Respiratory System

Question 1

Respiratory System

Answer 1

• provides route of O2 into the body and CO2 out of the body
• consists of air passages and lungs
• air passages connect lungs with air outside the body through openings at the nose and mouth
• blood carries O2 from lungs to cells
• blood returns CO2 from cells to lungs

Question 2

Anatomy of the respiratory system

Answer 2

• nasal cavity - nose
• pharynx
• larynx
• trachea
• two bronchi (1 bronchus in each lung)
• bronchioles
• alveoli
• lungs

Question 3

Nasal cavity

Answer 3

• main air route entry
• anterior nares (nostrils) separated into right and left by midline septum, part cartilage and part bone.
• posterior nares found at the back of the nasal cavity and form entry of the naso-pharynx
• lateral walls formed by maxillae of the skull
• nasal lining is ciliated columnar epithelium

Question 4

Function of nasal cavity

Answer 4

• warm, moisten and filter air
• protect underlying epithelium via mucous membrane
• smell - conveyed by olfactory nerves to brain

Question 5

Pharynx (throat)

Answer 5

• tube like structure 12-14cm long from base of skull to oesophagus
• posterior to nasal and oral cavities
• made of muscle and lined with mucous membrane
• soft palate acts as valve between nasal and oropharynx - closing nasopharynx during swallowing and oropharynx during respiration

Question 6

3 parts of pharynx

Answer 6

Nasopharynx:
- nasal portion of pharynx
- contain pharyngeal tonsils (adenoids) prominent in young children and shrink with age

Oropharynx:
- oral part of the pharynx
- contains palatine tonsils

Laryngopharynx:
- laryngeal part of pharynx

Question 7

Structure of pharynx

Answer 7

3 layers of tissue:
- mucous membrane lining
- fibrous tissue
- smooth muscle tissue

Question 8

Functions of pharynx?

Answer 8

• Passageway for air and food
• Warming & humidifying
• Taste
• Hearing- via auditory tube
• Protection- via lymphatic tissue (Pharyngeal & Laryngeal Tonsils)
• Helps with speech

Question 9

Larynx (voice box)

Answer 9

• lies at root of tongue and extends to trachea
• after puberty - grows larger in males (Adam’s apple) = deeper voice
• lined by ciliated mucous membrane
• triangle shape consisting largely of cartilage and muscle
• interior aspect houses vocal cords

Question 10

Function of larynx

Answer 10

• Sound
• Protection of respiratory tract - ensures food
  passes into the oesophagus and not into the
  respiratory passages via Epiglottis- closes over Larynx when eating
• Passageway for air between pharynx & trachea
• Humidify, warming and filter air

Question 11

Trachea

Answer 11

• continuation of larynx
• runs vertically down thoracic cavity - divides into right and left bronchi
• 10-11cm in length
• lies in front of oesophagus
• Composed of a series of ‘C’ shaped cartilage - connected by fibrous tissue - keeps trachea constantly open

Question 12

Trachea layers

Answer 12

• outer layer - fibrous and elastic tissue encloses cartilage
• middle layer - cartilage and bands of smooth muscle
• inner. Layer - lined with ciliated columnar epithelium, containing goblet cells

Question 13

Function of trachea

Answer 13

• support - won’t collapse - due to cartilage
• regular beating of cilia - wafts mucus with particles up towards larynx
• cough reflex, abdominal and respiratory muscles contract to expel mucous/foreign material.
• warming, humidifying and filtering of air.

Question 14

Two bronchi

Answer 14

• formed when trachea divides (similar structure to trachea)
• right - 2.5cm long, wider and shorter, divides into 3, one to each lobe of the lung
• left - 5cm long, narrower, divides into 2 branches, one to each lobe
• structure and function = same as trachea
• bronchi subdivide into bronchioles - alveolar ducts - then finally alveoli (tiny air sacs)

Question 15

Bronchioles

Answer 15

• minute branch of bronchi
• cartilage diminishes and muscle takes over
  Function:
• warming and humidifying
• defence against microbes

Question 16

Alveoli

Answer 16

• tiny air sacs
• alveoli surrounded by network of capillaries
• exchange of gases during respiration takes place here.

Question 17

Function of alveoli - external respiration

Answer 17

• exchange of gases by diffusion between alveoli and the blood
• CO2 diffuses from venous blood into the alveoli - using same process O2 diffuses from alveoli into blood to be transported throughout the body

Question 18

Lungs

Answer 18

• 2 lungs each side of midline in thoracic cavity
• cone shaped
• right - divided into 3 lobes
• left - divided into 2 lobes (to accommodate heart)

Question 19

Pleura

Answer 19

• serous membrane that folds back on itself forming 2 layered membrane within the lungs:
  Inner visceral pleura:
• adheres to each lung
  Outer parietal pleura:
• adheres to chest wall - diaphragm

Pleural cavity:
- lies between, contains serous fluid

Question 20

Intercostal muscles

Answer 20

• thin sheets of muscle running across the gaps between ribs
• contraction of these muscles causes the rib cage to expand upwards and outwards
• normal adult respiratory rate is 14-15 breaths per minute

Question 21

Disorders of the respiratory system?

Answer 21

• Common cold
• Pharyngitis
• Laryngitis
• Bronchitis
• Emphysema
• Lung abscess
• n.b. inhaled instruments/materials in
  the dental surgery