Human Respiratory System

A system that provides a large surface

area for the diffusion of O2 into the

blood, and the diffusion of CO2 out of

the blood in order to maintain

homeostasis.

Human Respiratory System and

Homeostasis

• Responsible for

– Obtaining oxygen for cells

– Ridding the body of waste (carbon dioxide)

Requirements for Respiration

• 2 requirements

• Humans require a surface for gas exchange

that is big enough for exchange of oxygen

and carbon dioxide at a rate to meet

organisms metabolic rate.

• Take place in a moist environment so that

oxygen and carbon dioxide are dissolved

Parts of the Respiratory System

Two Main Sections of Respiratory System

• Upper Respiratory

– Nasal cavity

– Pharynx

– Epiglottis

– Larynx

– Trachea

• Lower Respiratory

– Bronchii

– Bronchioles

– Alveoli/Lungs

– Diaphragm

Oral and Nasal Cavities

• Structure - openings through which air

enters the system. Nasal cavity is the

chamber behind the nose. It contains hairs,

cilia, and mucus.

• Function - the nose and nasal cavities have

the following functions:

• (A) air is cleansed by the mucus, cilia, and

hair

Oral and Nasal Cavities

• (B) air is heated by blood passing through a large

number of capillaries just below the mucus

membranes. Must be at 37 degrees for optimal

performance

• (C) mucus membranes moisten the air

• The cleansing, heating, and moistening of the air

prevents damage to the delicate lung tissue.

Pharynx

• Structure - cavity behind the nasal cavity

that is common to the respiratory and

digestive systems. It contains two lymph

glands: adenoids and tonsils.

• Function - transports air between the nasal

cavity/mouth and the trachea.

Larynx (Voice Box)

• Structure - consists of several pieces of cartilage.

Located inside is elastic tissue known as vocal

cords.

• Function - When you breathe there is a gap

between cords.

• When you speak gap closes the vocal cords vibrate

as air goes through them producing sound.

• The pitch of the sound produced depends on the

length of the vocal cords. Long length produces

low sound, while shorter cord produces a higher

sound

Trachea• Structure - a tube about 10 to 17 cm long containing rings

of cartilage which prevent the tube from collapsing. At the

top is located the epiglottis. It is lined with mucus

membrane that is ciliated. connects pharynx to the bronchii

• Function - a connecting tube that leads air to and from the

lung by passing through the pharynx to the bronchii.

• *Epiglottis - prevents liquids or solids from entering the

lungs.

• *Mucus membrane - produces mucus that traps foreign

materials that are then swept out of the trachea by the cilia.

This material is carried away by food passing down the

esophagus.

Bronchii

• Structure - tubes which branch from the

trachea leading into the two lungs.

• Function - a connecting tube that leads air

to and from the lung.

Bronchials

• Structure - small tubes that branch from the

bronchi inside the lungs. Lined with ciliated

mucous membrane

• Function - connecting tubes that lead from

the bronchi to the bronchioles.

Bronchioles

• Structure - yet smaller tubes that branch

from the bronchials inside the lung.

• Function - connecting tubes that lead from

the bronchials to the alveoli. Brings air deep

into the lungs

Lungs• Structure:

• Protected by the ribs, sternum, and spine.

• Surrounded by two membranes called pleura.

The pleura isolates the lungs and protects the

delicate tissue. A lubricating fluid is found

between the two layers allowing the lungs to

move freely in the chest cavity during breathing.

• Function - contain a variety of tubes and

chambers where gases are exchanged between the

lungs and the blood.

• Humans have 2 lungs

– Left has 2 lobes and the right has 3 lobes

– Left lung has 2 lobes making it slightly smaller

than right to make room for the heart

• Contains thousands of alveoli that inflate

with air

• Surface of as typical lung can cover a

Tennis court

Lung Systems

• Vary from species to species, but they all

have 3 basic elements:

– One or two lungs that have a moist respiratory

surface

– Means of forcibly bringing air in contact with

lung surface

– Circulatory system to carry gases between

lungs and the other cells of the body

Diaphragm

• Structure - sheet of muscle that separates

the thorax (chest) and abdomen cavities.

