LESSON 24AS PE ANATOMY & PHYSIOLOGY

James BarracloughRespiratory System –

Maintenance of Oxygen Supply

Starter

http://www.bbc.co.uk/schools/gcsebitesize/pe/appliedanatomy/respiratory/1_anatomy_respiratorysys_act.shtml

Aims:

Objectives: by the end of the lesson learners will be able:

• Outline the structure of the respiratory system• Describe the process of external respiration• Explain the mechanics of breathing at rest & the respiratory muscles involved

Introduction: Respiratory System• Respiratory system is responsible for transportation of O2 via

lungs to body to fuel muscular contraction • As well as removing CO2 & lactic acid from blood via lungs• Working with CV system to ensure demand for O2 is satisfied • Average adult inhales & exhale approximately 12-15 breaths

per minute• External respiration involves movement of gases in & out of

lungs• Exchange of gases = PULMONARY DIFFUSION

COMPLETE ACTIVITY 1: 5 minutes

Structure of the Respiratory System

Complete Activity 2

Explain how air passes through respiratory system from nasal passages/mouth to alveoli (previous slide)

10 minutes

Activity 2 Answers: Passage of Air• Stage 1: Nasal passages: air drawn in through nose

Stage 2: Oral Pharynx & Larynx• Throat shared by respiratory & alimentary (digestive) tracts. Air goes past

larynx (voice box) into trachea (windpipe). When we swallow epiglottis closes over trachea

• Stage 3: Trachea: c.10cm long made of 18 C shaped cartilage rings, also lined with mucous membrane & ciliated cells (dust/dirt protection). Directs air into L/R bronchi

• Stage 4: Bronchi/bronchioles: subdivisions of trachea into lobar bronchi (3 feed each lobe on L & R). Further subdivide into bronchioles & again into terminal/ respiratory bronchioles

• Stage 5: Alveoli:• Responsible for gaseous exchange between lungs & blood • Alveolar walls v thin & lined with film of water to allow O2 to dissolve• Each alveolus (sing.) surrounded by capillary network → smooth passage of O2 into pulmonary

capillaries• Each lung has c. 150m alveoli = v big area to exchange gases

http://www.youtube.com/watch?v=sU_8juD3YzQ&NR=1&feature=fvwpCOMPLETE ACTIVITY 3:

10 MINUTES

Activity 3 AnswersBreathing in... Breathing out...

Intercostal muscles contract Intercostal muscles relax

Ribs move upwards Ribs move downwards

Diaphragm contracts Diaphragm relaxes

Chest expands Chest moves downwards

Air pressure decreases Air pressure increases

Air is drawn in Air is forced out

Activity 3 Answers continued...

3 benefits of breathing in through your nose:

1. Mucous membranes & blood capillaries moisten/warm inspired air

2. Ciliated epithelium filters dirt to throat for removal

3. Choncae (small bones) increase surface area of cavity to improve efficiency

Pressure Changes during Inspiration(a) Prior to inspiration, the intrapulmonary pressure is 760 mmHg (b) The intrapulmonary pressure decreases to about 757 mm Hg as the thoracic cavity enlarges, and atmospheric pressure forces air into the airways

Respiration During Exercise• Inspiration: more air can fill lungs as

STERNOCLEIDOMASTOID, PECTORALIS MINOR & SCALENI muscles increase thoracic cavity even more

• Expiration: process becomes more active as INTERNAL INTERCOSTAL MUSCLES pull ribs down to increase ventilation rate (assisted by abdominals & latissimus dorsi)

Extension Activity AnswersComponent Inhaled air Exhaled air

Oxygen 21% 16%

Carbon dioxide

0.04% 4%

Nitrogen 79% 79%

Extension Activity Answers continued...

Inhaled air contains:• more oxygen used to create energy• less carbon dioxide than…Exhaled air which contains:• more carbon dioxide produced as a waste product of

energy production• less oxygen as it has been used in respiration

Acute effects:

Chronic effects:

Recap Activity

Mind Map

Homework

Next Lesson…

• Describe the changes in mechanics of breathing during physical activity• Explain how the respiratory control centre regulates the mechanics of breathing at rest and during exercise• Outline the processes of gaseous exchange that takes place between the alveoli and blood, and between the blood and tissue cells.• Explain the changes in gaseous exchange that take place between the alveoli and blood, and between the blood and tissues cells during physical activity