Transcript Introduction to the circulatory system

Introduction to the
circulatory system
Aims of the seminar
Recap on previous seminar ‘the muscle fibres
in the body’.
 To introduce the term ‘circulatory system’.
 To give a detailed explanation of the
structure and functions of the circulatory
system.
 To examine the direction of blood flow
through the heart.
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Muscle Fibre Types
Muscles are composed of thousands and
thousands of individual muscle fibres
 Not all fibres are alike in structure and
function
 Can be classified into 3 types:
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Type I
Type IIA
Type IIB
Type I Fibres
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Slow twitch or slow oxidative fibres:
Red in colour
Large amounts of mitochondria, myoglobin
and capillary network
Work slowly (split ATP at a slow rate)
Able to repeatedly contract or maintain
contraction for a long duration
High resistance to fatigue
Fibres work mainly aerobically
Type IIA Fibres
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Fast twitch or fast oxidative glycolytic fibres
(FOG)
Similar to Type I Fibres
Red in colour
Large amounts of myoglobin, many
mitochondria and capillaries
Resistant to fatigue
Work rapidly to split ATP, fast contraction
speed
Work aerobically or anaerobically
Used in high intensity, short duration activities
such as 200m swim or 800m
Type IIB Fibres
Fast twitch or fast twitch glycolytic (FTG) fibres
White in colour
Low number of myoglobin, few mitochondria, few
capillaries
 Fatigue easily
 Fast contraction speed, split ATP quickly
 Much stronger force of muscle contraction
 These are used for activities of a very high intensity
(anaerobic)
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e.g. powerlifting or 100m sprint
Fibre Mix
Most skeletal muscle is a mixture of all
3 types
 Proportion of types varies in relation to
usual action of the muscle
 For example – the postural muscles of
the neck and back and leg have a
higher proportion of Type I Fibres
 Why do you think this is?
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The function of the circulatory
system
The circulatory system has three major
function:
 Transport
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Body temperature control
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Moving things around the body in the blood stream such
as oxygen and nutrients like glucose.
Thermoregulation, moving blood near the skin cools
down the body. That’s why you look redder when you
exercise heavily.
Protection
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Moving anti-bodies around the body fighting diseases
and clotting cuts.
The structure of the heart
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Oxygenated blood has
more oxygen and is
found in the arteries
(except in the
pulmonary artery).
Deoxygenated blood
has less oxygen and is
found in the veins
(except in the
pulmonary vein.)
The cardiovascular system:
HEART
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The heart
Situated in the left-hand side of the chest
Muscular pump whose purpose is to drive the
blood into and through the arteries, to deliver
it to the tissues and working muscles
Considered as two separate pumps
Two chambers on the right, and two
chambers on the left side
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What are they?
The cardiovascular system:
HEART
Structure of the Heart
 Surrounded by sac known as the pericardium,
which prevents friction as the heart beats.
 Heart wall is made of:
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Epicardium (outer layer)
Myocardium (strong middle layer)
Endocardium (inner layer)
Right separated from left by Septum
Strokes of the heart
Heart rate per minute is how many time
the heart beats in one minute.
 Stroke volume is the amount of blood
pumped from the heart per beat.
 Cardiac output is the amount of blood
pumped from the heart in one minute.
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Cardiac output = Stroke volume + Heart
rate
Double circulation
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Every time the blood goes around the
body it goes through the heart twice,
this is known as a double circulation.
Circuits of the body
There are two circuits of the body you need
to know:
 Systemic
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The main circuit of the body, it carries oxygenated blood
around the body through arteries.
It carries deoxygenated blood back to the heart and
lungs through veins to be deoxygenated in the
pulmonary system.
Pulmonary
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Consists of the heart and lungs, deoxygenated from the
heart to the lungs to be oxygenated. The oxygenated
blood then goes back to the heart to be pumped around
the body.
The flow of blood through the heart
and around the body.
Blood Flow Through the Heart
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Vena Cava – Superior/Inferior
Right Atrium
Tricuspid Valve
Right ventricle
Pulmonary Artery
LUNGS
Blood Flow Through the Heart
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Pulmonary veins
Left Atrium
Bicuspid/Mitral/Atrioventricular valve
Left Ventricle
Aorta
MAJOR ORGANS
The Heart
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Made of cardiac muscle (myocardium)
Has it’s own blood supply
Two upper thin walled chambers – atria
Two lower thick walled chambers – ventricles
Atria collect blood from the body – attached
to veins
Ventricles send blood to the body – attached
to arteries
The Heart
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Right side – deoxygenated
Left side – oxygenated
Separated by a thick walled septum
Right atrium and ventricle connected by
tricuspid valve
Left atrium and ventricle connected by
bicuspid (mitral) valve
Cuspid valves held shut by Chordae Tendinae
Left ventricle is thicker than the right
Vessels of the Heart
Pulmonary artery*
 Pulmonary vein
 Superior and Inferior Vena cava
 Aorta*
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*Semi-lunar valves
Control of the Heart
Myogenic-Initiated from inside the heart
as opposed to nervous stimulus outside
 Initial Stimulus originates in the
Sinoatrial node (SA node)
 Pacemaker determines heart rate
 Wave of excitation across both atria
causes them to contract
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Control of the Heart
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Sinoventricular node (SV node)
Sends waves of excitation along Purkinje
Fibres which collectively make up the Bundle
of Hiss. Along septum, radiate upwards
Ventricles contract
Both atria and both ventricles contract at the
same time
Systole-contraction of heart
Diastole-Relaxation/filling of the heart
Next Seminar
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Introduction of valves that Transport
the blood through the body.