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Chapter 18

Human

Respiration

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Human Respiration Involves the process of cellular

respiration and gas exchange

a) cellular respiration:

glucose + O2 H2O + CO2 + 36 ATP’s

b) gas exchange:

exchange of gases between the internal and external environment with

the use of lungs

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(I) Human Respiratory System

Composed of a network of passageways which permits air to flow from the external

environment and into the lungs

Human Respiratory System

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Nasal Cavity The nose Lined with a ciliated mucus

membrane The cilia and mucus: 1. Filters air 2. Warms air 3. Moistens air

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Pharynx

Known as the throat regionIt is an area in which both air

and food pass through

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Larynx Also called the Adam’s apple Humans use the larynx as a

voice box which contains vocal cords that vibrate and produce sound as air passes through

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Epiglottis

A cartilaginous flapIt “covers” the trachea when

swallowing food

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Trachea Known as the windpipe Kept open by rings of

cartilage Lined with a ciliated mucus

membrane One cigarette paralyzes the

cilia for 20 minutes

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Bronchi Bronchus = singular Trachea divides into two major

divisions known as bronchi The bronchi contain cartilage

rings as well The bronchi subdivide many

times forming smaller tubules known as bronchioles

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Bronchioles

Lack cartilage ringsTiny bronchioles subdivide

and terminate (end) with structures known as alveoli

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Alveoli Are thin, moist and surrounded by

capillaries Are the functional units for gas

exchange between the lung and the blood

Alveoli increase surface area for gas exchange

O2 diffuses into the blood from the alveoli and CO2 and water diffuse out of the blood and into the alveoli

Gas Exchange at the Alveolus

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Diaphragm

Muscle that forms the floor of the chest cavity

Aids in the breathing process

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(II) Breathing Process Lungs are highly elastic (stretchable) Breathing is controlled by the medulla Movement of the diaphragm and ribcage

causes pressure change in the chest cavity which moves air into and out of the lungs

The breathing rate is controlled by the concentration of CO2 in the blood

Inhalation- breathe in Exhalation- breathe out

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(IV) Gas Exchange1. In the blood, hemoglobin binds

with oxygen from the alveoli to form oxyhemoglobin (HbO2)

2. Carbon dioxide is carried primarily in the plasma of the blood in the form of bicarbonate ions (HCO3)

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Diseases of the

Respiratory System

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Bronchitis

Inflammation of the membrane of the bronchial

tubes

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Asthma

An allergic response characterized by

constriction of the bronchial tubes

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Emphysema Disease in which the walls of

the alveoli breakdown, decreasing surface area for

gas exchange Characterized by shortness of

breath, difficulty in breathing, and decreased lung capacity

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Pneumonia

The alveoli become filled with fluid, preventing gas

exchange between the alveoli and the capillaries