• Function - its movement is responsible for

breathing.

• Inspiration (inhale) - diaphragm contracts

• Expiration (exhale) - diaphragm relaxes

Alveoli

• Structure - millions per lung, giving the lungs a

very large surface area for gas exchange. They

are found at the ends of the bronchioles and are a

cluster of microscopic, one cell thick, grape-like

air sacs. They are moist and surrounded by

capillaries.

• Function - site of gas exchange between the air in

the lungs and the blood in the capillaries. Gas

exchange takes place through simple diffusion

but 30%occurs through facilitated diffusion

Alveoli of the Lungs

Steps in Gas exchange in Alveolus

• Oxygen is bought to the surface of an alveolus by

inhaling air

• Oxygen diffuses across the alveolar membrane via

concentration gradient and into a capillary. Water is

needed at the surface between the alveolus and the

capillary to facilitate the diffusion of gases(oxygen and

carbon dioxide).

• At the same time carbon dioxide in the blood diffuses

across the membrane and into the alveolus. This happens

in the opposite direction to oxygen

• The carbon dioxide is then sent back up the airway to be

expelled to the outside

Process of Breathing• Definition - breathing is a mechanical process where

gases are exchanged between the lungs and the

atmosphere. Breathing is the first step in

respiration.

• Breathing occurs due to changes in the pressure in

the thorax or chest cavity of the body. This pressure

is controlled by changing the size of the thorax.

Two structures responsible for changing the size of

the thorax are: ribs and rib muscles (intercostal muscle)

diaphragm

Inhalation (Inspiration)• Definition - air enters the lungs

• Process - there are six steps to the process:

• (1) rib muscle and diaphragm contract

• (2) ribs move up and out

• (3) diaphragm moves down

• (4) thorax increases in size or volume

• (5) pressure decreases in the thorax due to increase in

volume. The result is lower pressure inside the thorax

than outside.

• (6) air rushes into the lungs

• When the above happens it increases the

volume of the chest cavity. This creates a

low pressure inside the chest. The pressure

inside the chest is less than the pressure

outside the body.

• Air rushes into the lungs from the outside

• The lungs inflate

Exhalation (Expiration)• Definition - air leaves the lungs

• Process - there are six steps to the process:

• (1) rib muscle and diaphragm relax

• (2) ribs move down and in

• (3) diaphragm moves up

• (4) thorax decreases in size or volume

• (5) pressure increases in the thorax due to decrease in

volume. The result is a higher pressure inside the

thorax than outside.

• (6) air rushes out of the lungs

• When this happens it decreases the volume

of the chest cavity. This creates a high

pressure inside the chest. The pressure

inside the chest is greater than the pressure

outside the body

• Air is forced out of the lungs

• The lungs deflate

Rate of Breathing• Breathing is an involuntary response controlled

by a section of the brain called the medulla

oblongata.

• This structure sends impulses to the intercostal

muscles of the ribs and diaphragm, causing them

to contract which produces inspiration.

• When this impulse stops, the intercostal muscle

and diaphragm relax producing expiration.

• The amount of CO2 in the blood determines the

rate of breathing.

• Two sensors located in the circulatory

system measure the CO2 content of the

blood:

carotid artery in the neck

aorta leading from the left

ventricle of the heart

CO2 Level Rate of Breathing

High Fast

Low Slow

* Breathing rates vary with age

and activity.

Stages of Respiration

1. Breathing

(previously discussed)

2. External Respiration

• Definition - exchange of gases between the

alveoli of the lungs and the blood.

• Process - occurs by diffusion

• O2 goes into the blood from the alveoli

• CO2 goes into the alveoli from the blood

3. Gas Transport

• Definition - transportation of gas between the lungs and

body cells.

• Process - the gases enter the blood and combine with

the protein hemoglobin found on the red blood cell

(RBC)

• lung ----> body cells : O2 enters the bloodstream and

combines with the hemoglobin forming oxyhemoglobin

• body cells ----> lung : CO2 enters the bloodstream and

combines with the hemoglobin forming

carboxyhemoglobin

* CO2 also combines with water on

the RBC and in the plasma, this

forms carbonic acid.

