- Squamous alveolar cells - Organelles clustered around nucleus - Reduced thickness

- Produce surfactant - Reduce alveolar surface tension - Can replicate and produce type 1

Respiration Flashcards by Genn Hector

What are the two zones of the lungs and respiratory system?

Conducting zone and respiratory zone

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What generation is the conducting zone?

Generation 0-16

Trachea –>bronchioles

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What generation is the respiratory zone?

Generation 17-23

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In which zone does gas exchange occur?

Respiratory zone only

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What is the function of the conducting zone?

Conditions incoming air:

Filters
Warms
Humidifies

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Structure of bronchial wall

Cartilage rings
Smooth muscles
Mucous glands
Elastic tissue

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Respiratory epithelium

Ciliated epithelia
Goblet cells
Sensory nerve endings

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Where do the sensory nerve endings lie and what do they do?

Lie underneath tight junctions and detect noxious stimuli

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What do goblet cells do?

Produce musin –> dissolves in fluid layer to form mucuous

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What are bronchioles lined by?

Respiratory epithelium

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What is the air-blood barrier?

A ‘sandwich’ created by flattened cytoplasm of type 1 pneumocytes and the capillary wall

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Type 1 pneumocytes

Squamous alveolar cells
Organelles clustered around nucleus
Reduced thickness

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Type 2 pneumocytes

Produce surfactant
Reduce alveolar surface tension
Can replicate and produce type 1

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Which type of pneuomcytes produce surfactant?

Type 2

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Which muscles are used in quiet inspiration?

Primary muscles of inspiration

- contraction of diaphragm and external intercostal muscles

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Mechanism of quiet inspiration

Thoracic and lung volume increase
Therefore pressure decreases and air moves in down the pressure gradient
- follows Boyle’s law: absolute pressure ∝ 1/volume

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Which muscles are used in forced inspiration?

Primary muscles of inspiration and accessory muscles

involves:
- scalene muscles (move ribcage up)
- sternocleidomastoids (attached to sternum)
- neck/back muscles
- upper respiratory tract muscles

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Quiet expiration mechanism

Passive process using elastic recoil

Relaxation of diaphragm and external intercostal muscles

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What are the primary muscles of expiration?

There are none

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Forced expiration mechanism

Involves; accessory muscles, internal intercostals, abdominal muscles, neck/back muscles

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What is the pleura?

Serous membrane. Pleural cavity between two pleura membranes filled with secretions

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What is the function of the pleura?

Prevents lungs from sticking to chest wall

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What is the pressure of the inter pleural space at rest?

Sub-atmospheric

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What is a pneumothorax?

Collapsed lung due to presence of air in the pleural cavity

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What would happen if inspired during pneumothorax?

Due to inter pleural space equaling atmospheric pressure, elastic nature of lungs would take over and collapse to minimal volume

How would you treat a pneumothorax?

Path the puncture in the membrane and put a chest tube in to allow the lungs to reinflate gradually expelling air from the pleural cavity

What is compliance?

A measure of elasticity in lung | C = ∆V/∆P

What does a low compliance means in terms of ventilation?

More work needed for inspiration

What does a high compliance means in terms of ventilation?

Difficulty expiring - loss of elastic recoil

What are the two components to elastic recoil?

- Elastic nature of cells/ECM | - Recoil due to surface tension generated at air-fluid interface from fluid layer on alveoli

Which equation the relationship between water and air on alveoli surface tension?

Laplace's equation

Are all the air sacs in the lung the same volume?

No, many air sacs of different volumes

What does Laplace's equation show about smaller and larger air sace?

Pressure in larger sacs is lower so air flows from smaller alveoli to larger, collapse

What is Laplace's equation?

P = 2T/r

Role of surfactant lining alveoli

- Reduce surface tension - Prevents alveoli collapsing - Prevents over-inflation

What is the surfactant lining alveoli composed of?

Lipids and proteins, produced by type 2 pneumocytes

What is lung volume measure by? What can't be measured by this?

Spirometer | Residual lung volume cannot be measure

What are the two types of dead space?

Anatomical: volume of conducting zone Physiological: volume of lung not participating in gas exchange

What is tidal volume?

Normal volume of air displaced during normal inspiration and normal expiration

What is FEV1?

The volume of air displaced in a forced expiration in one second

What is the inspiration capacity?

The total volume of air that can be inspired after normal expiration

What is the expiration reserve volume?

The additional amount of air that can expelled after a normal exhalation

What is the residual volume?

The amount of air that is left after expiratory reserve volume is exhaled

What is vital capacity?

The maximum volume of air that can be inhaled or exhaled during a respiratory cycle IC + ERV

Using lung volumes, what can be a good health indicator?

FEV1/VC

Which technique is used to measure functional residual capacity?

Helium dilution technique

Lung volumes during exercise

- Tidal volume increases - Reserve volumes decreases - TLC and RV remain the same

Two factors that affect the airflow in the lung

- Difference of pressure - Resistance V = ∆P/R

Which law is the impact of resistance on flow determined by?

Poiseuille's Law: Airway resistance is proportional to gas viscosity and the length of the tube but is inversely proportional to the fourth power of the radius

What is the airway resistance inversely proportional to?

The fourth power of the radius

Factors affecting resistance

- Airway diameter - Mucous secretion - Oedema - Airway collapse

Control of bronchial smooth muscle: Constriction | ANS and humoral factor

Parasympathetic - ACh released from vagus and acts on muscarinic receptors (humoral factor) histamine - released during inflammatory response

Control of bronchial smooth muscle: Dilation | ANS and humoral factor

Sympathetic - Norepineprine released - weak agonist | (humoEral factor) Epinephrine - better agonist

Is the inter pleural pressure greater at the apex or the base?

The apex

What is Dalton's law?

The total pressure of a mixture of gases is the sum of their individual partial pressures

Which law is used for gases in solution?

Henry's Law

What kind of structure does haemoglobin have?

Tetrametric structure with a mW of 68kD Haem unit and global chain 2 alpha and 2 beta chains

What chains are in children's haemoglobin?

2 alpha and 2 gamma chains

What is the haem unit in haemoglobin?

Porphyrin rin containing single iron atom

Which enzyme converts Fe3+ ---> Fe2+?

Methaemoglobin reductase

What two states does haemoglobin exist in? What are their affinities for O2?

Tense - Low affinity for O2 | Relaxed - High affinity for O2

Haemoglobin dissociation curve: Temperature

Increase - shifts curve right | Decrease -shifts curve left

Haemoglobin dissociation curve: pH

Increase - shifts curve left | Decrease - shifts curve right

What is the Bohr shift?

Shift in dissociation curve caused by pH

What binds with a higher affinity to haemoglobin?

2, 3-diphosphoglycerate

What occurs in tissues undergoing respiration which shifts the dissociation curve right?

- Increased temperature - Increased CO2 production - Increased production of 2, 3-DPG - Decrease in pH

What replaces the ß-globin chains in foetal haemoglobin?

Gamma chains (these aren't sensitive to 2, 3-DPG)

Which has a higher affinity for oxygen: haemoglobin of foetal haemoglobin?

Foetal haemoglobin - curve is leftwards or normal Hb

How does the blood carry CO2?

- Dissolved CO2 - Carbonic acid - Bicarbonate ions - Carbonate ions - Carbamino compounds

How and where is CO2 converted to carbonic acid?

Carbonic anhydrase in lungs

Respiration Flashcards

(70 cards)