Hour 1 Transport

8/12/2019 Hour 1 Transport

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Chapter 18

Transport System

Biology Unit (12/13)

Kedah MatriculationCollege


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Transport System

Chapter Review

animal plant

Blood

circulation

Lymphatic

system

Water

heart

structure

heart

beat

cardiac

cycle

Food

root

xylem

phloem


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At the end of the lesson, you should be

able to:

Explain the initiation of heart beat

and its control

Explain the factors affecting heart

beat


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Mammalian Heart

Structures and

function


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Mammalian Heart

Located behind the breastbone(sternum)

Cone-shaped

Consists mostly of cardiac muscle

Contracts and relaxes in a rhythmic

cycle :

contract, it pumps blood

relaxes, fill its chamber with blood


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Mammalian Heart

Anterior

vena cava

Right atrium

Pulmonary

vein

Semilunar

valveAtrioventricular

valve

Aorta

Pulmonary

artery

Left atrium

Pulmonary

veins

Rightventricle

Left

ventricle

Structure of Heart


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Superior vena cava Aorta

Inferiorvena cava

Pulmonary vein

Pulmonaryartery

Blood circulation

Vena cava right atria right ventricle pulmonary artery lung

Pulmonary vein left atria left ventricle aorta body tissues


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Contain 4 chambers:

Atrium(left and right)

- Thin- wall

- Serve as collection chambers for blood returning tothe heart

Left atrium:

- Receive oxygenated blood from the pulmonaryveins.

Right atrium:

- Receive deoxygenated blood from vena cavae.


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Ventricle (left and right)

- Thick- wall

- Pumps blood to all body organs

Left Ventricle- Pump blood to entire of the body

Right Ventricle- Pumps blood to the lung

- Less muscular


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Valves of the heart:

Prevent backflow of blood within the heart.

Atrioventricular valves (AV)

Tricuspid (right)

Bicuspid valve ( left)

Semilunar valves

Pulmonary semilunar valve (right)

Aortic semilunar valve (left)

Prevent backflow of

blood within the atria

Prevent backflow o

blood within theventricles


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Initiation of HeartBeat

Regulation of

nerves at heartwall


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Components involved in heart beats

1. Sinoatrial

node

(SA node)

2.Atrioventricular

node(AV node)

3. Bundle

branches

4.Purkinje

fibres

In the wallof rightatrium


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Initiation of Heart Beat Cardiac muscle are self-excitable

(myogenic)

contract without any signal from the

nervous system.

1) Sinoatrial (SA) node

Sinoatrial(SA) node, or pacemaker,

which sets the rate and timing at which

all cardiac muscle cells contract.

The SA node is located in the wall of the

right atrium.


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Initiation of Heart Beat

1.SA nodegenerateselectrical

impulses

Spread rapidly

through thewall of the atria

Making them

contract


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3. Impulse from theAV node areconducted to

heart apex bybundle branchesand Purkinje

fibers


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4. Impulse are conductedby Purkinje fibers

through out ventricular

walls.

- Stimulates the

ventricles to contract

from the apex

towards atria- driving blood into the

aorta & pulmonary

arteries.


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AV node

Purkinje fibers

Heart Apex

Contraction

of right

ventricles

Contractionof left

ventricle

SA node (pacemaker)

Wall of right atrium & wall of left atrium(atria contract)

SUMMARY

Delay for 0.1 sec

until atria empty completely

and

Bundle branches


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SA node (right atrium) Atria Wall (Atria Contract) delayed (AV

node) blood in atria empties into ventricles bundles branches

and Purkinje Fibers conduct signal heart apex ventricle wall

ventricles contract


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Control of Heart BeatHeart rate is controlled by two factors :

Nervous control(autonomic)

Hormonal control

Sympathetic Parasympathetic

Epinephrine &Norepinephrine

Increase heartrate during stress

Increase heart

rate

Decrease heart

rate

& thyroxine


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Factors affecting heart beat

pH


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Factors affecting heart Beat

Increasing of body temperature increase theheart beat.

Increasing 1oC will increase heart beat (10times/minute)

Lowering the body temperature (hypothermia)decreased the heart beat.

Body Temperature


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Depending on the temperature relative to the

body,

blood vessels will either dilate or contract.

If temperature increase, blood vessels dilate

(releases heat), blood pressure will decrease

to keep blood pressure stable, the heart has

to pump faster

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