respiratory system, respiratory mechanism and volumes and capacities, Human Respiratory system, gaseous exchange, pulmonary system, submitted by Garima Mittal

1. Human
Respiratory
System
Submitted by:
Garima Mittal
Asst. Professor,
Dept. of Pharmacy,
PIET, Panipat

2. The respiratory system has many different parts that work together to help you
breathe. Your airways deliver air to your lungs. Your airways are a complicated
system that includes your:
Mouth and nose: Openings that pull air from outside your body into your
respiratory system.
Sinuses: Hollow areas between the bones in your head that help regulate the
temperature and humidity of the air you inhale.
Pharynx (throat): Tube that delivers air from your mouth and nose to the
trachea (windpipe).
Trachea: Passage connecting your throat and lungs.
Bronchial tubes: Tubes at the bottom of your windpipe that connect into each
lung.
Lungs: Two organs that remove oxygen from the air and pass it into your blood.
From your lungs, your bloodstream delivers oxygen to all your organs and other
tissues.

4. From your lungs, your bloodstream delivers oxygen to all your organs and other
tissues. Muscles and bones help move the air you inhale into and out of your lungs.
Some of the bones and muscles in the respiratory system include your:
Diaphragm: Muscle that helps your lungs pull in air and push it out.
Ribs: Bones that surround and protect your lungs and heart.
When you breathe out, your blood carries carbon dioxide and other waste out of the
body.
Other components that work with the lungs and blood vessels include:
Alveoli: Tiny air sacs in the lungs where the exchange of oxygen and carbon
dioxide takes place.
Bronchioles: Small branches of the bronchial tubes that lead to the alveoli.
Capillaries: Blood vessels in the alveoli walls that move oxygen and carbon
dioxide.
Lung lobes: Sections of the lungs — three lobes in the right lung and two in the

5. Some of the other components of your respiratory system include:
Cilia: Tiny hairs that move in a wave-like motion to filter dust and other irritants
out of your airways.
Epiglottis: Tissue flap at the entrance to the trachea that closes when you
swallow to keep food and liquids out of your airway.
Larynx (voice box): Hollow organ that allows you to talk and make sounds
when air moves in and out.

6. The respiratory system has many functions. Besides helping you inhale
(breathe in) and exhale (breathe out), it:
Allows you to smell.
Warms air to match your body temperature and moisturizes it to the
humidity level your body needs.
It also helps in regulation of Blood pH.
It filters inspired air, involved in production of vocal sounds (Phonation)
Delivers oxygen to the cells in your body.
Removes waste gases, including carbon dioxide, water and heat, from the
body when you exhale.
Protects your airways from harmful substances and irritants

7. The action of breathing in and out is due to changes of pressure within the thorax, in
comparison with outside.
Atmospheric pressure is = 760mmHg
Pressure is necessary for breathing, which is why it is difficult in high altitude and
also why a punctured lung can be dangerous.

8. During gas exchange oxygen moves from the lungs to the bloodstream. At
the same time carbon dioxide passes from the blood to the lungs. This happens
in the lungs between the alveoli and a network of tiny blood vessels called
capillaries, which are located in the walls of the alveoli.

10. Changes in respiratory system brought by breathing in and
out.

11. Respiratory center is widely dispersed in
group of neurons, located bilaterally in the
medulla oblongata and pons of the brain
stem.
It is divided into three areas:
1. The Medullary Rhythmicity area in the
Medulla Oblongata which control the
basic rhythmicity of the respiration.
2. The Pneumotaxic Area in the upper
Pons which co-ordinates the transition
between inhalation and exhalation. It
works by sending inhibitory impulses to
the inspiratory center, terminating
inspiration, and thereby regulating
inspiratory volume and respiratory rate.
This center likely is involved in the fine-
tuning of breathing.
3. The Apneustic Area also in the pons
which co-ordinates the transition between
inhalation and exhalation.
Respiratory centers/
Respiratory centers located in brain can regulate the process of respiration.

12. Lung volumes are also known as Respiratory/Pulmonary volumes.
It refers to the volume of gas in the lungs at a given time during the respiratory
cycle.
Lung capacities are derived from a summation of different lung volumes. A breath is
one complete respiratory cycle that consists of one inspiration and one expiration.
Under normal conditions, the average adult takes about 12 - 15 breaths per minute.
The average total lung capacity of an adult human male is about 6 litres/min.
An instrument known as a SPIROMETER/RESPIROMETER,
which is used to measure the volume of air (SPIROGRAM)
that moves into and out of the lungs, and the process of
taking the measurements is called SPIROMETERY.
Respiratory (pulmonary) volumes are an important aspect of pulmonary function
testing because they can provide information about the physical condition of the
lungs.
Minute Ventilation (MV)/Total Lung capacity = 12 breaths/min. x 500ml/breath= 6
lit./min.

13. There are 4 Basic Respiratory Volumes with the virtue of which we can
calculate the other volumes/ capacities:
1. Tidal volume (TV): The amount of air breathed in or out during one normal breath.
It is about 500 ml.
2. Inspiratory Reserve Volume (IRV): The additional amount of air that can be
inhaled after a normal deep breath/inhalation. It is about 3100 ml (Male) and 1900
ml (Female) in adults.
3. Expiratory reserve volume (ERV): The additional amount of air that can be
exhaled after a deep/forceful exhalation. It is the reserve amount that can be
exhaled beyond what is normal and it is about 1200 ml (Male) and 700 ml
(Female) in healthy adults.
4. Residual Volume (RV): The amount of air that is left after expiratory reserve
volume is exhaled. The lungs are never completely empty; there is always some
air left in the lungs after a maximal exhalation. If this residual volume did not exist
and the lungs emptied completely, the lung tissues would stick together. This
volume cannot be measured, only calculated which is about 1200 ml (male) and
1100 ml (Female) in healthy adults.

15. Other Volumes that are not measured but calculated are:
5. Vital Capacity (VC=ERV+TV+IRV): Measures the maximum amount of air that
can be inhaled or exhaled during a respiratory cycle. It is the sum of Expiratory
Reserve Volume (ERV), Tidal Volume (TV) , and Inspiratory Reserve Volume (IRV).
It is about 4800 ml (Male) and 3100ml (female).
6. Inspiratory Capacity (IC=TV+IRV): Measures the amount of air that can be
inhaled after the end of a normal expiration. It is, therefore, the sum of the Tidal
Volume and Inspiratory Reserve Volume i.e. 3600 ml (Male) and 2400 ml (female).
7. Functional Residual Capacity (FRC=ERV+RV): The FRC measures the
amount of additional air that can be exhaled after a normal exhalation. it is the sum
of Residual Volume and Expiratory Reserve Volume which is about 2400 ml (Male)
and 1800ml (female).
8. Total lung Capacity (TLC=RV+ERV+TV+IRV): It is a measurement of the total
amount of air that the lung can hold. It is the sum of the Residual Volume (RV),
Expiratory Reserve Volume (ERV), Tidal Volume (TV) , and Inspiratory Reserve
Volume (IRV). It is about 6000ml (male) and 4200ml (female)