Unit 5: Anatomy and Physiology - The role of energy in the body P4 M1 D1
P4 - Explain in the physiology of two names body systems in relations to energy metabolism
M1 - Discuss the role of energy in the body
1 – Analyse how two body systems interrelate to perform a named functions
It is important to understand the functions of the body systems and their
association with energy metabolism. This booklet will provide information on
how the body requires and utilises energy.
P4 - Explain in the physiology of two names body systems in relations to
energy metabolism
1. Cardiovascular system
The cardiovascular system
has both sides of the heart
working together and a
heartbeat with one
complete contraction and
relaxation. After
contraction the
compartment has been
emptied of blood it, relaxes
to be filled with blood once
more. Alongside the
ventricles, which is a
chamber filled with fluid
that contain more muscle
than the atria which are
two chambers and
generate more pressure to
force the blood in a greater
distance. There are
differences in the
thickness of the walls of the chambers. As the muscles of each chamber
contracts to create an increase pressure in the blood and the higher the
pressure created in the heart, the further it will push the blood.
o Atria - the muscle of the atria is very thin, as these chambers do not
need to create much pressure, as their function is to push the blood to
the ventricles.
o Right ventricle - its walls being thicker than the walls of the atria as the
right ventricle job is to pump blood out of the heart. But the walls of the
right ventricle are much thinner than the left ventricle
o Left ventricle - has a thicker muscular wall, as it can be two or three
times thicker than those of the right ventricle. The blood from the left
ventricle is pumped out through the aorta (the largest artery in the
body) and needs sufficient pressure to overcome the resistance of the
systemic circulation.
The cardiac cycle
The cardiac cycle is the period of time that begins with contraction of the atria
and ends with ventricular relaxation. Systole is involved which is the period of
contraction that the heart undergoes whilst it pumps up blood into circulation.
As well as diastole – the period of relaxation that occurs as the chambers is
filled with blood. Both the atria and ventricles undergo systole and diastole
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,Unit 5: Anatomy and Physiology
and are important for these components to be carefully regulated and
coordinated to ensure blood is being pumped efficiently to the body. At the
beginning of the cardiac cycle, both the atria and ventricles are
diastole/relaxed. With blood
flowing into the right atrium from
the superior and inferior venae
cavae and the coronary sinus
and the blood flows into the left
atrium from the four pulmonary
veins. Of the two atrioventricular
valves, the tricuspid and mitral
valves that are both open, letting
blood flow unconstrained from
the atria and into the ventricles.
As well as the two semilunar
valves, the pulmonary and aortic
valves are closed to prevent
backflow of blood into the right
and left ventricles from the
pulmonary trunk on the right and
aorta on the left. Lumen
Learning. Anatomy & Physiology. [Online] [Accessed on 18th March 2018]
https://courses.lumenlearning.com/suny-ap2/chapter/cardiac-cycle/
1. Contraction of the atria (atrial systole and diastole)
This stage involves the contraction of the atrial muscle as the volume of atria
decreases whilst the pressure on blood increases. This causes blood to be
forced down into ventricles and the atrioventricular valves pushed open.
2. Contraction of the ventricles (ventricular systole)
This stage involves the ventricle muscle to contract bottom up with the volume
of ventricle decreases and the blood pressure increases. The blood then
forces upwards as the atrioventricular valves are pushed to shut whilst the
semi-lunar valves are pushed open to let blood enter the arteries. Blood
entering the atria through the veins also have higher pressure there.
3. Relaxation of the heart (diastole)
This stage has the cardiac muscles relaxes with the semi-lunar valves closing
as the higher pressure in arteries occurs. The volumes of atria and ventricles
increase as the pressure inside the heart decreases. Blood at a higher
pressure outside the heart and enters the atria through the veins. With some
blood trickling through the atrioventricular valves into the ventricles.
Valves
Valves like the semi-lunar valves and atrioventricular valves, etc., prevent the
backflow of blood. As a valve will open when there is higher pressure behind
the valve than in front of it. An example of this is when there is higher
pressure in the atrium where the blood has come from compared with the
ventricle where the blood passes into then the atrioventricular valve that is
between the atrium and ventricle will close.
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, Unit 5: Anatomy and Physiology
o What makes the heart sound is the familiar lub-dup sound made by the
heart from the valves closing. As the atrioventricular valves closing as
make the first sound of the lub the ventricles begin to contract. Whilst the
second sound of the dup is made by the semilunar valves closing as the
ventricles start to relax. As the atrioventricular valves snap shut which
makes a louder noise than the closing of the semilunar valves, which shut
because blood is accumulating in their pockets.
o And the myogenic (cardiac muscle) stimulation of the heart where its
contraction is initiated from within the
muscle itself rather than the nervous
impulses from the neurogenic which is
from the outside as is the case with
other muscles. And a region of the
brain of the medulla oblongata controls
the autonomic nervous system
controls the heart rate with changes to
the heart rate. This has two centres
that the autonomic nervous system
controls the heart rate of:
1. A centre that increases heart rate that links to the heart’s sinoatrial
node by the sympathetic nervous system.
2. A centre that decreases in heart rate as it is linked to the heart’s
sinoatrial node by the parasympathetic nervous system.
o Cardiac output is the volume of blood that is pumped by one ventricle of
the heart in one minute and is measured in dm 3min-1 and it dependent on
two factors including the:
The heart rate which is the rate the heart beats
The stroke volume which is the volume of blood pumped out at each
beat
The cardiac output is calculated as
Cardiac output = Heart rate x Stroke volumes
dm3min-1 min-1 dm3
Blood Vessels
There are 3 types of blood vessels
within the cardiovascular system,
which all have different properties
and appearances:
Arteries
The arteries carry out blood away
from the heart as when pressure is
high and when it is cut it spurts
out. Whilst the artery walls are
thick, muscular and very elastic
with the blood they carry is bright
with oxygen content. The arteries
can also stretch as blood is pumped in and the muscle wall contracts to force
blood along.
Veins
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