The Respiratory System

Question 1

How much pulmonary vasculature makes up the lungs weight?

Answer 1

Pulmonary vasculature = 500ml blood = 40% lung weight

Question 2

Describe what happens during inhalation?

Answer 2

Diaphragm contracts = moves down, increasing volume of thoracic cavity = pressure inside decreases, air moves from an area of higher pressure, the atmosphere, to an area of lower pressure, the lungs

Question 3

What happens during exhalation?

Answer 3

diaphragm relaxes, moves up = reduces volume of thoracic cavity = intrapulmonary pressure increases = Air flows out of Lungs to lower atmospheric pressure

Question 4

Where is odour detected?

Answer 4

Olfactory region –> thick pseudostratified columnar epithelium, dendrite + non-motile cilia detect odour – no goblet cells

Question 5

What are the secretion in the trachea and bronchi?

Answer 5

mucins, water, serum proteins, lysozyme (destroys bacteria), antiproteases (inactivate bacterial enzymes)

Question 6

Describe the nasal non-olfactory region

Answer 6

Non-olfactory region –> pseudostratified ciliated epithelium, mucous glands, venous plexus swells alternating nostril airflow

Question 7

Outline the structures in the larynx

Answer 7

Larynx = true vocal cord – open close many times, ventricles contribute to resonance of voice. Vocal cord (help stop foreign objects) = vocal ligament + vocalis muscle

Question 8

Describe the trachea

Answer 8

ridged, C shaped rings to keep it open – transform to bone with ageing. Submucosa thicker in COPD = small lumen

Question 9

What is structurally different between the trachea and bronchi?

Answer 9

trachea = C shaped rings, bronchi = rings completely encircle lumen

Question 10

When is the respiratory system intrapulmonary?

Answer 10

secondary bronchi

Question 11

Describe the bronchioles

Answer 11

Bronchioles = blood supply pulmonary arteries (deoxygenated) pulmonary vein (oxygenated) – NO CARTILAGE (allows constriction = bronchoconstriction), contracts in asthma. Clara cells = secrete surfactant lipoprotein stop walls sticking together.

Question 12

Name the smallest airway and its key feature

Answer 12

Terminal bronchioles = smallest airway, no goblet cells – stop drowning in mucus

Question 13

Where are the mucous membranes present

Answer 13

Conducting zone = MUCOUS MEMBRANE

Question 14

The pleural sacs are what type of membrane

Answer 14

Serous membrane

Question 15

What is the respiratory zone?

Answer 15

Respiratory zone = gas exchange – abundant capillaries – respiratory bronc. bronchioles, alveolar ducts, alveolar sacs, alveoli

Question 16

Describe the alveoli and the cells types present

Answer 16

90% cover by type I pneumocytes (squamous), 10% type II pneumocytes (cuboidal) secrete surfactant, devel until 8yrs, 300 million, surrounded by basketwork of elastin/capillaries/reticular fibres, air as close as 0.2μm from blood

Question 17

How does hyperventilating lead to fainting?

Answer 17

Drop in CO2 due to hyperventilating = hypocapnia – low CO2 = less carbonic acid = blood pH rises (low pH = changes shape Hb, high pH = vasoconstriction) not enough blood to the brain = faint

Question 18

Why does oxygen dissociate from haemoglobin?

Answer 18

Active tissue burns through oxygen – low partial pressure = oxyhaemoglobin loses oxygen from plasma to tissue. Other triggers = heat (changes Hb shape), CO2 (binds Hb, changing shape + makes blood more acidic H+ bind) – activate the release of oxygen = lower Hb affinity for oxygen

Question 19

What is the Haldane effect?

Answer 19

Deoxygenated blood can carry increasing amounts of CO2, whereas oxygenated blood has a reduced CO2 capacity.

Question 20

What is the Bohr Effect?

Answer 20

haemoglobin’s oxygen binding affinity is inversely related both to acidity and conc of CO2

Question 21

How can someone get a hoarse voice?

Answer 21

Hoarse voice = impinging on left recurrent laryngeal nerve – loops under aorta (can be caused by aortic aneurism)

Question 22

In regards to respiratory anatomy how can wasting in the lower arm be caused?

Answer 22

Muscle wasting lower arm = cancer in lung apex impinges brachial plexus

Question 23

What causes paralysis on one side of the diaphragm?

Answer 23

tumour impinges left/right phrenic nerve = ipsilateral elevation

Question 24

Describe COPD

Answer 24

Caused by smoking or alpha 1-antitrypsin def: Goblet cell hyperplasia, smaller proportion of ciliated cells, hypertrophy of submucous glands = more mucus and fewer cilia to move mucus

Question 25

Outline emphysema

Answer 25

Destruction of alveolar walls and permanent enlargement of air spaces which can result from smoking or alpha 1-antitrypsin deficiency. Alveolar walls normally hold bronchioles open. Damage = collapse = difficult for lungs to empty = air trapped in alveoli. Pursed lip breathing. Damage = loss of elastin = chest springs out = barrel chest

Question 26

What is pneumonia?

Answer 26

Inflammation of the lung caused by bacteria, lung consolidates (filled with liquid) as the alveoli fill with inflammatory cells. Streptococcus pneumoniae

Question 27

Name the 2 pleura and where they are found

Answer 27

Parietal pleura –> lines the chest wall. Visceral pleura –> cover lung

Question 28

How does surface tension work?

Answer 28

Water molecule, +ve and –ve ends attract each other – H bonds. At surface - water molecules don’t have any charges pulling on them from above = able to get more densely packed = stronger intramolecular force = surface tension

Question 29

What is the pleural fluid?

Answer 29

separates and lubricates 2 membranes, provides surface tension to prevent the lung from collapsing. -ve pressure keeps pleurae together = lung expands

Question 30

What are the pleural fluids –ve pressures?

Answer 30

Inspiration = -8cmH2O (below atmosphere) Exhalation -4cmH2O (below atmosphere)

Question 31

What is boyles law?

Answer 31

When the volume of a container increases, the pressure decreases. When the volume of a container decreases, the pressure increases

Question 32

Outline LaPlaces Law

Answer 32

If two areas of different pressure communicate, gas will move from area of higher pressure to area of lower pressure

Question 33

What can the pleural space be incorrectly filled with?

Answer 33

Air –> pneumothorax. Blood –> haemothorax. Pus –> empyema. Watery transudate or exudate –> pleural effusion

Question 34

What is the role of surfactant?

Answer 34

surface tension wants to collapse the alveoli, surfactant hydrophilic heads interfere with H bond = decreases surface tension = less chance of alveoli collapse

Question 35

List the order of the respiratory system

Answer 35

Nasal cavity, pharynx, larynx, trachea, primary right/left bronchi, secondary bronchi, bronchioles, terminal bronchioles, respiratory bronchioles, alveolar ducts, alveolar sacs, alveoli.

Question 36

What are Clara cells?

Answer 36

Found in bronchioles, secrete surfactant lipoprotein stop walls sticking together, CC16 lower = lung damage, higher = leaking across air-blood barrier

Question 37

What is alpha 1-antitrypsin?

Answer 37

It protects tissues from enzymes of inflammatory cells especially neutrophil elastase. In its absence (such as in alpha 1-antitrypsin deficiency), neutrophil elastase is free to break down elastin, which contributes to elasticity of lungs = emphysema or COPD