Anatomy & Physiology 2 Canale

Respiratory System: Exchange of Gases

Why is it so hard to hold your breath for a long time?

Discuss! : )

Every year carbon monoxide poisoning kills 500 people and sends another

40,000 to hospital emergency rooms. Why is carbon monoxide so deadly?

Human Respiratory System

Figure 10.1

Nose

Passageway for air

Mouth

Passageway for food and air

Epiglottis

Covers larynx during swallowing

Pleural membranes

Cover the lungs and line the chest cavity

Lung

Organ of gas exchange

Intercostal muscle

Moves ribs during respiration

Nasal cavity

Filters, warms, and moistens air

Larynx (Voice box)

Production of sound

Trachea (Windpipe)

Main airway

Bronchi

Branching airways

Pharynx (Throat)

Common passageway for air, food, and liquid

Alveoli

Air sacs for gas exchange

Right lung Left lung Rib

Diaphragm

Skeletal muscle of respiration

UP

PE

R R

ES

PIR

AT

OR

Y

TR

AC

T

LO

WE

R R

ES

PIR

AT

OR

Y

TR

AC

T

Animation—The Human Respiratory System

Respiration Processes

• Breathing (ventilation): moving air in and out of lungs

• External respiration: gas exchange between air and blood

• Internal respiration: gas exchange between blood and tissues

• Cellular respiration: oxygen use to produce ATP, carbon dioxide as waste – inside the cell (mitochondria! )

The Upper Respiratory Tract

Figure 10.2

Nasal cavity

External nose

Nostril

Tongue

Larynx

Esophagus

Epiglottis

Glottis

Pharynx

Opening of the

auditory tube

Sinuses

Trachea

Upper Respiratory Tract

• Functions

1. Passageway for respiration

2. Receptors for smell

3. Filters larger foreign material from incoming air

1. Moving cilia – hair-like projections – the mucus traps dust and foreign particles and cilia moves this to the back of nasal cavity where we cough it or swallow it.

4. Moistens and warms incoming air

5. Resonating chambers for voice

The Lower Respiratory Tract

Figure 10.3

Trachea

Bronchioles

Left

bronchus

Clusters

of alveoli

Larynx

Right

bronchus

Lower Respiratory Tract

• Functions

1. Larynx: maintains an open airway, routes food and air appropriately, assists in sound production

2. Trachea: transports air to and from lungs

3. Bronchi: branch into lungs

4. Lungs: transport air to alveoli for gas exchange

Gas Exchange Between the Blood and Alveoli

Figure 10.8a (1 of 3)

Gas Exchange Between the Blood and Alveoli

Figure 10.8a (2 of 3) and (3 of 3)

Exchange due to partial pressures /concentration gradients

Breathing: Pressure Gradient

• Inspiration AND expiration: air in AND air out cycle 1. Relaxed state

• Diaphragm and intercostal muscles relaxed

2. Inspiration

• Diaphragm contracts, pulling muscle down; intercostal muscles contract, elevating chest wall and expanding volume of chest, lowering pressure in lungs, pulling in air

3. Expiration

• Muscles relax; diaphragm resumes dome shape; intercostal muscles allow chest to lower, resulting in increase of pressure in chest and expulsion of air

Respiratory Cycle

Figure 10.9

Lung Volumes and Vital Capacity

Tidal volume Volume of air inhaled and exhaled in a single

breath

Dead space volume Volume of air that remains in the airways and

does not participate in gas exchange

Vital capacity Maximal volume that can be exhaled after

maximal inhalation

Lung Volumes and Vital Capacity

Inspiratory reserve volume Volume of air that can be inhaled beyond the tidal

volume

Expiratory reserve volume Volume of air that can be forcibly exhaled beyond

the tidal volume

Residual volume Volume of air remaining in the lungs, even after a

forceful maximal expiration

Measured by spirometer

Measurement of Lung Capacity

Figure 10.10a

Gas Exchange and Transport: A Passive Process

Gases diffuse according to their partial pressures External respiration: gases exchanged between air

and blood Internal respiration: gases exchanged with tissue

fluids Oxygen transport: bound to hemoglobin in red

blood cells or dissolved in blood plasma Carbon dioxide transport: dissolved in blood

plasma, bound to hemoglobin, or in the form of plasma bicarbonate

How O2 and CO2 are Transported in Blood

Figure 10.12 (1 of 2)

How O2 and CO2 are Transported in Blood

Figure 10.12 (2 of 2)

Regulation of Breathing: Nervous System Involvement

• Respiratory center in the medulla oblongata

– Establishes basic breathing pattern

• Chemical receptors

– Monitor carbon dioxide, hydrogen ions, and oxygen levels

• Medulla

– Sensitive to hydrogen ions in cerebrospinal fluid resulting from carbon dioxide in blood

Regulation of Breathing

Figure 10.13

Regulation of Breathing: Nervous System Involvement

• Carotid and aortic bodies

– Sensitive to carbon dioxide, pH, and oxygen levels

• Conscious control

– Resides in higher brain centers

– Ability to modify breath

Disorders of Respiratory System

• Reduced air flow 1. Asthma – spasmodic contraction of bronchi 2. Emphysema - alveoli are permanently impaired 3. Bronchitis – inflammation of the bronchi

• Infections 1. Pneumonia – bacterial or viral infection – inflamed lungs 2. Tuberculosis – bacteria Mycobacterium tuberculosis 3. Botulism - Clostridium botulinum bacteria

Disorders: 1. Lung cancer 2. Congestive heart failure 3. Cystic fibrosis

True or false? Production of mucus is not a normal part of the

respiratory system.

True

False

True or false? The pulmonary artery carries blood that is low in oxygen.

• True

• False

Doctors measure lung function by having a person inhale and then exhale forcibly into a device called a spirometer. What does a

spirometer measure?

A. The volume of air that a person can breathe in and out in a single breath

B. How quickly air can be moved in and out of the lungs

C. How much muscle the lungs have

D. Both A and B

The chemicals in tobacco smoke ______.

A. increase mucus production

B. destroy cilia

C. cause mucus pooling, leading to infections

D. All the above

Gas exchange in the respiratory system occurs in the __________.

A. trachea

B. bronchiole tree

C. alveoli

D. pleural cavity

When you take a deep breath then hold it, you are using your

__________.

A. tidal volume

B. inspiratory reserve volume

C. expiratory reserve volume

D. vital capacity

Most of the carbon dioxide carried in the blood is in the form of _________.

A. oxyhemoglobin

B. dissolved carbon dioxide

C. carbonic acid

D. bicarbonate

The principle chemical monitored in the respiratory system is __________.

A. oxygen

B. carbon dioxide

C. carbonic acid

D. oxyhemoglobin