sinus empties into R. atrium (carries venous blood)

http://www.bidmc.org/YourHealth/ProceduresInMotion.aspx

Angina – severe chest pain Ischemia – reduced blood flow to tissue

Coronary Artery Disease (CAD) – reduced blood flow to myocardial tissue due to clogged or blocked arteries.

1. Atherosclerosis – hardening of arteries, calcifying of lipids in blood vessels making them hard and brittle.

2. Myocardial infarction – tissue death often leads to heart attack b/c blood clot or clogged.

Treatments – angioplasty, stents, bypass surgery

http://www.hhmi.org/biointeractive/stemcells/video.html

http://www.heartinfo.org/ms/animations/13/main.html

http://www.nhlbi.nih.gov/health/health-topics/topics/heartattack/causes.html

Heart Attack, Cholesterol, Laser Angioplasty

http://www.hhmi.org/biointeractive/media/heart_attack-lg.mov

http://health.india.com/diseases-conditions/what-is-a-heart-attack-animation/

http://wn.kktv.com/category/60673/medical-3d-animation-heart-attack

Heart Sounds (Dub – Dub)

Lubb = 1st part of sound (systolic)-ventricles contract…empty-tricuspid and bicuspid valves close (A-V valves)

Dupp = 2nd part of sound (diastolic)-ventricles relax…fill-pulmonary and aortic semi-lunar valves close

*Heart murmurs – abnormal sounds that may indicate problems with valves

Cardiac Cycle

Cardiac cycle = one complete heartbeat

-Takes about .8 seconds -The atria contract while the ventricles relax-Ventricles contract while atria relax

R. Ventricle lungs L. Ventricle body

Cardiac Cycle Cont.

Sinoatrial Node (SA Node)

-Small mass of tissue that stimulates contractions in the heart (interatrial fibers stimulate the left atria)-Called the pacemaker of the heart -Responsible for the rhythmic contractions -Stimulates atria to contract

p565 Fig 18-11, p595 Fig 19-1

Atrioventricular node – (AV Node)

-Specialized muscle tissue in the floor of the R. Atrium

-Internodal fibers connect the SA Node to the AV Node

-Delayed impulse allows the atriato empty and ventricles to refill.

-As impulse travels through the AV bundle (bundle of His) the impulse travels more rapidly

Cardiac Cycle Cont.

-Purkinje fibers: function in transmitting the impulse from the AV bundle to ventricular muscles to contract and force the blood into the arteries

-The Purkinje fibers stimulate the papillary muscles

Cardiac Cycle Cont.

Electrocardiogram (ECG)

-A recording of electrical chgs occuring within the heart

-Electrodes placed on the skin and connected by wires

-A pen records any electrical changes

P Wave – depolarization of atria… “atrial contraction”QRS – depolarization of ventricles and atrial repolarization

“ventricular contraction”T Wave – repolarization of ventricleshttp://www.getbodysmart.com/ap/circulatorysystem/heart/electricalevents/ecg/tutorial.html

http://www.ecgrhythmcourse.com/look_inside.cfm

P599 Fig 19-4

Regulation of Cardiac Cycle

-Parasympathetic fibers secrete acetylcholine-slows down heart, dec rate of contractions

-Sympathetic fibers secrete norepinephrine -increases rate of contractions

-Cardiac center is located in medulla oblongata-receives sensory info from various parts of circulatory system -responds to anxiety, fainting, temp change, ionconcentration (K+, Ca+2)

Blood Vessels

Arteries – strong, elastic vessels that carry oxygenated blood away from heart under high pressure…exception p. artery

-thick walls-arterioles : small arteries that join to capillaries

Vasoconstriction – muscle fibers contract and decrease vessel diameter

Vasodilation – muscle fibers relax and increase vessel diameter

Both tunica media and tunica adventitia are absent in veins and capillaries

Blood VesselsVenules & Veins

Veins – deoxygenated blood to the heart..exception p. veins *thinner walls *blood reservoir *low pressure

Venules – small veins, that join to capillaries.

Sinuses - lg venous spaces

Blood VesselsCapillaries -microscopic vessels that carry blood from arterioles to venules*thin endothelium- allows for ease of transport across membranes

*Blood pressure dec as the distance from the heart inc.

Blood Pressure -The force blood exerts against the inner walls of blood vessels

Systolic pressure - maximum pressure achieved during ventricular contraction (arterial pressure). (pressure while heart is beating)

Diastolic pressure - the lowest pressure that remains in thearteries before the next ventricular contraction. (resting stage between beats)

Ventricles are filling up/relaxed

Ventricles are emptying/contracting

Normal

Prehypertension

Hypertension

120 Systolic 80 Diastolic

120-139 80-89

140 or more 90

Pulse pressure = diff between systolic and diastolic pressures

Congestive heart failure – (left side failure) left ventricle decreases pumping pressure in systemic circulation which then causes fluid tobuild up

Cardiomyopathy - is a weakening of the heart muscle or a change in heart muscle structure. It is often associated with inadequateheart pumping or other heart function abnormalities.

Congenital heart disease - Congenital heart disease refers to a problem with the heart's structure and function due to abnormalheart development

Aneursym – is a bulge or ballooning of the artery which can grow and burst and possibly cause death.

Babe – “Demented” possibly TOURETTS

Lafawnda

Ethel – “Spacy”

ELLE – THE BOSS!!!

“The bestbehaved”

Pork chopLunch!!

Wilber – “Whity / asian”

Phil – “The Butcher’s son”

Geogina – “Whatever”

The green runtMoo

Don’t forget to wish you motherHappy Mother’s Day

on Sunday!!!