Topic 2: respiratory system structure and function

purpose of respiratory system

- to deliver o2 to body cells

- to eliminate co2 the body cells produce

- respiration (internal and external)

what is external respiration

gas exchange of o2 and co2 bw bodys cells and external environment

4 steps of repspiration

external:

1. ventialtion (movement of air in and out the lungs)

2. O2 and co2 exchange bw alveolar air and pulmonary capillary blood (pulmonary circulation)

3. blood transports o2 and co2 bw lungs and tissues (systemic circulation)

4. O2 and CO2 exchanged between tissues and blood by process of diffusion across systemic (tissue) capillaries

wasserman gears of life

depicst how all types of respiration are occuring simulatenously liek gears that are powering eachother

does the respiratory system only have respiratory funciton

no has many other non-respiaroty funciton

eg. enables speech, singing

eg. roate fpr water loss adn heat elimintation

eg. smell

structures of the respiratory system (airway brnaching)

1. pharynx (esophogeous and larynx)

2. trachea

3. lungs (L & R lobes)

conducting zone:

4. bronchi

5. bronchioles

6. terminal bronchioles

respiratory zone:

7. respiratory bronchioles

8. alveolar ducts

9. alveolar sacs

where are the lungs located

thoracic cavity - air tight space shared with heart and bloodvessels

airway branching wiht numbers and

1 trachea%

2-8 bronchi%

16-23 bronchioles*%

6000 terminal bronchioles*%

50'000 respiratory bronchioles*%

alveolar ducts

8'000'000 alveolar sacs

*smooth muscle → can bronchoconstrict/dilate (suffix "iole")

% lined with cillia thta excrete mucus that traps particles then pushes then upwards

structure of the lungs and what are they made of

2 lungs

Each divided into seperated into many lobes each supplied by one of the bronchi

Made of?

Lung consists of a series of highly branched airways, the alveoli, the pulmonary blood vessels, and large quantities of elastic connective tissue

what are airwyas (name first 6)

= tubes that carry air bw atm and air sacs

Nasal passage

Pharynx

Larynx

Trachea

Right and left bronchi

bronchioles

structure of trachea

-rigid

- non muscular

- made of cartilage rins

structure of bronchioles

- lies with smooth muscle innervated by autonomic ns

- no cartilage to hold open

- sesnitive to certain hormones and locla chemicals

What do puffers do?

b agonist that causes bronchodilation of small airways

fuction of alvoli

inflatable savs where gas exchange occurs

structure of alveoli (what cells)

- thin walled - single layer of flattened type 1 alveolar cells

- each surroundd by pulmoary capilaries

- type 2 alvolar cells secrete pulmonary surfactant to reduce surface tesion

- alvolar macrophages guarding the lumen

- pores of Kohn permitign collateral ventilation bw adjacent alveoli

the chest wall

Forms the outside of the thoracic cavity

structure:

- formed by 12 pairs of ribs (protects lungs & heart), sternum and thoracic vertabrae

- contains muscles that create pressure to cause airflore (chest wall pushing outwards opposing inwards elasticity of lungs)

Muscles of inspiration

Sternocleidomastoid

Scalenes

External intercostals

Parasternal intercostals

Diaphragm*

Muscles of expiration

Internal intercostals

External abdominal oblique

Internal abdominal oblique

Transverse abdominus

Rectus abdominus

diaphram

Dome between the chest and the gastric cavity:

accounts for 75+% of the enlargement of the throacic cavity during eupnea by contracting and flattening

what happens when the thoracic cavity expands durign inpiration

- diaphram contracts ccausing...

- intrapleural pressure decreases

- lungs want to expand to fill this lower pressure area

- volume of lungs ↑ so Palv ↓ below Patm

- pressure gradient causes airflow into lungs

(accesory insp msucles further enlarge thoracic cavity

expiration onset steps

- inspiratory msucles relax, diaphram relaxes and elastic recoil of lungs decrease size of chest cavity

- causes intrapleural pressure and Palv to ↑

- pressure gradient cause airflow out of lung