RESPIRATION:-
“The
term respiration means the exchange of gases between body cells & the
environment. this involves two main process:
1. Breathing [Pulmonary
ventilation]
This is movement of air into and out of the
lungs.
2. Exchange of Gases:-
It takes place
·
In the lungs- external respiration.
·
In the Tissues- Internal respiration.
Breathing:-
Breathing
supplies O2 to the alveoli & Eliminates Co2.
MUSCLES OF BREATHING:-
Expansion
of the chest during inspiration occurs as a result of muscular activity, partly
voluntary & partly involuntary.
The Main Muscles of Breathing are:
1. Intercostal
Muscles
2. Diaphragm.
INTERCOSTAL MUSCLES:-
1. There
are 11 pairs of intercostals muscles that occupy the space between the 12 pairs
of ribs.
2. They
are arranged in two layers, the external & Internal muscles.
The External intercostals muscle Fibres:-
These
exted downwards & forwards from the lower border of the rib above to the
upper border of the rib below.
The Internal intercostals muscle fibres:-
1. These
extend downwards & forwards from the lower border of the rib below,
crossing the external intercostals muscle fibers at rt angels.
2. The
first rib is fixed, therefore, when the intercostals muscle contract they pull
all the other ribs downwards the first rib.
3. The
shape & sizes of the ribs they move outwards when pulled upwards, enlarging
the thoracic cavity.
4. The
intercostals muscles are stimulated to contract by the intercostals nerves.
DIAPHRAGM
DIAPHRAGM
1.
The diaphragm is a dome-shaped muscular structure separating
the thoracic & abdominal cavities.
2.
It forms the floor of the thoracic cavity
& the roof of the abdominal cavity & consists of a central tendor from
which muscle fibres radiate to be attached to the lower ribs & sternum
& to the vertebral column by two crura.
3.
When the muscle of the diaphragm is relaxed
the central tendor is at the level of 8th theoracic Vertebra.”
4.
When it contract its muscle fibres shorten
& the central tender is pulled downwords to the level of the 9th thoracic Vertebra, enlarging the thoracic
cavity in length.
5.
This decreases pressure in the thoracicavity
& increases it in the abnormal & pelvic cavities.
6.
The diphragm is supplies by the “Phrenic nerves”
7.
The intercostals muscles & the diaphragm contract
simmulatenously enlarging the thoracic cavity in tall direction that it from
back to front, side to side & top to top.
CYCLE OF BREATHING
The average respiratory rate is 12 to 15
breaths per minute
Each breath consists of there phases.
1.
Inspiration
2.
Expiration
3.
Pause.
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