The Respiratory System

Overview

• Oxygen is important to our body.

• The cardiovascular and respiratory system share responsibility for supplying the body with oxygen and disposing of carbon dioxide.

Functional Anatomy of The Respiratory System

• The are two catagories of respiratory system – conducting zone structures :

• Purify, humidify, and warm incoming air • nose, pharynx, larynx, trachea, primary bronchi

– the respiratory zone : • gas exchanges • bronchioles, alveolar duct, alveolar sacs, and

alveoli

The Nose • Only externally visible part of the respiratory • The olfactory receptor are located in the mucosa in superior part of

nasal cavity, just beneath the ethmoid bone • The mucosa's glands produce sticky mucus and moistens the air

and traps incoming bacteria and other foreign debris • In cold temperature, cilia become sluggish, mucus accumalate in

the nasal cavity and dribble outward. • Is surounded by a ring of paranasal that function to

– Act as resonant chamber for speech – Produce mucus which drains into the nasal cavities – The suctioning effect created by nose blowing help to drain the

sinuses – The nasolacrimal duct which drain tears from the eyes also

empty into nasal

Homeostatic Imbalance

• The genetic defect cleft palate

• Rhinitis

• Sinusitis

Pharynx (throat) • The length is about 13 cm (5 inches).

• It is a common passageway for food and air.

• The auditory tube that drain the middle ear, open nasopharynx.

• The are 3 portion of pharynx

– Nasopharynx (area at top of throat behind nose)

– Oropharynx ( area at middle of throat behind mouth)

– Laryngopharynx ( area at lower part of the throat)

• Tonsil ( cluster of lymphatic tissue)

– Pharyngeal tonsil (high in the nasopharynx)

– Palatine tonsil (at the end of the soft palate)

– Lingual tonsil (at the base of tongue)

Homeostatic imbalance

• Pharyngitis

• Tonsillitis

Larynx (voice box)

• Plays a role in speech.

• Located inferior to the pharynx.

• Formed by 8 rigid hyaline cartilage such as thyroid cartilage or adam's apple.

• And a spoon-shaped flap of elastic cartilage such as epiglotis

• Homeostatic = cough reflex

Trachea

• The length is about 10-12 cm (4 inches) or from larynx to the fifth thoracic.

• C-shaped rings of hyline cartilage

• Approximately midchest

• Is lined with a ciliated mucosa

• The work of cilia is the opposite of incoming air.

Homeostatic imbalance

• Cigarette smoking

– Inhibits ciliary activity and destroy

– Coughing ( to change the function of cilia)

Primary Bronchi

• The right and left primary bronchi are formed by the division of the trachea.

• The right primary bronchus is wider, shorter, and straighter then left.

• The smaller subdivisions of bronchi are bronchioles that are route to the air sacs.

Lungs

• The paired lungs are fairly organs that occupy the entire thoracic cavity except the mediastinum

• 'Apex' is narrow superior portion of each lung, located just deep clavicle.

• 'Base' is the broad lung area resting on diapragm • 'Fissures' is lobe that devide each lung • Left lung has two lobes • Right lung has three lobes • The terminal of bronchioles is alveoli (air sac) • The surface of each lung is covered with visceral pleura called

pulmunary or visceral pleura • The wall of thoracic cavity are lined by parietal pleura. • The respiratory zone : bronchioles, alveolar duct, alveolar sacs,

and alveoli

• There are millions of the clustered alveoli which resemble bunches of grapes, and they make up the bulk of the lungs.

• The lungs are mostly air spaces.

• The balance of the lung tissue, its stroma is elastic connnective tissue

• The lungs weigh only about 2 1/2 pounds

• The lungs are soft and spongy.

Homeostatic imbalance

• Pleurisy (inflammation of the pleura). Pleura becomes dry and rough.

The Respiratory Membrane

• The walls of the alveoli are composed largely of a single, thin layer of squamous epithelial cells.

• The external surface of the alveoli are covered with a "cobweb" of pulmonary capillaries.

• They together form air-blood barrier

• The gas exchanges occur by simple diffusion through the respiratory membrane

• The final line of defense for the respiratory system are the macrophages

• Surfactant to coats the gas-exposed alveolar surfaces

Respiratory Physiology

At least four distinct events, collectively called respiration must

occur : • Pulmonary ventillation

• External respiration

• Respiratory gas transport

• Internal respiration

Mechanism of Breathing

• The rule to keep in mind about mechanism of breathing:

• "Volume changes lead to pressure changes, which lead to the flow of gases equalize the pressure".

• A gas,like liquid, always conforms to the shape of its container. But unlike liquid, gas fills its container

• Large volume = low pressure

• Narrow/small volume = high pressure

volume

increase =

pressure

decrease

(partial vacum)

volume

decrease =

pressure

increase

asthma, bronchitis and pneumonia become

active process

Homeostatic Imbalance

• The normal intrapleural pressure = Negative

• Atelectasis (lungs collapse). the lung is useless for ventilation

• Pneumothorax is reversed by drawing air out of the intrapleural space with chest tube, which allows the lungs to reinflate and resume its normal function.

Respiratory volume and capacities • Tidal volume (TV) is the amount of air which is into and out of the

lungs with each breath. 500 ml

• Inspiratory reserve volume (IRV) is the amount of air that can be taken in forcibly over the tidal volume. 2100 - 3200 ml

• Expiratory reserve volume (ERV) is the amount of air that can be exhaled after a tidal expiration. 1200 ml

• Resudial volume (RV) is the amount of air that still remains in the lungs after expiration. 1200 ml

• Vital capity (VC) is the sum of the TV+IRV+ERV. About 4800 ml

• Dead space volume is the amount of air that enters respiratory trace remains in the conducting zona passageway. 150 ml

Respiratory sound

• Bronchial sound are produced by air rushing through the large respiratory passageway (trachea and bronchi)

• Vesicular breathing sound occur as air fills the alveoli. It’s soft and resemble a muffled breeze.

External Respiration, Gas Transport, And Internal Respiration

Homeostatic Imbalance

• Hypoxia

– anemia, pulmonary disease, blocked blood circulation, and CO poisoning

control of respiration

• the medulla and pons are the neural centers that control respiratory rhythm and depth

• the activity of respiratory muscles, the diaphragm and external intercostal, is regulated by nerve impulses transmitted to them from the brain by the phrenic ans intercostal nerves.

• in addition, the bronchioles and alveoli have stretch receptor that respond to extreme overinflation (which might damage the lungs)

• the normal of respiratory rate (eupnea) is about 12-15 or 12 - 20 x/mnt.

Intercostal

nerves

Phrenic

nerves

factor influencing respiratory rate and depth

• physical factor – exercise, high body temperature

• volition (conscious control)

• emotional factors

• chemical factor – the level of CO2 and O2

Respiratory Disorders

choronic obstructive pulmonary disease (COPD)

• Chronic bronchitis

– Irritation and inflammation, the mucos produces excessive.

• Emphysema

– The alveoli enlarge as the walls of adjacent chambers break through, as the lung becomes less elastic, the air ways collapse during expiration.

• Lung cancer

– If COPD is not cured, it will cause lung cancer.

The cause of COPD and lung cancer

• These diseases have certain features in common

– Patient almost always have a history of smoking

– Dyspnea often reffered to as "air hunger" occurs and becomes more severe

– Coughing and frequent pulmonary infections are common

– Most COPD victim are hypoxic, retain CO2 and have respiratory acidosis

– Over 90 % of lung cancer patients were smoker