Respiratory System (15)

Question 1

What happens to the air that enters the lungs?

Answer 1

> Condition of air entering lungs varies depending on external environment e.g. if it is cold/hot
As it moves into the lungs it is warmed/cooled to body temp and is then moistened and cleaned
Blood then transports the gases between the lungs and cells of the body

Question 2

What is the main role of the respiratory system?

Answer 2

> To supply the body with oxygen and dispose of carbon dioxide
Most energy is derived from chemical reactions which take place in the presence of oxygen and carbon dioxide

Question 3

What is external respiration?

Answer 3

> The exchange of gases between blood and lungs
O2 diffuses from lungs to blood
CO2 diffuses from blood to lungs

Question 4

What is internal respiration?

Answer 4

> Exchange of gases between blood and cells
O2 diffuses from blood to cells
CO2 diffuses from cells to blood

Question 5

What are the organs involved in the respiratory system?

Answer 5

Nose
Pharynx
Larynx
Trachea
2 bronchi
Bronchioles
Alveoli
2 lungs

Question 6

What is the nose?

Answer 6

> First respiratory passage that air passes through
Function= begin warming, moistening and filtering air
Very vascular

Question 7

Functions of the nose- filtering and cleaning

Answer 7

> Hairs trap larger particles and the smaller particles (dust and microbes) stick to mucus
Mucus protects epithelium from irritation and prevents drying
Cilia waft mucus towards nose and throat to be swallowed/expectorated

Question 8

Functions of the nose- humidification

Answer 8

> As air moves over moist mucosa, becomes saturated with water vapour
Irritation of nasal mucosa results in sneezing to expel irritants

Question 9

Functions of the nose- olfaction

Answer 9

> Organ for sense of smell
Nerve endings to detect smell are found in roof of nose
Olfactory nerve carries smell nerve impulses to the brain to be interpreted

Question 10

What are the functions of the pharynx?

Answer 10

> A passageway for air and food- air passes through nasal and oral sections and food passes through oral and larangeal sections
Warming and humidifying- air warmed and moistened as it passes towards lungs
Hearing- Auditory tube allows air to enter the middle ear. Hearing depends on presence of air at atmospheric pressure on either side of the tympanic membrane (eardrum)
Protection- Lymphatic tissue of tonsils produce antibodies in response to swallowed/inhaled antigens
Speech- Acts as a resonating chamber for speech sounds

Question 11

What is the pharynx?

Answer 11

> 12-14cm
Tube extending from base of skull to level of 6th cervical vertebra
Lies behind the nose, mouth and larynx

Question 12

What is the nasopharynx?

Answer 12

> Behind the nose
Has auditory tubes on the lateral walls leading to each middle ear
On posterior walls, there are pharyngeal tonsils (adenoids)
Most prominent in children up to 7yrs and gradually astrophy after this

Question 13

What is the Oropharynx?

Answer 13

> Behind the mouth

> Lateral (side) walls have collections of lymphoid tissue called palatine tonsil

Question 14

What is the laryngopharynx?

Answer 14

> Extends from oropharynx and continues as oesophagus

Question 15

What is the larynx?

Answer 15

> Voice box
Extends from laryngopharynx to trachea
After puberty, grows larger in males (adams apple) and deeper voice sounds
Composed of several irregularly shaped cartilages

Question 16

What are the functions of the larynx?

Answer 16

1) Produce sound- Sound has properties of pitch, volume and resonance
> Pitch- Depends on length and tightness of vocal cords- lengthen at puberty which is why boys’ voice drops
> Volume- Depends on force with which the vocal chords vibrate
> Resonance/tone- Shape of mouth, position of tongue and lips, facial muscles and air in sinuses
2) Speech- Occurs during expiration when sounds produced by vocal chords are manipulated with tongue, cheeks and lips
3) Protection of lower respiratory tract- During deglutition (swallowing), epiglottis covers over the larynx which ensures food passes into oesophagus not into the lower respiratory tract
4) Passageway of air
5) Humidifying, filtering and warming
6) Closed during coughing, sneezing and Valsalva’s manoeuvre

Question 17

What is Valsalva’s manoeuvre?

Answer 17

1) Air is temporarily held in lower respiratory tract by closing the glottis
2) Causes intra-abdominal pressure to rise when abdominal muscles contract
3) Helps to empty the rectum
4) Acts as a splint to stabilise the trunk when lifting heavy loads

Question 18

What is the trachea?

