Senario Four - The Respiratory Tract

Question 1

what separates the lungs?

Answer 1

heart and the mediastinum

Question 2

what are the surfaces of the lungs?

Answer 2

costal surface - contact with ribs

mediastinal surface - centrally

Question 3

what is present on the mediastinal surface of the lung?

Answer 3

the hilum (or ROOT) - bronchi, blood vessels, lymphatics and nerves - held together by pleura and CT

cardiac notch on (L) side - due to apex of the heart

Question 4

Name the lung lobes and the fissures dividing them

Answer 4

right lung: superior lobe - horizontal fissure, middle lobe - horizontal and oblique fissures, inferior lobe - oblique fissure

Left lung: superior lobe and inferior lobe divided by single oblique fissure

Question 5

what is a bronchopulmonary segment

Answer 5

further division of the lungs to form:
10 segments on the right
9 on the left

each supplied by their own tertiary bronchi

Question 6

what is a lobule?

Answer 6

a division of a bronchopulmonary segment supplied by
1x lymphatic vessel, 1x arteriole, 1x venue and 1x nerve
wrapped in connective tissue.

Question 7

Describe the function of the nose

Answer 7

warm, moisten and filter incoming air
detect olfactory stimuli
modifying speech vibrations

Question 8

describe the structure of the nose

Answer 8

bony and hyaline cartilage framework - to keep it patent

inferior respiratory region - lined with ciliated psuedostratified columnar epithelium & lots of goblet cells

Anterior vestibule - coarse hairs to filter out large particles

Question 9

what is the purpose of the inferior respiratory region of the nose?

Answer 9

goblet cells produce mucus which traps debris

ciliated psuedostratified columnar epithelium waft trapped particles down to the pharynx - to be spit out or swallowed.

Question 10

what is the structure of the pharynx?

Answer 10

from the internal nares to the level of the cricoid cartiliage

nasopharynx - ciliated psuedostratified columnar epithelium
oropharynx and laryngopharanx - non-keratinised stratified columnar epithelium

funnel shaped 13cm tube

skeletal muscle lined with mucous membranes

Question 11

what is the function of the pharynx

Answer 11

passageway for air and food
resonating chamber for speech sounds
tonsils for immunological reactions against foreign invaders

Question 12

what is the structure of the larynx

Answer 12

short passageway between laryngopharynx and the trachea

supported by 9 pieces of cartiliges

coated in non-keratinised stratified squamous epithelium superior to vocal cords

ciliated psuedostratified columnar epithelia inferior to vocal cords - with goblet cells and basal cells

Question 13

what is the structure and function of the epiglottis?

Answer 13

leaf shaped elastic cartilage - coated in epithelium

when pharynx and larynx rise, epiglottis moves down to form lid over glottis - blocking entry to the trachea and vocal cords

Question 14

what is the function of the larynx

Answer 14

conducting pathway for food and air

Question 15

what are the 9 cartilages of the larynx?

Answer 15

thyroid
epiglottis
cricoid

2x arytenoid
2x cuneiform
2x corniculate

Question 16

Describe the shape and location of the trachea?

Answer 16

12cm long
2.5 cm wide
anterior to oesophagus

from larynx to T5 before divides into L and R bronchi

Question 17

what are the 4 layers of the trachea, and their structure?

Answer 17

mucosa - internal layer of ciliated psuedostratified columnar epithelium, with underlying lamina proprietary (elastic and reticular tissues)

submucosa - areolar connective tissue containing seromucosa glands

hyaline cartilage - 16-20 C shaped rings - deficient posteriorly
- coated in fibromuscular membrane - with SM & elastic tissue

adventitia - areolar CT - joins trachea to surrounding tissues

Question 18

what is the function of the mucosa?

Answer 18

protects against dust

Question 19

what is the function of the submucosa?

Answer 19

produce mucus

Question 20

what is the function of the hyaline cartilage?

Answer 20

SM contraction to adjust trachea diameter
provide semi-rigid support
allow the passage of food down oesophagus

Question 21

what is the function of the adventitia?

Answer 21

joins trachea to surrounding tissues

Question 22

what is the structure of the main, lobar and segmental bronchi?

Answer 22

ciliated psuedostratified columnar epithelium

main bronchi - C shaped cartilage
lobar and segmental bronchi - plates of cartilage to maintain patency

Question 23

what is the pathway of the main bronchi?

Answer 23

divide into L and R from trachea at T5 - at the point of the carina

R bronchi is more vertical, shorter and wider than L - more likely to aspirate

Question 24

what is the carina

Answer 24

area of division between L and R bronchi - highly sensitive - initiates the cough reflex

Question 25

what is the pathway of the lobar bronchi?

Answer 25

when the main bronchi enter the lungs - divide into: (R) - superior, middle and inferior lobar bronchi (L) - superior and inferior lobar bronchi

Question 26

what is the pathway of the segmental bronchi?

