Structure and Functions of the Respiratory – PST04103 Human Anatomy and Physiology

NTA Level 4 • Semester 1 • PST04103

Structure and Functions of the Respiratory

Human Anatomy and Physiology • Source Session/Topic 24
Full source-text version: all educational wording from the extracted learning source is retained; only presenter/tutor metadata and web-layout noise are removed, while formatting is improved for readability.

Session 24: Structure and Functions of the Respiratory

System

Total Session Time: 120 minutes

Prerequisites

• None

Learning Tasks

By the end of this session students are expected to be able to:

• Define the Respiratory System
• Explain the Structure and Function of the Upper Respiratory Tract
• Explain the Structure and Function of the Lower Respiratory Tract

Resources Needed:

• Flip charts, marker pens, and masking tape
• Black/white board, chalk and whiteboard markers
• Overhead projector and computer

SESSION OVERVIEW

|Step |Time |Activity/ |Content |

| | |Method | |

|1 |05 minutes |Presentation |Introduction, Learning Tasks |

|2 |05 minutes |Presentation |Definition of Respiratory System |

| | |Brainstorming | |

|3 | |Presentation |Structure and Functions of the Upper|

| |60 minutes |Small Group |Respiratory System |

| | |Discussion | |

|4 | |Presentation |Structure and Functions of the Lower|

| |40 minutes |Small Group |Respiratory System |

| | |Discussion | |

|5 |05 minutes |Presentation |Key Points |

|6 |05 minutes |Presentation |Evaluation |

SESSION CONTENTS

STEP 1: Presentation of Session Title and Learning Tasks (5 minutes)

READ or ASK students to read the learning tasks and clarify

ASK students if they have any questions before continuing

STEP 2: Definition of Respiratory System (5 minutes)

|Activity: Brainstorming (5 minutes) |

| |

|Ask students to brainstorm on the following question: |

| |

|What is respiratory system? |

| |

|ALLOW few students to respond |

| |

|WRITE their responses on the flip chart/ board |

| |

|CLARIFY and SUMMARISE by using the content below |

• The respiratory tract is the part of the anatomy that is responsible with

the process of respiration in human body

• Primarily, oxygen is absorbed from the atmosphere into the body and

carbon dioxide is expelled from the body

• The respiratory system may be divided into the upper respiratory tract

and the lower respiratory tract.

STEP 3: Structure and Functions of the Upper Respiratory System

(60 minutes)

|Activity: Small Group Discussion ( 30 minutes) |

| |

|DIVIDE students into small manageable groups |

| |

|ASK students to discuss on the following question |

|What are the structures and functions of upper respiratory system? |

| |

|ALLOW students to discuss for 15 minutes |

| |

|ALLOW few groups to present and the rest to add points not mentioned |

| |

|CLARIFY and SUMMARIZE by using the contents below |

• The organs of the upper respiratory system are located outside of the

thorax and consists of the nose, pharynx and larynx

• Nose

o Is made up of bone and cartilage covered with skin, and lined with hairs

within the nostrils. The hairs help to block dusts entry

o The two nasal cavities are within the skull, separated by the nasal

septum, which is a bony plate made of the ethmoid bone and vomer

o The nasal mucosa is ciliated epithelium with goblet cells which produce

mucus

o The mucus produced help to trap bacteria and particles from the air

o There are three shelve like bones called conchae project from the lateral

wall of each nasal cavity

o In the upper nasal cavities are the olfactory receptors, which detect

vaporized chemicals that have been inhaled.

o Paranasal sinuses:

▪ Air cavities in the maxillae, frontal, sphenoid, and ethmoid bones
▪ Are lined with ciliated epithelium, and the mucus produced drains

into the nasal cavities.

▪ The functions of the paranasal sinuses are to lighten the skull and

provide more vibrating air for the voice.

• Functions of the nose

o Respiration (breathing)

▪ The nose humidify, warm, filter and clean the air

o Reception and elimination of secretions from the nasal mucosa, paranasal

sinuses, and nasolacrimal ducts

o Olfaction (smelling) – is the organ of sense of smell

o It aids speech- this is enhanced by the presence of paranasal sinuses

• Pharynx

o It is a muscular tube posterior to the nasal and oral cavities and

anterior to the cervical vertebrae.

o It is divided into nasopharynx, oropharynx and laryngopharynx.

o Nasopharynx lies behind the nasal cavity.

▪ It is continuous with lining of the nose and consists of ciliated

columnar epithelium and the intermediate layer is fibrous tissue.

o Oropharynx; lies behind the oral cavity.

▪ It is lined with stratified squamous epithelium which is continuous

with lining of the mouth and oesophagus.

o Laryngopharynx also known as the hypopharynx, this is also lined with

moist stratified squamous epithelium.

