Download Task 1 – Cardiovascular

Laura Spenceley
Task 1 - Cardiovascular
Anatomy & Physiology
Function
The heart plays a unique role as an organ within the human body and has 5 main functions which are
outlined below:
1. Transporting Oxygen and Removing Carbon Dioxide One of the most important functions of the circulatory system is to supply oxygen to all the
cells in the body. Every cell in the body requires a constant supply of oxygen to stay alive.
Because most of the cells are not in contact with air, the circulatory system must supply
them with oxygen. When a person inhales, air enters the lungs, and oxygen is then absorbed
across the membrane of the lungs into the bloodstream. This oxygen-rich blood is pumped
through the heart to smaller and smaller blood vessels throughout the body. In the tiniest
blood vessels, called capillaries, oxygen diffuses out of blood and into cells. At the same
time, carbon dioxide produced by the cells is absorbed back into blood, which then returns
to the lungs, releases carbon dioxide and picks up more oxygen.
2. Transporting Nutrients and Removing Waste Materials –
A second critical function of the circulatory system is to supply all the cells in the body with
nutrients and energy. After food is digested in the stomach, it migrates through the
intestines, where nutrients from food are absorbed into the bloodstream. The blood also
absorbs glucose, an energy source, from the liver, which is the body's glucose distribution
centre. These nutrients and energy are then transported to all the cells of the body, in a
manner similar to the transport of oxygen. Blood also absorbs the waste products made by
cells, and transports them to the excretory organs for removal from the body.
3. Fighting Disease –
In addition to nutrients and oxygen, the blood also carries around important disease-fighting
cells. The organs of the immune system, such as the spleen, create many types of specialized
cells that can kill foreign cells trying to invade the body. The circulatory system is responsible
for transporting these cells from the immune system to all other parts of the body.
4. Transportation of Hormones –
Hormones are crucial chemical signals that the body uses to communicate with itself.
Hormones control many things such as growth, the reproductive cycle and glucose
metabolism. Hormones are created in one part of the body, such as the brain or the liver,
and then must be transported to another part of the body by the cardiovascular system in
order to deliver their message.
5. Regulation of Body Temperature –
The cardiovascular system also plays a role in regulating body temperature. If body
temperature rises too high, blood vessels close to the skin dilate, increasing in size. The
larger surface area of blood vessels close to the skin means more heat is conducted across
the skin into the air. Conversely, if body temperature drops, the blood vessels constrict,
decreasing in size. The smaller surface area of blood vessels next to the skin causes less heat
to be lost across the skin and retains more heat in the body.
Laura Spenceley
Task 1 - Cardiovascular
Anatomy & Physiology
Structure
The heart is a cardiac muscle which works involuntary. The heart is comprised of four chambers, the
upper chambers are known as the atria, which receive blood, the lower chambers are known as the
ventricles which expel blood into the arteries. There are four chambers separating the chambers:
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Tricuspid valve – separates right atrium from right ventricle
Pulmonary valve – separates the right ventricle from the pulmonary artery
Bicuspid valve – separates the left atrium from the left ventricle
Aortic valve – separates the left ventricle from the Aorta
The heart is composed of three layers:
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Epicardium – outer layer of the hearts tissue which gives it a smooth texture
Myocardium – the thick middle layer of cardiac muscle fibres which connect to electrical
synapses, responsible for the contraction and relaxation of atria and ventricles.
Endocardium – inner most layer of the heart which is composed of connective tissues and
lines the cavities and valves. The endocardium regulates contractions of the heart, aids
cardiac development and may regulate composition of blood which feeds the tissues of the
heart. The right side of the heart receives deoxygenated blood and the left side of the heart
receives oxygenated blood.
Vital Statistics - There are 2 main vital statistics which doctors and health professionals use to
assess the immediate health of your heart: blood pressure and pulse rate, as the condition
of your heart changes due to health or environmental factors these statistics will fluctuate
accordingly.
Blood pressure (BP) – is the pressure of blood in your arteries. To ensure blood is pumped
around the body
efficiently there
must be a certain
pressure of blood in
your arteries.
During different
stages of the
heartbeat cycle the
pressure of blood in
your arteries
changes. Blood
pressure readings
give off two
numbers, diastolic
and systolic
pressure. Systolic pressure is the top number when a BP is written and is the highest
pressure in your arteries when your heart contracts and pushes blood through your arteries.
Laura Spenceley
Task 1 - Cardiovascular
Anatomy & Physiology
Diastolic pressure, the bottom number when written, is the lowest level the blood in your
arteries reaches as your heart relaxes between contractions. The diagram above shows the
technique of taking blood pressure and how readings are taken. It is important to regularly
have your blood pressure taken if you are on medication, have a disease, condition or illness
which may affect your blood pressure and heart or are over a certain age. The average
blood pressure for healthy adults ranges from 90/60 to 140/90.