Answer 18

> Also known as the windpipe
Continuation of the larynx and divides at the carina into the left and right primary bronchi
One bronchus goes to each lung
Carina is rich in sensory nerve endings and irritation to this can cause a powerful cough reflex

Question 19

What are the functions of the trachea?

Answer 19

1) Support and patency- arrangement of cartilage and elastic tissue prevents obstruction of airway when head and neck move. Absence of cartilage at the back allows the trachea to indent as food is swallowed and moves down the oesophagus
2) Muscociliary escalator- regular beating of cilia moves debris toward the surface to larynx where it can be swallowed/coughed up
3) Cough reflex- Nerve endings in larynx, trachea and bronchi are sensitive to irritation which leads to air release under pressure, expelling mucus and/or foreign material from mouth
4) Warming, humidifying and filtering

Question 20

What are the bronchi and bronchioles?

Answer 20

> 2 bronchi formed when trachea divides
Right bronchus- wider, shorter, more vertical than the left, more prone to obstruction. After entering lung at hilum, divides into 3 branches, one to each lobe, each branch then divides into many smaller branches
Left bronchus- narrower. After entering lung at hilum, divides into 2 branches, one to each lobe, each branch then divides into progressively smaller airways
Controlled by autonomic nervous system

Question 21

What are the functions of the bronchi and bronchioles?

Answer 21

1) Control of air entry- Diameter of respiratory passageways alters by contraction/relaxation of involuntary muscles in their walls which regulates the amount of air entering the lungs
2) Warming and humidifying
3) Support and patency
4) Removal of particles
5) Cough reflex

Question 22

What is the respiratory membrane?

Answer 22

> An air-blood barrier which is composed of alveolar and capillary walls and their fused basal laminas
Alveolar walls are a single layer of type 1 epithelial cells and they permit gas exchange by simple diffusion
Type 2 cels secrete surfactant
Gas exchange takes place across this membrane

Question 23

What are alveoli?

Answer 23

> Air sacs
Gas exchange takes place across the respiratory membrane which is made from alveolar wall and capillary wall
Surrounded by fine elastic fibres
Contain open pores which connect adjacent alveoli and allow air pressure throughout the lung to be equalised
Macrophages are present which keep alveolar surfaces sterile
Surrounded by dense network of capillaries

Question 24

What is the structure of the lungs?

Answer 24

> 2 of them, one each side of the midline
In the thoracic cavity
Cone shaped
Apex- rounded, rises into the neck
Base- concave, semilunar in shape, sits on thoracic surface of diaphragm
Costal surface- convex, broad outer surface of the lungs which lies against the costal cartilages, ribs and intercostal muscles
Medial surface- Concave, contains roughly triangular shaped area called the hilum
Has structures such as bronchus, major blood vessels, lymph vessels and nerve supply

Question 25

How are the lungs divided?

Answer 25

> Area between lungs is mediastinum
R lung divided into 3 lobes- superior, middle and inferior
L lung divided into 2 lobes- superior and inferior

Question 26

What is the pleura?

Answer 26

> Closed sac of serous membrane which contains small amount of serous fluid
Lung is enclosed within the pleura
2 different types- visceral and parietal

Question 27

What is the visceral pleura?

Answer 27

> Adheres to the lung, covering each lobe

Question 28

What is the parietal pleura?

Answer 28

> Adheres to inside of the chest wall and upper surface of diaphragm

Question 29

What is the pleural cavity?

Answer 29

> In health, a potential space which is separated by a thin film of serous fluid
This fluid allows pleura to glide over each other which prevent friction during breathing

Question 30

What is normal lung capacity?

Answer 30

> Normal breathing= 15 complete respiratory cycles per min (inspiration, expiration, pause)
Lungs and air spaces never completely empty, this remaining capacity= anatomical dead space (approx 10ml)

Question 31

What is tidal volume?

Answer 31

> Amount of air passing in and out of lungs during each cycle of respiration
Approx 500ml at rest

Question 32

What is inspiratory reserve volume (IRV)?

Answer 32

The extra volume of air that can be inhaled into lungs during maximal inspiration

Question 33

What is expiratory reserve volume (ERV)?

Answer 33

The largest volume of air that can be expelled from the lungs during maximal expiration