The Respiratory System

Chapter 22

Objectives

1. SC.912.L.14.44 - Describe the physiology of the respiratory system including the mechanisms of ventilation, gas exchange, gas transport, and the mechanisms that control the rate of ventilation.

2. SC.912.L.14.44 - Describe the physiology of the respiratory system including the mechanisms of ventilation, gas exchange, gas transport, and the mechanisms that control the rate of ventilation.

3. SC.912.L.18.6 - Discuss the role of anaerobic respiration in living things and in human society.

Functions

1. Provides extensive gas exchange surface area between air and circulating blood

2. Moves air to and from exchange surfaces of lungs

Functions

3. Protects respiratory surfaces from outside environment

4. Produces sounds5. Participates in

olfactory sense

Organization

• Upper Respiratory System– above the larynx

• Lower Respiratory System– below the larynx

Organs (Upper)

• Nose– filters air

• Sinuses– warm and

moisten air

• Pharynx

Larynx

• Voice box• Made of cartilage,

surrounds the glottis– Adam’s apple

• Epiglottis– folds back over the glottis during

swallowing– prevents entry of food & liquids into the

respiratory tract

Sound Production

• Air passes through the glottis– vibrates vocal

folds– produces sound

waves

Organs (Lower)

• Trachea– windpipe–made of 15-20

rings of cartilage

• Lungs:– bronchi– bronchioles– alveoli

Lobes of the Lungs

• Lungs have lobes separated by deep fissures

• Right Lung– 3 lobes

• Left Lung– 2 lobes– cardiac notch

Respiration

• External respiration– includes all processes involved in

exchanging O2 and CO2 with the environment

• Internal respiration– involves the uptake of O2 and production

of CO2 within individual cells

Respiration

• C6H12O6 + 6O2 → 6CO2 + 6H2O + ATP

Accessory Structures

• Diaphragm– contraction

results in inhalation

– relaxation results in exhalation

• Vocal cords

Gas Exchange

• Occurs between alveolar air and capillary blood

• Depends on:– partial pressure of the

gases– diffusion of molecules

between gas and liquid

Composition of Air

• Nitrogen (N2) about 78.6%

• Oxygen (O2) about 20.9%

• Water vapor (H2O) about 0.5%

• Carbon dioxide (CO2) about 0.04%

Hemoglobin

• O2 binds to iron ions in hemoglobin molecules

• Carbon Monoxide (CO)– binds strongly to

hemoglobin– takes the place of O2

– can result in carbon monoxide poisoning

Changes in R.S. at Birth

1. Before birth:– pulmonary vessels

are collapsed– lungs contain no air

2. During delivery:– placental

connection is lost– blood PO

2 falls

– PCO2 rises

Changes in R.S. at Birth

3. At birth:– newborn overcomes force of surface

tension to inflate bronchial tree and alveoli and take first breath

Changes in R.S. at Birth

4. Large drop in pressure at first breath:– pulls blood into

pulmonary circulation– closing foramen ovale

and ductus arteriosus– redirecting fetal blood

circulation patterns

5. Subsequent breaths:– fully inflate alveoli

Effects of Aging

1. Elastic tissues deteriorate:– reducing lung compliance– lowering vital capacity

2. Arthritic changes:– restrict chest movements– limit respiratory minute

volume

3. Emphysema:– affects individuals over age 50– depending on exposure to

respiratory irritants (e.g., cigarette smoke)

Coordination of Respiratory & Cardiovascular Systems• Improves

efficiency of gas exchange

• Increases respiratory drive

• Raises cardiac output and blood flow