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Human Anatomy Semester 2 > The Respiratory System > Flashcards

The Respiratory System Flashcards

1
Q

Describe the structure of the nostrils and nasal passages

A

Vibrissae - Small hairs in the nares which filter particles

Septum - Partition which separates the 2 nasal passages

Conchae - Ridges of cartilage of the posterior wall of the nasal passages, warm air and increase SA of the cavity

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2
Q

How many sinuses are there in the nose, where are they located and what is their function?

A

4 Paranasal sinuses in the frontal, sphenoid and maxillary bone - Moisten and warm air and provide speech resonance

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3
Q

What are Choanae?

A

Pair of posteiror openings in the nasal cavity which allow for the passage of air into the nasopharynx

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4
Q

What is the function of the nasopharynx?

A

Acts as a conduit for air, closing during swallowing

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5
Q

What is the epiglottis?

A

Consists of elastic cartilage, forming a free flap to prevent food from entering airways

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6
Q

Describe the structure and function of the trachea

A

Consists of the mucosa, submucosa and adventitia

15-20x C-shaped rings of cartilage reinforce and protect the trachea.

Divides into 2 to form the bronchi

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7
Q

Describe the structure of the lungs

A

Divides into secondary/tertiary bronchi, bronchioles and terminal bronchioles, which terminate at the alveoli

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8
Q

Describe the structure and function of the bronchi

A

Supply air to the lungs - The right mainstem bronchus is shorter, wider and more vertical than the left

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9
Q

What are alveoli?

A

Air sacs where gas exchange takes place, found at the end of alveoli ducts

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10
Q

What is the function of the conducting zone?

A

Warms incoming air to body temperature to optimise enzyme reactions

Moistens air to 100% humidity to protect the alveoli

Filters out harmful particles or microorganisms that may be in the inhaled air.

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11
Q

True or false, does gas exchange occur in the conducting zone?

A

False, only serves the provide optimal conditions for gas exchange in the alveoli

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12
Q

What organs are found in the respiratory zone?

A

Respiratory bronchioles

Alveoli

Blood capillaries

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13
Q

Describe the structure of the respiratory zone

A

Epithelial lining changes to simple cuboidal cells without goblet cells

Tube walls become very thin - respiratory bronchioles

Cilia are still present to sweep away mucus

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14
Q

How many alveoli are in the lungs and how much surface area do they provide?

A

300 million, giving a surface area off 27 square meters

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15
Q

Describe the structure and function of the alveolar sacs

A

Epithelium (simple squamous)

Type II cells which produce an oily secretion called surfactant (lowers surface tension of alveolar fluid)

Macrophages to remove debris or microorganisms

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16
Q

Why is the surfactant found in alveolar sacs important?

A

Alveoli must be moist for gas exchange and this water creates a strong surface tension which could collapse the lungs.

Surfactant contains lipoproteins which reduce the surface tension from 20-30mmHg to 4mmHg

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17
Q

How is the respiratory system provided with blood?

A

The pulmonary artery supplies deoxygenated blood

Bronchial arteries from the thoracic aorta supply oxygenated blood to lung tissue

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18
Q

Describe the structure of the lungs

A

Cone-shaped structures in the right and left pleural cavities

Right lung contains 3 lobes, being shorter, broader and larger than the left lung

Left lung contains 2 lobes

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19
Q

What allows the lungs to expand with incoming air and recoil when expelling air?

A

Elastic connective tissues in the stroma of the lungs

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20
Q

Define the structure and function of the pleura and pleural cavities

A

Pleura - Double sided membrane enclosing the lung

Pleural cavity - Tiny area fluid-filled between double layers

Functions

Lubricates the pleural surfaces

Creates a bond between the layers, causing the lungs to move with the chest wall during breathing

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21
Q

Define pulmonary ventilation

A

Production of differences in total pressure between interior (alveolar pressure) and exterior (atmospheric pressure) in the respiratory zone

22
Q

What is Boyle’s Law?

A

At a constant temperature the pressure of a given quantity of gas is inversely proportional to its volume

23
Q

Describe the structure of the diaphragm

A

Arises from the lateral and posterior walls of the body cavity, forming a large dome shaped muscle upon which the lungs rest

24
Q

How do muscles contract and relax during inspiration and expiration

A

Inspiration - Contractions of the diaphragm and intercostal muscles contract increase thoracic volume (active)

Expiration - Muscles associated with inspiration relax with the elastic properties of the lungs allowing for a return to resting volume (Relatively passive)

25
Q

What are the two types of pulmonary disorders?

A

Restrictive - Total volume of air the the lungs can hold is decreased (Scar tissue restricts expansion)

Obstructive - Difficult to exhale all air out of lungs (asthma)

26
Q

What is Forced expiratory volume in 1s (FEV1)

A

Volume exhaled in the first second after deep inspiration and forced expiration

27
Q

What is forced vital capacity (FVC)

A

Total volume of air that the patient can forcibly exhale in one breath

28
Q

How is the FEV1/FVC ratio used in diagnosis?