Gas Exchange

4. Internal Respiration

• Definition - exchange of gases between the

blood and the cells of the body.

• Process - occurs by diffusion

• O2 goes into the body cells from the blood

• CO2 goes into the blood from the body cells

5. Cellular Respiration

• Definition and Process both covered

previously.

Lung Capacity• What's the difference between normal breathing and a deep

breath?

• Normal breathing does not use up the full capacity of your lungs.

– Tidal Volume; the volume of air inhaled and exhaled in a normal

breathing movement. About 500mL

– Inspiratory reserve volume: is the additional volume of air that can be

taken in beyond a regular or tidal inhalation. About 2000mL

– Expiratory reserve volume: is the additional volume that can be forced

out of the lungs beyond a regular or tidal exhalation. About 1500mL

– Vital Capacity is the total volume of gas that can be moved in or out of the

lungs. It can be calculated as tidal volume + inspiratory reserve volume+

expiratory reserve volume = vital capacity. About 4L

– Residual volume: is the amount of gas that remains in the lungs and the

passageways of the respiratory system even after a full exhalation. This

volume never leaves the respiratory system, if it did the lungs would

collapse. About 1500mL

Diseases of the Respiratory System

Bronchitis

• Definition - inflammation of the bronchial passages. Two

forms:

• Acute - severe form which involves an infection of the air

passages.

• Chronic - less severe form which involves an irritation of

the air passages.

• Symptoms - fever, chest pain, severe coughing and often

the secretion of sputum.

• Causes: infection from coughs and colds

– Smoking

• Treatments: Antibiotics

– Stop smoking

Asthma• Caused by the constriction of bronchial passages and

swelling of their mucus linings.

• It is triggered by a hypersensitivity to various agents

within an individual’s environment.

• Can develop at any age

• Affects can be mild or extremely severe

• Leading cause of childhood hospitalization in Canada

• Symptoms – occur in episodes, attack begins with

pressure in the chest, feeling of suffocation, with severe

bouts of uncontrollable coughing and the secretion of a

thick mucous sputum.

What happens during an asthma attack?– Airway swells

– Bronchial muscles tighten

– Increased mucous is secreted in the airway

• Common triggers are:

– colds and chest infections,

– exercise and sports,

– exposure to pollen,

– flowers, grass, plants, trees,

– exposure to tobacco,

– dust,

– cold air,

– pets mould and mildew

How to manage Asthma

– Through lifestyle changes and medications

– Reduce contact with triggers

– Test for allergens

– Keep asthma diary

– Use medications

• Types of meds used:

– anti-inflammatory agents: which help prevent attacks

by delaying or interrupting inflammation, and they

help end attacks

– Bronchodilators: relax bronchial muscles and open up

airways

Causes of pneumonia

• Infection by

– bacteria,

– viruses,

– mycoplasma,

– fungi and

– other infectious agents

– and some chemicals

Types• Bacterial pneumonia

– occurs in lobar pneumonia

– is caused by an invasion of streptococcus pneumonia.

– Can get a vaccination to provide long term

protection

• Viruses

– usually attacks upper respiratory,

– but they also cause many forms of pneumonia.

– Is less serious then other forms and

– last for long periods of time

• Mycoplasma pneumonia: Walking Pneumonia

– caused by small free living agents of disease in humans.

– Have characteristics of both bacteria and viruses.

– Patients require a long recovery period and can be weak

for a long time

• Symptoms - fever, pain in the chest while breathing,

cough, and sshortness of breath, shivering, chills, headache,

delirium (confusion), severe bad breath, muscle pain,

weakness, blue lips and nail beds from lack of oxygen in

the blood

Treatments• The best approach to treating pneumonia depends on a

number of factors, including your age and general health,

the organism or organisms involved, and the setting —

community or health care — where the infection

developed.

• Medication

Antibiotics are used to treat bacterial pneumonia.

