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Chapter 9

The Mamalian

Heart

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Structure

Shape: Cone (apex pointed left)

Size: Fist

Mass: 300-500g

Location: Thoracic cavity (left) *except Dextrocardia

Enveloped in pericardium

Muscle: Myocardium (Cardiac muscle) joined by intercalated discs

for rapid nerve Impulse transmission. Mamalian heart Notes.doc

MyogenicSelf-excitable (Contract and relax naturally

without nerve stimulation)

http://c/Documents%20and%20Settings/kfsharon/My%20Documents/Personal/CV/KBU%20College/Mamalian%20heart%20Notes.dochttp://c/Documents%20and%20Settings/kfsharon/My%20Documents/Personal/CV/KBU%20College/Mamalian%20heart%20Notes.dochttp://beakstreetblog.com/2011/09/glassworks-map-of-the-human-heart/

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Structure

Right atrium

Left atrium

Right ventricle

Left

ventricle

Atria wall Ventricle wall Reason

Thinner Thicker Ventricle pumps blood out of heart to lungs

and whole body.

Atria pumps to ventricles.

Right ventricle

Thinner

Left

ventricle

Thicker

Left ventricle- pumps to whole body

Right ventriclepumps to lungs only

Chambers:

2 atrium - receives blood from vein

2 ventricles - pumps blood out of the

heart into arteries

Septum

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Structure Valves:

Atrio-ventricular valve-i) Tricuspid

ii) Bicuspid

(Mitral)

Semilunar valves- i) at Aorta entrance(Aortic valve)

ii) at Pulmonary

artery entrance

(Pulmonary valve)

Function: One direction flow from..to,

prevent backflow

Vessels:

Vena Cava

Pulmonary artery

Pulmonary veinAorta

Carotid arteries:

- surface

- nutrients for myocardium

Aorta Pulmonary artery

Pulmonary vein

Semilunar

valve

Semilunar

valveTricuspid

valve

Bicuspid

valve

Vena Cava

(Superior)

Vena Cava

(Inferior)

Circulations:

i) Pulmonary circulation

ii) Systemic circulation

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1: AV valve close 3: SL valve close

2: SL valve open 4: AV valve open

Cardiac Cycle

1) Atrial systole

- Atria wall contract

- Atrial pressure high, forces blood

through AV valves into ventricles

- SL valve closes dub

2) Ventricular systole

- After 0.1 second, last for 0.3seconds

- Ventricles contract

- Ventricular pressure muchhigher, forces blood through SL valves

out of the ventricles

-AV valves close lup

3) Ventricular diastole

- Atria and ventricles relax

- Heart pressure drops

- SL valves close- Blood from vena cava fills atrium

Sequence of events that makes one heart beat

http://www.karenmcarthur.com/samples/medIll/heart_fills.html

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Control of the Heart BeatPacemakers:

Specialized cardiac muscle cells that initiate

and coordinates rhythmic heart beat.

i) SAN (Sinoatrial Node)ii) AVN (atrioventricular Node)

iii) Purkyne Tissues (Bundle of Hiss,branches)

Heart beat rate: 70 times per minute

(average) =>pulse

Non-conductive fibres between AV

Purkyne tissues

-rapid transmission between septum

outwards upwards ventricle walls

- Ventricles contract bottom up

Heart sound

http://www.brooksidepress.org/Products/Military_OBGYN/Textbook/GynecologicExam/HeartExam/Heart3.jpg

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Electrocardiogram

Electrodes10

Graph of electrical potential generated and

recorded against time

P: Atria contraction (depolarization)

Q, R, S: Ventricular contraction

Atria relaxation (repolarization)

T: Ventricular relaxation

Electrocardiograph

http://www.aboutkidshealth.ca/En/HowTheBodyWorks/IntroductiontotheHeart/TheHeartbeat/Pages/ElectrocardiogramECG.aspx

http://www.nhlbi.nih.gov/health/health-topics/animate/flash-electrical.swf

http://www.practicalclinicalskills.com/ekg-lesson.aspx?coursecaseorder=6&courseid=301

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