• Functions of the pharynx

o Passageway for air and food

o Warming and humidifying air

o Protection

o Taste

o Facilitates Hearing

o The pharynx is also important in vocalization and Speech

• Larynx

o The larynx houses the vocal folds, and is situated just below the pharynx

between the root of the tongue and upper end of the trachea.

o The larynx consists of cartilages attaches to each other by ligaments and

membranes.

o The framework of the larynx is formed by nine cartilages (e.g. thyroid,

epiglottis) connected to one another by muscles, ligaments and membranes.

o The epiglottisis the uppermost cartilage. During swallowing, the larynx

is elevated, and the epiglottis closes over the top to prevent entry of

saliva and food to the larynx

• Functions of the larynx

o Speaking (speech)

▪ Sound production is primarily done by the focal folds

o Respiration (is the air passageway between pharynx and the trachea)

o Swallowing

▪ The epiglottis and vestibular folds prevent swallowed material from

moving into the larynx

STEP 4: Structure and Functions of the Lower Respiratory System

(40 minutes)

|Activity: Small Group Discussion ( 30 minutes) |

| |

|DIVIDE students into small manageable groups |

| |

|ASK students to discuss on the following question |

|What are the structures and functions of lower respiratory system? |

| |

|ALLOW students to discuss for 15 minutes |

| |

|ALLOW few groups to present and the rest to add points not mentioned |

| |

|CLARIFY and SUMMARIZE by using the contents below |

• The organs of the lower respiratory system are located inside of the

thorax and consists of the trachea, bronchial tree and lungs

• Trachea

o The trachea is about 4 to 5 inches long and extends from the larynx to

the primary bronchi.

o The wall of the trachea contains 16 to 20 C-shaped pieces of cartilage,

which keep the trachea open.

o The gaps in these incomplete cartilage rings are posterior, to permit the

expansion of the esophagus when food is swallowed.

o The mucosa of the trachea is ciliated epithelium with goblet cells.

• Bronchial Tree

o Are the branches of trachea that enters the lungs (primary bronchi)

o Their structures are like those of trachea, with C-shaped cartilages and

ciliated epithelium

o Within the lungs, the primary bronchus branches to secondary bronchi that

forms lobes of each lungs (three right, two left)

o The further branching of the bronchial tube if called bronchial tree

o The smallest branches are called bronchioles and are clinically important

in asthma

o Bronchioles have no cartilages and the smallest ones terminate in

clusters of alveoli, the air sacs of the lungs.

• Lungs and pleural membranes

o Lungs are located on either side of the heart in the chest cavity and are

encircled and protected by the rib cage

o The base of each lung rests on the diaphragm below; the apex (superior

tip) is at the level of the clavicle.

o On the medial surface of each lung there is an indentation called the

hilus, where the primary bronchus and the pulmonary artery and veins

enter the lung.

o The pleural membranes are the serous membranes of the thoracic cavity.

o The parietal pleura line the chest wall, and the visceral pleura are on

the surface of the lungs.

o Between the pleural membranes is serous fluid, which prevents friction

and keeps the two membranes together during breathing.

o Alveoli

▪ Are the air sacs of the lungs
▪ Is where there is oxygen carbon dioxide exchange
▪ In the spaces between clusters of alveoli is elastic connective

tissue, which is important for exhalation.

▪ Within the alveoli are macrophages that phagocytise pathogens or

other foreign material that may not have been swept out by the

ciliated epithelium of the bronchial tree.

[pic]

Source: Tortora G.J (2009)

Figure 20:1. Anterior

view of respiratory system

STEP 7: Key Points (5 minutes)

• Respiratory system is responsible with exchange of gases (oxygen and

carbon dioxide) in human body

• Respiratory system is lined with mucus and cilia for trapping

microorganisms and dusts

• Alveoli are functional units of lungs where exchange of gases takes place

STEP 8: Evaluation (5 minutes)

• What are the functions of respiratory system?
• What is the main function of the alveoli?
• What are the functions of upper respiratory system?
• What are the structures of lower respiratory system?

References

Seeley, R. R., Stephens, T. D., &Tate, P. (2003). Anatomy and Physiology.

(5th ed.).Boston:

McGraw-Hill.

Standring, S. (2008). Grays’s Anatomy; the anatomical basis of clinical

practice.(40th ed.).

Elservier: Churchill Livingstone.

Thibodeau, G. A., & Patton, K. T. (1999). Anatomy & Physiology. Mosby:

Hoffman

Press, Inc.

Tortora, G.J & Derrickson, B (2009). Principles of Anatomy and Physiology

12th Edition,

USA, John Wiley & Sons Inc, USA

Waugh, A., & Grant, A. (2006). Ross and Willson Anatomy and physiology in

Health and

illness. China: Churchill Livingstone Elservier

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