Pulse Rate - Your pulse is the rate at which your heart beats. Your pulse is usually called
your heart rate, which is the number of times your heart beats each minute (bpm). But the
rhythm and strength of the heartbeat can also be noted, as well as whether the blood vessel
feels hard or soft. Changes in your heart rate or rhythm, a weak pulse, or a hard blood
vessel may be caused by heart disease or another problem. As your heart pumps blood
through your body, you can feel a pulsing in some of the blood vessels close to the skin's
surface, such as in your wrist, neck, or upper arm. Counting your pulse rate is a simple way
to find out how fast your heart is beating.
Average Pulse Rates:
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Adult Females: 76 to 80
- Adult Males: about 72
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Newborns: up to 140
- Children: about 90
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Elderly: 50 to 65
How does the heart work with blood and blood vessels to maintain vital functions?
As earlier outlined the heart has 5 main functions which ensure blood is healthy, nourishing,
clean, functions effectively and pumped adequately around the body. The heart works
together with the blood and blood vessels to maintain these 5 functions.
So what are blood vessels?
There are 3 main types of blood vessel:
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Arteries - The walls (outer structure) of arteries contain smooth muscle fibre that
contract and relax under the instructions of the sympathetic nervous system. The
arteries transport blood away from the heart and Transport oxygenated blood only
(except in the case of the pulmonary artery).
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Veins - The walls of veins consist of three layers of tissues that are thinner and less
elastic than the corresponding layers of arteries. Veins include valves that aid the
return of blood to the heart by preventing blood from flowing in the reverse
direction. Veins transport blood towards the heart and transport deoxygenated
blood only (except in the case of the pulmonary vein).
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Capillaries - Capillaries are extremely narrow blood vessels with a diameter of one
cell thick. Capillaries are the smallest of all blood vessels and form the connection
Laura Spenceley
Task 1 - Cardiovascular
Anatomy & Physiology
between veins and arteries. As arteries branch and divide into arterioles and
continue to reduce in size as they reach the muscle they become capillaries. Here the
capillaries form a capillary bed, which is a vast expanse of very small vessels forming
a network throughout the muscle. However, unlike veins and arteries, their main
function is not transporting blood. They are specially designed to allow the
movement of substances, mainly gases oxygen and Carbon Dioxide into and out of
the capillary.
How they work together with heart –
Blood vessels work together with the heart to supply the main 5 functions of the heart with
blood. Task 2 shows how blood is pumped around the body by the heart and blood vessels
in more detail. The hearts contractions pump blood out of the heart via arteries which carry
oxygenated blood around the body to all cells which require a fresh supply of oxygen for
prime function. Arteries divide as they leave the heart and branch into smaller arteries.
Smaller arteries have more smooth muscle tissue to control the changing pressure in blood
flow due to the hearts contractions. Veins carry deoxygenated blood back towards the heart
so blood cells can be replenished with fresh oxygen. This carrying back to the heart for
oxygenation is essential for the functioning of all cells which require oxygen. Capillaries are
essential for the effective movement of substances from red blood cells in capillaries into
muscle cells.
There are 3 main types of blood cell:
Red blood cells (Erythrocytes) –
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Made in the bone marrow of some bones, including ribs, vertebrae and some
limb bones. Produced at a very fast rate.
Transport O2 from lungs to all respiring tissues. Prepare CO2 for transport
from all respiring tissues to lungs.
Contain haemoglobin (Hb), a red iron containing pigment which can carry
O2. In the lungs, Hb combines with O2 to form oxyhaemoglobin. In other
organs, oxyhaemoglobin splits up into Hb and O2.
They have no nucleus so can fit more Hb inside the cytoplasm
They have a special biconcave disc shape therefore increases the surface area
and makes the diffusion of oxygen into & out of the cell easier.
Old red blood cells are broken down in the liver, spleen and bone marrow.
Some of the iron from the Hb is stored, and used for making new Hb, some of
it is turned into bile pigment and excreted.
White blood cells ( Leukocytes) –
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Made in the bone marrow and in the lymph nodes.
They have a nucleus, often large and lobed.
They can move around and squeeze out through the walls of blood capillaries into all
parts of the body.
There are different kinds of white blood cells. They all have the function of fighting
pathogens and to clear up any dead body cells in your body:
Laura Spenceley

Task 1 - Cardiovascular
Anatomy & Physiology
A) Phagocytes –
1. Can move out of capillaries to the site of an infection.
2. Remove any microorganisms that invade the body and might cause
infection, engulf and kill them by digesting them.
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B) Lymphocytes – these blood cells produce antibodies to fight bacteria and foreign
bodies, there are 2 types of Lymphocytes;
1. B-lymphocytes: secrete special proteins called antibodies in response
to contact with their particular antigen, which may be an
invading pathogen or a foreign tissue that has been transplanted.
2. T-lymphocytes: attack foreign or infected cells and kill them.
Platelets –
How they work in blood to maintain function