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ANAT0001 > The Respiratory System > Flashcards

The Respiratory System Flashcards

1
Q

How does gas exchange take place in small organisms?

A

gas exchange by diffusion across body surface

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2
Q

How does gas exchange take place in more complex/larger organisms?

A

specialised respiratory surface
+ circulatory system
(needed to move gas around: surface of body too small in relation to body volume)

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3
Q

What is a respiratory surface?

A

surface across which oxygen + carbon dioxide are exchanged

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4
Q

What are the ideal properties for a respiratory surface?

A
  • high surface/volume ratio (large resp surface in relation to volume of animal)
  • thin (diffuse gas)
  • wet (dissolve gas: pass through membrane)
  • well supplied in blood
  • in contact with source of oxygen (air, water)
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5
Q

What is the believed ancestral origin of lungs?

A

-fish ancestral to land animals had air bladder that functioned as lung (outgrowth from gut)
-some relatives of these exist today:
ex: lungfish have both gills and lungs
(-problems with gills: vulnerable to damage and water loss)

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6
Q

Where do lungs initially develop in embryo?

A

-lung buds (homolog structure found in lung fish)
=outgrowth from foregut (beginning part of gut)
-in land animals (humans): lungs lie under/ventrally to gut
-lined with endoderm but surrounding support tissues are mesodermal

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7
Q

What are the components of the respiratory tract in humans?

A

Upper Respiratory Tract

  • nasal cavity
  • pharynx

Lower Respiratory Tract

  • larynx
  • trachea
  • main + subsidiary bronchi
  • bronchioles + alveoli
  • associated blood vessels (pulmonary arteries + veins)

Thoracic Walls
-bony thoracic skeleton
-diaphragm
-intercostal muscles
(all 3 used for bringing air in/out of system)
-muscles of arm + abdomen (accessory muscles sometimes used)

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8
Q

What are the composition and function(s) of the ribcage?

A

Composition:
-12 pairs of ribs
-midline sternum
(ribs attached to sternum through costal cartilages

Function:

  • protection of lungs
  • also protection of heart + upper part of abdominal contents (liver, stomach, spleen…)
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9
Q

What are the major divisions of the thoracic cavity?

A

3 major divisions of thoracic cavity:

  • 2 sperate pleural cavities
  • mediastinum: central wall of tissue containing heart + major blood vessels + wrapped in fat membranes = wall (separates pleural cavities)
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10
Q

What is the pleura (of lungs)?

A
  • pleura = double layer of membrane wrapped around each lung
  • inner layer = visceral pleura
  • outer layer = parietal pleura

-both layers in very close contact
=pleural cavity only a potential space (only contains a small amount of fluid - lubrication)
-if air/fluid enters pleural cavity: lung collapses

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11
Q

What is the size of the lung relative to the pleural cavity? Why?

A 
lung is shorter than pleural cavity:
-when quiet breaths/at rest
 = lung doesn't fill pleural cavity
-when deep breath:
 = lung has space to expand into bottom of pleural cavity (diaphragm goes down, lung can fill that space)
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12
Q

What are the differences between the right and left lungs?

A

Right lung:

  • a bit larger: 3 lobes
  • divided by horizontal fissure + oblique fissure

Left lung:

  • smaller: 2 lobes (space needed for heart)
  • only oblique fissure
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13
Q

What is the hilum and what does it comprise?

A

Each lung has a hilum = root where structures enter/leave lung

  • 1 main bronchus
  • autonomic nerves
  • 1 pulmonary artery (deoxygenated blood to lung)
  • 2 pulmonary veins (oxygenated blood away from lung)
  • small blood vessels
  • lymphatic vessels
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14
Q

What forms the loose sleeve allowing lung roots to move up and down during breathing?

A

-hilum is also where visceral and parietal layers become continuous
=loose sleeve
(prevents tearing)

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15
Q

How do the lungs develop?

A

series of branching events:

  • initial lung bud divides in tree-like way to form the bronchi and then smaller bronchioles etc
  • alveoli develop at very end (premature babies have difficulty breathing)
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16
Q

Describe the bronchial tree in each lung

A

Each lung has

  • 1 primary bronchus (division of trachea into each lung)
  • 2 (left) or 3 (right) secondary/lobar bronchi (for each lobe)
  • many smaller bronchi and bronchioles
17
Q

Describe the cartilage in the bronchial tree

A

-cartilage = support
-almost full rings around trachea and primary bronchi
-as bronchi get thinner cartilage more fragmented
(less need for support)
-eventually no cartilage at all in respiratory bronchiole leading up to alveoli

18
Q

What are alveoli and what is their purpose?

A

-alveoli = respiratory surface
-lined with simple squamous epithelium
=thin layer for gas diffusion (CO2 and O2)

19
Q

What is emphysema?

A
  • disease of the lung
  • collapse of small bronchioles and alveoli (become saggy, walls break down)
  • deterioration linked to age but accelerated by smoking/pollution
  • black on outside of lung: tar/soot in lymphatics
20
Q

How does gas exchange occur before birth?

What is the change that occurs at birth?

A

-before birth: gas exchange across placenta
-at birth: abrupt switch to breathing air
=lungs need to be ready for use

21
Q

How long does lung development take?

A
  • 9 months for mature lungs
  • most of lung maturation takes place in last weeks of pregnancy
  • 50-70 million alveoli at birth
  • alveoli continue to form until 8 yrs of age
22
Q

What is surfactant?

A
  • lipoprotein secreted by cells in lungs
  • stops thin-walled alveoli and terminal bronchioles from collapsing/sticking together
  • artificial surfactant often sprayed into lungs of premature babies (have difficulty breathing)
23
Q

In what directions must the thoracic cavity be expanded to draw air into lungs?

A
  • bilaterally
  • superiorly/inferiorly
  • anteroposteriorly
24
Q

Describe inhalation

A
  • breathing in
  • increase in volume = lower pressure
  • ribs move up + out
  • diaphragm flattens
  • arm muscles can be used
25
Q

Describe exhalation

A
  • breathing out
  • decrease in volume = higher pressure
  • ribs fall
  • diaphragm moves up (relaxes back into domed position)
  • abdominal and neck muscles can be used
26
Q

What is the diaphragm made up of?

What nerves innervate it?

A

-diaphragm: skeletal muscle + tendon
-supplied by phrenic nerves:
begin in neck and travel right through thorax to diaphragm
(striated muscle in diaphragm originally from neck mesoderm: then migrates and “drags” nerves with it)
-the only motor supply of diaphragm
-damage to phrenic nerve = can’t breathe

ANAT0001 (12 decks)

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