• Antivirals

• Fever reducers

• Cough medicine

• Hospital admission

Cancer• Cancer is the uncontrollable

multiplication of cells. Cancer may

occur in any part of the body, and

therefore in any part of the

respiratory system.

Lung Cancer• Uncontrolled and invasive growth of abnormal cells in

lungs and is the leading cancer killer of both men and

women in North America

• Carcinoma

– Malignant tumour

– grows abnormal cells that continue to multiply and

take over healthy cells.

• Death is caused by

– difficulty in breathing,

– or cancer moving out of lungs And into brain or other

body parts

• Causes

– 87% of lung cancer is due to smoking(Carcinogens)

– Another cause is exposure to radon an element used in

radiotherapy(12%)

• symptoms

– Chronic cough,

– coughing up blood,

– weigh loss

– los of appetite,

– shortness of breath

– chest pain

– and fever without cause

• Effects of Lung Cancer

– Death but not by difficulty breathing. Death is

normally caused by the cancer moving out of

lungs an into other body parts such as the brain

• Treatments

– Radiation and chemotherapy if not too far

advanced

Emphysema• A progressive disease in which the tissues of the

lungs lose their elasticity, and therefore the volume

of air that the lungs are able to handle continually

decreases.

• Alveoli are distended and their walls are so damaged

that the surface available for gas exchange is reduced

and less oxygen is available to the brain and tissues

• The deterioration in the lungs is permanent and

irreversible.

• Symptoms - severe coughing, shortness of breath,

and wheezing; developing into difficulty in

breathing. It sometimes results in disability and

death.

• Treatments:

– reduce or eliminate smoking

– exercise,

– some drugs help to keep alveoli working

– and supplemental oxygen

Influenza

• A viral infection of the respiratory tract,

especially the trachea. Commonly called flu.

Reduces a person’s resistance making them

susceptible to further infections such as

pneumonia.

• Symptoms - sore throat, nasal discharge, fever,

chills, headache, aching of muscles and joints,

upset stomach

• Treatments:

– Treat symptoms — .

– Rest until the flu is fully resolved, especially if the

illness has been severe

– Fluids — Drink enough fluids so that you do not

become dehydrated.

– Acetaminophen (such as Tylenol® and other brands)

can relieve fever, headache, and muscle aches.

– Cough medicines are not usually helpful; cough usually

resolves without treatment.

Common Cold

• A viral infection of the upper respiratory

tract.

• Symptoms - sneezing, headaches, sore

throat, nasal discharge

Pleurisy

• Inflammation of the pleura membranes that

surrounds the lungs. Most cases are due to

infections, and many are associated with

pneumonia.

• Symptoms - sharp pain brought on by

breathing and coughing. Patient breaths

shallowly.

Treatments• Use an anti-inflammatory medicine, such as

ibuprofen (Motrin) or aspirin, to reduce the pain

and inflammation.

• You may have less pain if you lie on the side that

hurts.

• Avoid exerting yourself or doing anything that

would cause you to breathe hard.

• Call your doctor or go to your hospital's emergency

department if you can't breathe deeply or cough

because of severe pain

Carbon Monoxide Poisoning• Definition - Carbon monoxide is a chemical

compound consisting of one atom of carbon

and one atom of oxygen (CO). It is an

odorless and tasteless gas.

• Source - It is produced when organic

compounds are burned with an insufficient

air supply.

• Effects - When inhaled, it combines with

the hemoglobin on the RBC, preventing

absorption of oxygen.

• Symptoms - symptoms are normally mild

and include nausea, headache, or fatigue.

Excessive inhalation can be more serious,

even fatal.

• Treatment - remove the individual from the

source of CO. Perform mouth to mouth

resuscitation if necessary.

Emphysema• The swelling and scarring of alveoli in the lung resulting in

loss of elasticity( cannot inflate and deflate) of the alveoli.

This causes some of them to burst resulting in decrease of

surface area for gas exchange

• Difficulty in breathing

• Causes of emphysema

– Smoking

– Other agents

• Treatments for emphysema

– Stop smoking

– Drugs to make alveoli work

– Extra oxygen