Respiratory System

I. RespirationA. Process filters incoming air and

transports it into the microscopic alveoli where gases are exchanged.

B. Consists of the following:1.Ventilation2.Gas exchange between

blood and lungs3.Gas transport in the

bloodstream4.Gas exchange between the

blood and body cells5.Cellular respiration

II. Organs of the Respiratory System

A. Divided into two groups:1.Upper respiratory tract

a)Noseb)Nasal cavityc)Sinusesd)Pharynx

2.Lower respiratory tracta)Larynxb)Tracheac)Bronchial treed)Lungs

III. Upper Respiratory TractA. Nose- Filters air with coarse

hairs inside the nostrils.B. Nasal Cavity

1. Divided medially by the nasal septum.

2. Nasal Conchaea) Divide the cavity into

passageways (increase surface area)

b) Lined with mucous membrane to warm and filter incoming air.

III. Upper Respiratory TractC. Paranasal Sinuses

1. Air-filled spaces within the maxillary, frontal, ethmoid, and sphenoid bones of the skull.

2. Open to the nasal cavity3. Lined with mucus

membrane4. Continuous with lining of

the nasal cavity.5. Reduce the weight of the

skull6. Serve as a resonant

chamber to affect the quality of the voice.

D. Pharynx- Aids in producing sounds for speech.

IV. Lower Respiratory TractA. Larynx

1. Enlargement superior to the trachea and inferior to the pharynx.

2. Keeps particles from entering the trachea and also houses the vocal cords.

3. Vocal cords.a) The upper pair is the false

vocal cords.b) The lower pair is the true

vocal cords.c) During swallowing, the

false vocal cords and epiglottis close off the glottis.

IV. Lower Respiratory TractB. Trachea

1. Extends downward from larynx and splits into right and left bronchi.

2. Inner wall lined with ciliated mucous membrane (many goblet cells) to trap incoming particles.

3. The tracheal wall is supported by 20 incomplete cartilaginous rings.

IV. Lower Respiratory TractC. Bronchial Tree

1. Branched tubes leading from the trachea to the alveoli.

2. Begins with the two primary bronchi, each leading to a lung.

3. Primary Bronchi Bronchioles Alveolar Ducts Alveoli

4. Gas exchange between the blood and air occurs through the thin epithelial cells of the alveoli.

IV. Lower Respiratory TractD. Lungs

1. Spongy, cone-shaped

2. Enclosed by the diaphragm and thoracic cage.

3. The bronchi and large blood vessels enter each lung.

4. The right lung has three lobes, the left has two.

5. Lobes are composed of lobules

V. Breathing MechanismA. Ventilation (breathing)-

composed of inspiration and expiration.

B. Inspiration1. Diaphragm and

intercostal muscles contract

2. Air pressure inside the lungs is decreased by increasing the size of the thoracic cavity.

3. Higher pressure air flows in from the outside.

V. Breathing MechanismC. Expiration

1. Diaphragm relaxes

2. Elastic recoil of lung and muscle tissues

3. Also from the surface tension within the alveoli.

4. Forced expiration is aided by thoracic and abdominal wall muscles.

VI. Respiratory Air Volumes and Capacities

A. The measurement of different air volumes is called spirometry.

B. Air that enters and leaves the lungs during one respiratory cycle is the tidal volume.

C. Maximum forced inspiration is the inspiratory reserve volume.

D. Maximum forced expiration is the expiratory reserve volume.

VI. Respiratory Air Volumes and Capacities

E. Vital capacity = tidal volume + inspiratory + expiratory reserve.

F. A residual volume always remains in the lungs.

G. Vital capacity + residual volume = total lung capacity.

H. Anatomic dead space is air remaining in the

bronchial tree.

VII. Control of BreathingA. Factors Affecting Breathing

1. Chemicals2. Lung tissue stretching3. Emotional state

B. Respiratory Center1. Groups of neurons in the

brain stem.2. Central chemoreceptors

a) Sensitive to changes in the blood concentration of CO2 and [H+]

b) CO2 or [H+] concentrations = the breathing rate

VII. Control of BreathingC. Peripheral

chemoreceptors1. In the carotid sinuses

and aortic arch.2. Sense changes in

blood oxygen concentration.

3. Low O2 increases breathing rate and tidal volume increase.

4. Hyperventilation lowers the amount of carbon dioxide in the blood.

VII. Control of BreathingD. Alveolar Gas Exchanges

1. Alveoli- Tiny sacs at the distal ends of the alveolar ducts.

2. Respiratory Membranea) Components

1) Epithelial cells of the alveolus

2) Endothelial cells of the capillary

3) The two fused basement membranes of these layers.

b) Gas exchange occurs across this respiratory membrane.

VIII. Gas TransportA. Oxygen Transport

1. Over 98% of oxygen is carried in the blood bound to hemoglobin, producing oxyhemoglobin.

2. Oxyhemoglobin is unstable and gives up its oxygen in low O2 areas.

3. More oxygen is released as CO2 increases, as the blood becomes more acidic, and as blood temperature increases.

4. A deficiency of oxygen reaching the tissues is called hypoxia.

VIII. Gas TransportB. Carbon Dioxide Transport

1. Bound to RBC as carbaminohemoglobin

2. Dissolved in plasma as bicarbonate ions.

a) The enzyme carbonic anhydrase is in RBCs

b) Enzyme combines CO2 with water forming carbonic acid

VIII. Gas Transport3. Carbonic acid dissociates, releasing bicarbonate and

hydrogen ions.

4. Most CO2 is transported as bicarbonate.

5. Carbaminohemoglobin releases its CO2 which diffuses out of the blood into the alveolar air.