Download M2 L6 - Circulatory system

Circulatory system
page 40-49
Southend Personal Trainer Academy
The function, location and structure of
the heart (page 40)
u
It is located just behind the sternum, just left of centre
u
The heart is a muscular pump which pushes blood around the body, the blood
will contain oxygen and nutrients which is delivered to the body
u
The heart is made up of four muscular chambers called atria and ventricles
u
The heart muscle is called cardiac muscle
u
Right half of the heart – receives blood from the body and pumps blood to the
lungs
u
Left half of the heart – receives blood from the lungs and pumps blood to the
body
Heart diagram (page 41)
Route of blood (page 41)
u
Vena cava(e) – oxygen poor blood from the body
u
Right atrium
u
Right ventricle
u
Pulmonary artery – oxygen poor blood to the lungs
u
Gaseous exchange at the lungs
u
Pulmonary vein – oxygen rich blood from the lungs
u
Left atrium
u
Left ventricle
u
Aorta – Oxygen rich blood to the body
Heart rate (page 40)
u
Heart rate is controlled by the sinoatrial (SA) node
u
The SA node is located in the wall of the right atrium
u
The myocardium (heart muscle) is stimulated to contract about 72 times per
minute by the SA node as part of the autonomic nervous system
Heart valves (page 41)
u
Atrioventricular valves separate the atria and ventricles and prevent backflow
of blood into the atrium
u
The semilunar valves prevent the flow of blood back into the right and left
ventricles
Systemic and pulmonary circulation
(page 42)
u
Pulmonary circulation – this is the circulation between the heart and lungs
u
Systemic circulation – this is the circulation between the heart and the body
Function of blood vessels (page 43)
u
Blood vessels are the transport system for blood
u
They carry the blood from the heart to the body and back again
u
Blood carries nutrients and oxygen to all cells in the body
u
It also removes waste products and carbon dioxide
Components of blood (page 43)
u
Red blood cells – contains haemoglobin that allows the transportation of
oxygen
u
White blood cells – these help to fight infection
u
Platelets – aids clotting and prevents blood loss
u
Plasma – plasma is the fluid portion of the blood
Structure of blood vessels (page 43)
u
Arteries – muscular tubes with thick walls which can contract to squeeze blood
along (called peristalsis), these divide into arterioles.
They also contain no valves unlike veins
u
Capillaries– have extremely thin walls (one cell thick) and spread to all parts of
the body.
They are thin to allows oxygen and nutrients into cells
u
Veins – Peristalsis helps to return blood to the heart, they have thinner walls than
arteries with less contractility
All veins have valves to prevent blood flowing backwards on its way to the heart,
as veins carry blood under low pressure unlike arteries
Control of circulatory blood flow (page
45)
Venous return and blood pooling (page
46)
u
Venous return – the flow of blood back to the heart via a networks of veins
u
Contributing factors
1.
Gravity – assists blood anywhere above the heart
2.
Skeletal muscle contraction – squeezing action of muscles help assist blood flow
3.
Non return valves – prevent the backflow of blood
4.
The diaphragm – helps with a suction effect on veins below the heart
5.
Right atrium – helps to suck the blood back due to a vacuum effect
Blood pressure (page 46)
u
Blood pressure is a measure of the force that the blood applies to the artery
walls
u
Blood pressure is expressed as two numbers such as 120/80
u
The top number is the systolic and is the higher number of the two, this is the
measure of pressure exerted when the myocardium contracts
u
The bottom number is the diastolic and this is the measure of pressure when
the myocardium is relaxed
Blood pressure classifications (page 47)
Category
Systolic
Diastolic
Low
<100
<60
Optimal
<120
<80
Normal
<130
<85
High normal – Prehypertension
130-139
85-89
Stage 1 Hypertension
140-159
90-99
Stage 2 Hypertension
160-179
100-109
Stage 3 Hypertension
>180
>110
Effects of exercise on BP (page 48)
Short term
u
Increase in systolic blood pressure
u
Diastolic may remain unchanged or slightly increase
u
Heavy weight training and isometric exercises will increase both systolic and
diastolic blood pressure
Long term
u
Long term aerobic exercise can be used to reduce blood pressure
Effect of exercise on the circulatory and
CV system (page 48)
Short term
Long term
Increases in heart rate
Stronger myocardium
Increases in stroke volume
Lower resting heart rate
Increases in cardiac output
Increase in stroke volume (per beat)
Increases in systolic blood pressure
Increased cardiac output (1 minute)
Dilation of capillaries
Increase in size and number of
mitochondria
Increase in number of capillaries
Sustained optimal blood pressure