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Respiratory system - Biology SL Topic 6.4 mechanism of ventilation, inspiration, gas exchange, alveoli,

Biology SL Topic 6.4 mechanism of ventilation, inspiration, gas exchan...
Subject

Biology SL

707 Documents
Students shared 707 documents in this course
Level

IB

Academic year: 2017/2018
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Overview of respiratory ➢ Aerobic cell respirationis a biochemical pathway in which the chemical bonds within a glucose molecule are broken down sequentially to release energy ○ This energy is stored as ATP ➢ Oxygen in the alveoli diuses into the bloodstream and carbon dioxide from the bloodstream diuses into the alveoli ○ Alveoliis a multitude of small spherical air sacs

The mechanism of ventilation ➢ The tissue that makes up the lungs is passive and not muscular ➢ There are muscles surrounding the lungs including the diaphragm, muscles of the abdomen and the external and internal intercostal muscles ➢ The mechanism of breathing is based on the inverse relationship between pressure and volume ➢ Lungs are located within thethoracic cavity(orthorax) ○ Thorax is closed to the outside air ➢ There are two environments that aect each other ○ The closed environment of the thorax ○ The internal environment of the lungs

Inspiration ➢ Steps ○ The diaphragm contracts and the external intercostal muscles and one set of abdominal muscles help to raise the rib cage ■ Increase of the volume of the thoracic cavity ○ Because the thoracic cavity has increased its volume, the pressure inside the cavity decreases ■ Less pressure pushes on the lungs ○ The lungs increase their volume ■ The pressure inside the lungs decreases ● Partial vacuum ○ Air comes in through your open mouth or nasal passages to counter the partial vacuum and fill the alveoli ➢ The steps are reverse for an expiration ○ Muscles in the abdomen and internal intercostal muscles in the ribs contract to push air out of the lungs

➢ The abdominal and intercostal muscles can achieve a greater initial thoracic volume leading to deeper breathing ➢ Muscles only perform work when contracting, thus dierent muscles are needed to breathe in and out ○ Each muscle pair is said to have anantagonisticmuscle action ➢ Theintercostal musclesare the muscles that are found between the ribs ○ There are two antagonistic sets of these muscles ■ External intercostal muscles, which are used when breathing in ■ Internal intercostal muscles, which are used when breathing out

Gas exchange ➢ Air enters through the mouth or nasal passages ○ Passes the pharynx ○ Passes the larynx (production of sound) ○ Goes down through the trachea ○ Goes to the right and left primary bronchi ○ Then to smaller and smaller branches of the bronchi ■ The smallest are called bronchioles ○ Reaches the small air sacs in the lungs called alveoli ➢ Alveoli are found in the lungs as clusters at the ends of the smallest bronchioles ○ Approximately 300 million alveoli in each lung ○ Each cluster of alveoli has one or more surroundingcapillary bed(s) ➢ The blood entering these capillary beds comes from the right ventricle via the pulmonary arteries ➢ While the blood is in the capillary bed, oxygen diuses from the air in each alveolus cell through the 2 cells thich membrane ○ One is the single cell making up the alveolus ○ One is the single cell making up the wall of the capillary ➢ Carbon dioxide diuses in the opposite direction through the same 2 cells ○ The gas exchange is ensured by dierent concentration gradients

Alveoli ➢ Alveoli are composed of specialized cells calledpneumocytes ○ 2 types of cells ○ The single layer of cells facilitates oxygen and carbon dioxide diusion ➢ Type I pneumocytes

○ Examples of carcinogens ■ Tobacco ■ Asbestos

If you stop smoking... ➢ After 20 minutes, your blood pressure and pulse areback to normal ➢ After 8 hours, the carbon dioxide levels in the blood decrease and you feel less tired ➢ After 24 hours, the risk of a heart attack decreases ➢ After 2-12 weeks, the circulation is enhanced whichmakes you feel more alert. The skin returns to its natural colour ➢ After 4-6 months, you cough less because the cilia is trachea has recovered ➢ After 1 year, your immune system works as normal and you can resist diseases easier ➢ After 5 years, the risk for cancer has been halved

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Respiratory system - Biology SL Topic 6.4 mechanism of ventilation, inspiration, gas exchange, alveoli,

Subject: Biology SL

707 Documents
Students shared 707 documents in this course
Level:

IB

Was this document helpful?
Gas exchanges Topic 6.4 Biology SL
Overview of respiratory
➢Aerobic cell respiration
is a biochemical pathway in which the chemical bonds
within a glucose molecule are broken down sequentially to release energy
○This energy is stored as ATP
➢Oxygen in the alveoli diuses into the bloodstream and carbon dioxide from the
bloodstream diuses into the alveoli
○
Alveoli
is a multitude of small spherical air sacs
The mechanism of ventilation
➢The tissue that makes up the lungs is passive and not muscular
➢There are muscles surrounding the lungs including the diaphragm, muscles of the
abdomen and the external and internal intercostal muscles
➢The mechanism of breathing is based on the inverse relationship between pressure
and volume
➢Lungs are located within the
thoracic cavity
(or
thorax
)
○Thorax is closed to the outside air
➢There are two environments that aect each other
○The closed environment of the thorax
○The internal environment of the lungs
Inspiration
➢Steps
○The diaphragm contracts and the external intercostal muscles and one set of
abdominal muscles help to raise the rib cage
■Increase of the volume of the thoracic cavity
○Because the thoracic cavity has increased its volume, the pressure inside the
cavity decreases
■Less pressure pushes on the lungs
○The lungs increase their volume
■The pressure inside the lungs decreases
●
Partial vacuum
○Air comes in through your open mouth or nasal passages to counter the
partial vacuum and fill the alveoli
➢The steps are reverse for an expiration
○Muscles in the abdomen and internal intercostal muscles in the ribs
contract to push air out of the lungs
1

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