767207
Description
Mind Map by leonie1997, updated more than 1 year ago
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Created by leonie1997
almost 11 years ago
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Human health and physiology -
The cardiovascular system
- Heart stucture
- The heart is a double pump, with the right side
pumping blood to the lungs and the left side
pumping blood to all other organs.
- The walls of the heart are
composed of cardiac muscle.
- Contraction of cardiac muscle is
myogenic - it can contract on its own,
without being stimulated by a nerve.
- Contraction of cardiac muscle is
myogenic - it can contract on its own,
without being stimulated by a nerve.
- There are many capillaries in the
muscular wall of the heart.
- The blood running through these capillaries is
supplied by the coronary arteries, which branch
of the aorta, close to the semilunar valve.
- The blood brought by the coronary arteries brings nutrients.
It also brings oxygen for aerobic cell respiration, which
provides the energy needed for cardiac muscle contraction.
- The blood brought by the coronary arteries brings nutrients.
It also brings oxygen for aerobic cell respiration, which
provides the energy needed for cardiac muscle contraction.
- The blood running through these capillaries is
supplied by the coronary arteries, which branch
of the aorta, close to the semilunar valve.
- The heart is a double pump, with the right side
pumping blood to the lungs and the left side
pumping blood to all other organs.
- The action of the heart
- The atria are collecting
chambers - they collect blood
from the veins.
- The ventricles are pumping
chambers - they pump blood out
into the arteries at high pressure.
- The valves ensure that the
blood always flows in the
correct direction.
- Every heart beat consists of
a sequence of actions:
- 1. The walls of the atria contract, pushing
blood from the atria into the ventricles
though the atrioventricular valves, which
are open. The semilunar valves are
closed, so the ventricles fill with blood.
- 2. The walls of the ventricles contract powerfully
and the blood pressure rapidly rises inside them.
This rise in pressure causes the atrioventricular
valves to close, preventing back-flow of blood into
the atria and then causes the semilunar valves to
open, allowing blood to be pumped into the
arteries. At the same time the atria start to refill
as they collect blood from the veins.
- 3. The ventricles stop contracting as pressure
falls inside them the semilunar valves close,
preventing back-flow of blood from the
arteries to the ventricles. When the ventricular
pressure drops below the atrial pressure, the
atrioventricular valves open. Blood entering
the atrium from the veins then flows on to start
filling the ventricles.
- 4. The next heart beat begins when the
walls of the atria contract again.
- 1. The walls of the atria contract, pushing
blood from the atria into the ventricles
though the atrioventricular valves, which
are open. The semilunar valves are
closed, so the ventricles fill with blood.
- The atria are collecting
chambers - they collect blood
from the veins.
- The control of the heart beat
- Heart muscle tissue has a special
property - it can contract on its own
without being stimulated by a nerve.
- One region is responsible for initiating each
contraction. This region is called the pacemaker and is
located in the wall of the right atrium.
- Each time the pacemaker sends out a signal the
heart carries out a contraction or beat.
- Nerves are hormones can transmit
messages to the pacemaker.
- One nerve carries massages from the brain to
the pacemaker that tells the pacemaker to
speed up the beating of the heart.
- Another nerve carries messages from the brain to
the pacemaker that tell the pacemaker to slow
down the beating.
- Adrenalin, carried to the pacemaker by
the blood stream, tells the pacemaker to
speed up the beating of the heart.
- One nerve carries massages from the brain to
the pacemaker that tells the pacemaker to
speed up the beating of the heart.
- Heart muscle tissue has a special
property - it can contract on its own
without being stimulated by a nerve.
- Blood vessels
- Arteries
- Thick outer layer of longitudinal
collagen and elastic fibres to
avoid bulges and leaks.
- Thick wall to withstand
the high pressures.
- Thick layers of circular elastic and
muscle fibres to help pump the
blood on after each heart beat.
- Narrow lumen to help maintain the
high pressures.
- Thick outer layer of longitudinal
collagen and elastic fibres to
avoid bulges and leaks.
- Veins
- Thin layers with a few circular elastic and muscle
fibres because blood does not flow in pulses so the
veins wall cannot help pump it.
- Wide lumen is needed to
accomodate the slow-flowing blood.
- Thin wall allows the vein to be pressed
flat by adjacent muscles, helping to move
the blood.
- Thin outer layer of longitudinal collagen
and elastic fibres because there is little
danger of bursting.
- Thin layers with a few circular elastic and muscle
fibres because blood does not flow in pulses so the
veins wall cannot help pump it.
- Capillaries
- Wall consists of a single layer of
thin cells so the distance for
diffusion in or out is small.
- Pores between cells int he wall allow some
of the plasma to leak out and form tissue
fluid. Phagocytes can also squeeze out.
- Very narrow lumen - only about 10um across
so that capillaries fit into small spaces. Many
small capillaries have a larger surface area than
fewer wide ones.
- Wall consists of a single layer of
thin cells so the distance for
diffusion in or out is small.
- Arteries
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