A

An obstructive spirometry pattern will see less than 80 percent of the predicted normal FEV1 and FVC will decrease but to a lower extent (longer time to reach the same vol as a normal patient)

A restrictive spirometry pattern will have a lower volume, plateauing at around the same time as a normal patient (both FEV1 and FVC will be around 80% of the predicted values)

29
Q

Describe the respiratory surface of the alveolus

A

Made up of alveoli and capillary walls, which share the same membrane allowing for a short diffusion path that is only 1 cell thick

30
Q

What is external respiration

A

Exchange of oxyge and carbon dioxide between alveoli and pulmonary capillary blood

31
Q

What is internal respiration

A

Exchange of oxygen and carbon dioxide between the tissues of the body and the blood

32
Q

What is partial pressure and how is it calculated?

A

The pressure that a given gas in a mixture contributes to the total pressure inside the container or in the atmostphere

Partial pressure = % of particular gas x atmospheric pressure

33
Q

What is the gradient bbetween alveoli and capillaries?

A

Alveolar PO2 = 100mmHg
Blood PO2 = 40mmHg

Driving external respiration across the alveolar membrane along the length of the pulmonary capillary until the partial pressure = 105mmHg

34
Q

What is henry’s law?

A

Equilibrium is determined by partial pressure of the gas and its solubility in liquid

Solubilised gas = partial pressure of gas x solubility coefficient

35
Q

How do solubility coefficients differ between oxygen and carbon dioxide?

A

O2 = 0.024
CO2 = 0.57

CO2 is 20x more soluble in water than O2

36
Q

Describe the CO2 diffusion gradient

A

Even with a much smaller CO2 gradient, equivalent CO2 diffuses from the blood to the alveoli, causing a higher solubility of plasma CO2

37
Q

What 4 factors affect gas diffusion across respiratory membranes?

A

The thickness of the membrane

The diffusion coefficient

The surface area

The partial pressure difference of gases across the membrane (PO2 high in alveoli and PCO2 high in capillaries = net diffusion of O2 into blood and CO2 into alveoli)

38
Q

How much new oxygen is needed in the bloodstream to support internal respiration?

A

250ml/min

39
Q

Why is haemoglobin needed?

A

O2 is poorly soluble in blood with only 15ml/min of O2 reaching tissues when dissolved in blood

40
Q

Describe erthrocytes

A

700x more numerous than white blood cells

7um wide, donut shaped with a central depression

This size and shape maximises the surface area

1/3 of each erythrocyte’s mass comes from haemoglobin

41
Q

Describe haemoglobin

A

Binds oxygen in alveoli capillaries

Each molecule contains 4 polypeptides (globins) which bind a heme molecule which subsequently binds an iron molecule allowing for loading of O2

Roughly 300 million Hb per erthrocyte

42
Q

Describe oxygen association in haemoglobin

A

When O2 binds to haemoglobin, the 3 other binding sites’ affinity for O2 increases, the reverse is true for unloading

43
Q

Describe the right and left Bohr shift

A

Left shift (increased affinity):
Decreased temp
Decreased 2-3DPG
Decreased [H+]
Carbon monoxide formed
Oxyhaemoglobin releases less O2

Right shift (increased affinity):
Increased temp
Increased 2-3 DPG
Increased [H+]
Oxyhaemoglobin releases more O2

44
Q

What are the 3 forms that CO2 is carried in the blood?

A
  1. Dissolved (7-10%_
  2. Attached to Hb (20-23%)
  3. Converted to bicarbonate ions (only found in erthrocytes)(70%)
45
Q

How is carbonic acid formed?

A

Reversibly formed when CO2 dissolves in the blood however this is a slow process so the enzyme carbonic anhydrase speeds up this reaction

46
Q

How is bicarbonate transported in erythrocytes?

A

Carbonic acid is unstabble and readily dissociates into H+ and bicarbonate (HCO3-), providing buffering for the blood

47
Q

What parts of the brain control respiration

A

The medulla oblongata and the pons (brain stem)

48
Q

Describe the dorsal root group (DRG)

A

Mostly inspiratory movements.

Normal breathing is generated by neurons stimulating both phrenic and intercostal nerves

49
Q

Describe the pneumotaxic area

A

Promotes passive and active inhalation

Inhibits inspiration and apneustic centre

50
Q

Describe the apneustic area

A

Excites the medullary inspiratory centre, increasing the depth of inspiration and inhibits the expiratory centre

51
Q

What part of the brain allows for voluntary control of breathing?

A

The cerebral cortex - allows the involuntary respiration to be overridden

52
Q

What stimuli influence the respiratory centre control

A

Central chemoreceptors - detect a decrease in pH, increasing inspiration

Peripheral chemoreceptors in carotid bodies - detect an increase pH or decrease in arterial pressure of oxygen

Stretch receptors in the walls of bronchi and bronchioles - activated when lungs expand to their physical limit

Human Anatomy Semester 2 (3 decks)

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