chapter 18 - transport system (part 1)

7/30/2019 Chapter 18 - Transport System (Part 1)

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TRANSPORT SYSTEM

Powerpoint@lecture Slides Are Prepared By Biology Lecturer, KMPk
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18.1:

MAMMALIAN

HEART AND

ITS REGULATION


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At the end of this topic, students should be able to:

a. explain the initiation of heart beat and its

control.


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Structure of Heart

The internal cavity of the

heart divided into 4

chambers:

Right atrium

Right ventricle

Left atriumLeft ventricle


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Structure of Heart

Right atrium

receives deoxygenated

blood fromsystemic veins

Left atrium

receives oxygenatedblood from the

pulmonary veins


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Structure of Heart

Right ventricles passed

deoxygenated blood

through pulmonary artery

to lung for gases exchange

Left ventricles passed

oxygenated blood through

aorta to all body tissues


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Pulmonary (lung) circuit:

The right ventricle pumps

blood to the lungs viathe pulmonary arteries.

Blood in capillaries loads

O2 and unloads CO2.

Oxygenated blood returnsvia pulmonary veins to

the left atrium and left

ventricle.

Mammalian

cardiovascular system


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Systemic circuit:

Oxygenated blood leaves the

heart via the aortato capillaries in the head and

arms, and also to capillaries in

the abdominal organs and legs.

Oxygen-poorblood returnsvia superiorvena cava

and inferiorvena cava, then

empty into the right atrium.

Mammalian

cardiovascular system


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Path of Blood

Oxygenated blood

Left atrium

Left ventricle

Left ventricle

Body tissues

Systemic

Circulation

Pulmonary

Circulation

Via pulmonary

vein

Through AV valve

Via aorta

Deoxygenated blood

Right atrium

Right ventricle

lungs

Via superior

vena cava

Through AV valve

Via pulmonary

artery


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Initiation of Heart Beat

The cardiac muscle is

myogenic

Contracts and relaxesautomatically

Dont need nerve

stimulation


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Sinoatrial Node (SA)/

pacemaker:

Located at right atrium, near

opening of vena cava

Act as a pacemaker.

Initiates generation of impulse

Atrioventricular Node (AV):

Located in the right atrium



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Spread rapidly through the wall

of atria. Contract unison


1

SA node stimulate heart

contraction on its own

2

Passed to AV node

3

impuls

impuls

Delayed 0.1s

impuls

4


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Spreading to the ventricular walls

towards the heart apex.

- Conduct by bundle of His and

Purkinje fibres


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Ensures the atria empty

completely

6

Forcing blood into the pulmonary

arteries and aorta

5

impuls

Ventricles contract


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Control of Heart Rate

Action of SAN (pacemaker)

modified according to the

needs of the body

Examples: Action of SAN

increased during physical

activity


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Heart control centre (in

medulla oblongata)

The sympathetic nervestimulates an increase in

heart rate

The vagus nerve stimulatesa decrease in heart rate


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In cardiovascular centre,

there two region that

control the heart rate

cardiac inhibitory centre

cardiac acceleratory

centre


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To increase heart beat

Impulse from cardioacceleratory

center (sympathetic)

are sent via

sympathetic cardiac nerves

Released noradrenaline

Increase the rate of impulseproduction by SAN and AVN

Increase heart rate


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To slow down heart beat

Impulse from cardioinhibitorycenter (parasympathetic)

Are sent via parasympathetic

nerve (vagus nerve)

Released acetylcholine

Inhibit the production of impulses

by SAN and AVN

Slow down heart rate


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Initiation ofHeart Beat

1 2

3

56

4


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Question

The heart of a normally developing human fetus

has a hole between the left and the right atria. In

some cases, this hole does not close completely

before birth. If the hole werent surgically corrected,how it would affect the O2 content of blood entering

the systemic circuit?

The O2 content would be abnormally low because

some oxygen-depleted blood returned to the right

atrium from systemic circuit would mix with the

oxygen-rich blood in the left atrium.


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The oxygen content would be abnormally low

because some oxygen-depleted blood returned to

the right atrium from systemic circuit would mix

with the oxygen-rich blood in the left atrium.


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Cardiac cycle.

Factors affecting

heart beat.

chapter 18 - transport system (part 1)

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