Answer 26

divisions of the lobar bronchi to supply the bronchopulmonary segments - 10 on R, 9 on L

Question 27

what is the structure of the large bronchioles?

Answer 27

simple, ciliated columnar epithelium - contain goblet cells - contain more SM than bronchi

Question 28

what is the structure of the small bronchioles?

Answer 28

simple, ciliated columnar epithelium - contain NO goblet cells - contain more SM than large bronchioles

Question 29

what is the structure of the terminal bronchioles?

Answer 29

non-ciliated columnar epithelium large amounts of SM contain Clara - club cells

Question 30

what is a clara cell

Answer 30

protects against inhaled carcinogens produce surfactant act as stem cells to produce epithelia

Question 31

what is the pattern of structural changes throughout the conducting system?

Answer 31

ciliated psuedostratified columnar epithelium in main lobar and segmental bronchi --> simple, ciliated columnar with goblet cells in large bronchioles --> no goblet cells in small bronchioles --> non-ciliated simple columnar in terminal bronchioles large amounts of cartilage decreases down conducting pathway - no cartilage in terminal bronchi as cartilage decreases, smooth muscle increases

Question 32

what is the role of the smooth muscle in the conducting pathway

Answer 32

forms a spiral band to maintain patency | - lack of cartilage can mean in asthma the SM spams can close off airways

Question 33

what are the 5 defense mechanisms for the respiratory tract?

Answer 33

``` cough sneeze MCE wandering macrophages antiproteases ```

Question 34

what is the effect of the sympathetic nervous system on the conducting system

Answer 34

fight or flight respose during exercise cause release of A and NA to relax SM

Question 35

what is the effect of parasympathetic input to the conducting system?

Answer 35

release of histamine during allergic reactions | causes SM constriction

Question 36

where does the conducting system end and the gas exchange system starts

Answer 36

ends at terminal bronchioles starts in the respiratory bronchioles --> alveolar ducts --> alveoli

Question 37

where is the MCE

Answer 37

all non-gas exchange surfaces facilitated by ciliated cells From terminal bronchioles to the larynx

Question 38

what does the MCE do

Answer 38

Moves particles which have been trapped in mucous towards the mouth by wafting of cilia once in the mouth either coughed out or swallowed and destroyed by stomach acid

Question 39

how much mucous is produced daily?

Answer 39

20-30ml

Question 40

what is the mucous blanket?

Answer 40

a layer in which the cilia project into has two layers: - sol layer - watery component to allow cilia wafting - gel layer - sticky layer to trap particles

Question 41

where does most wafting occur?

Answer 41

in the sol layer of the mucous blanket

Question 42

where is the mucous of the gel layer produced?

Answer 42

goblet cells and mucous cells

Question 43

what are the 6 parts of a reflex arc?

Answer 43

receptors, afferent, CNS, efferent, effector, action

Question 44

what are the receptors in the cough reflex

Answer 44

larynx, carina, pleura, pericardium, diaphragm and auditory canal respond to irritants in the respiratory tract or when mucous production is too high

Question 45

what is the afferent to the cough reflex?

Answer 45

the vagus nerve

Question 46

where does the CNS respond to cough reflex?

Answer 46

modulated in the cortex & cough centre in medulla oblangata

Question 47

what is the efferents and effectors to the cough reflex?

Answer 47

1) vagus to superior largengeal nerve - laryngeal adductors 2) phrenic nerve - C3, 4, 5 - diaphragm 3) spinal motor nerves - T1- T11 - internal and external intercostals & T6-T12 - abdominals (oblique and rectus abdominus)

Question 48

what is the action of the cough reflex?

Answer 48

laryngeal adductors - glottic closure diaphragm and external intercostals - deep inspiration internal intercostals and abs - forced expiration

Question 49

what are the 4 stages to the cough sequence?

Answer 49

1. deep inspiration (near total lung capacity) 2. glottic closure 3. isometric contraction of abdominals - - glottis remains closed and increase in intraabdominal pressure 4. sudden opening of glottis - explosive expiration - - creates shearing forces (>100mph) - - unsticks secretion from airways

Question 50

describe the structure of the respiratory bronchioles

Answer 50

microscopic subdivision of terminal bronchiole simple cuboidal cells changing to simple squamous cells further down no cilia and no goblet cells

Question 51

describe the function of respiratory bronchioles

Answer 51

begin the respiratory zone alveoli bud from the walls gas exchange surface

Question 52

describe the structure of the alveolar duct?

Answer 52

subdivisions of the respiratory bronchioles - with a terminal dilation of the alveolar sac simple squamous epithelium

Question 53

function of the alveolar duct?

Answer 53

gas exchange surface - passage way for air | produce surfactant

Question 54

describe the structure of an alveolar sac?

Answer 54

the terminal dilation of the alveolar duct forms outpouchings - the alveoli simple squamous epithelium

Question 55

function of the alveolar sac

Answer 55

gas exchange, passage way for air and surfactant production