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Physiology of Organisms > 18-20 > Flashcards

18-20 Flashcards

1
Q

What is physiologic dead space?

A

the sum of anatomic and alveolar dead space

  • anatomic = air left in conducting airways
  • alveolar = alveoli with no blood flow
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2
Q

What is gill dead space?

A

the water that flows through gills but not between lamellae consitutes anatomic dead space
- Lamellae dead space is if water passes between and then no exchange of gases

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3
Q

What is the expired minute volume?

A

volume of air moved out of the lungs in a minute

Ve = Vt x Breathing Frequency

  • based on assumption that the volume inspired is equal to the volume expired
  • not quite true
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4
Q

The volume of fresh air that actually reaches alveoli is the alveolar ventilation

A

Va = (Vt - Vd) x f

  • Vt is the tidal volume
  • Vd is the dead space volume
  • f is breathing frequency
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5
Q

How can the alveolar ventilation be measured directly?

A 
- volume of expired CO2/fractional concentration of CO2 in the alveolar gas
x K (to account for BTPS and STPD conversion)

K usually = 0.865

= alveolar ventilation equation

VeCo2 from spirometer measurements

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6
Q

What happens during hyperventilation?

doubling alveolar ventilation

A

arterial Pco2 reduces (halves)
- P02 must increase
Palveolar O2 increases but not double

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7
Q

What happens during hypoventilation? halving of alveolar ventilation

A

double arterial Pco2

  • alveolar P02 must decrease
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8
Q

What is the respiratory exchange ratio?

A

R = volume CO2 exhaled/ volume of O2 taken up

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9
Q

What is the alveolar gas equation?

- work out alveolar oxygen partial pressure

A

PICTURE OF EQUATION

- pg 18

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10
Q

Where is the central pattern generator of breathing in the brain?

A

brain stem

  • both frequency and tidal volume alteration
  • probably the medulla
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11
Q

What is the negative feedback system if differs from 40mmHg PCO2 or 100mmHg PO2?

A

detected by sensors

  • fed to controller
  • superimposed on regular cyclic pattern
  • arterial O2 conc is achieved by regulating arterial blood CO2 content
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12
Q

What happens when CO2 dissolved in blood?

A

How to get HCO3- ions

  • react with water to get carbonic acid which dissociates
  • reaction to carbonic acid by carbonic anhydrase
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13
Q

How is CO2 level measured in blood?

A

Proton content (pH)
- chemoreceptive cells
Carotid and aortic
- outside of brain

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14
Q

What are the chemosensitive cells of the carotid body?

A

glomus cells
- same in aorta

  • inhibition of potassium channel activity with increase H+
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15
Q

Formula for calculating partial pressure

A

P = fraction of mixture occupied by gas x total pressure exerted by mixture

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16
Q

how to calculate the partial pressure of gas in a liquid

A

Pgas = [conc]/Solubility coefficient of gas

17
Q

How to calculate the concentration of oxygen at the surface in fractions of an atmosphere?

A

FO2 = (VO2 x r^2)/6K

  • VO2 = rate of oxygen consumption as cm3 of oxygen per cm3 tissue per minute
  • r = radius of sphere in centimetres
  • K = diffusion constant in cm2 per atmosphere per minute
18
Q

What is the respiratory organ of insects?

A

Tracheal system

- exploits fact that oxygen and carbon dioxides diffuse 10,000 faster in air than in water

19
Q

Structure of tracheal system

A 
Spiracle
Trachea
Tracheoles
- air filled tubes
- access to all cells
- At various intervals - small air sacs - increase tracheal volume and so oxygen storage capacity
20
Q

How can insect tracheal system in water work ->

A

Diffusion gill

  • Notonecta
  • Have bubbles

Attached to the ventral surface of the abdomen
- basically the same pressure as atmospheric pressure as doesnt dive very deep

  • 6 hours
  • though dependent
    1. Insect metabolic rate
    2. Initial size of bubble
    3. Depth at which bubble taken
21
Q

Way to stabilise bubble?

A

Plastrons

  • hairs = hydrophobic
  • not like diffusion gill
22
Q

Comparison as air and water - respiratory medium

A
  1. O2 concentration
    - 1:30 ratio water-air
  2. Viscosity
    - 50:1
  3. Heat Capacity
    - 3000:1
  4. Diffusion coefficient
    - 1:300,000
23
Q

How have the lungs and gills evolved for gas exchange?

A
  1. maximise gas exchange
  2. minimise work associated with it
  • as evolved in air and water respectively - different ways of doing that
24
Q

Structure of the lung

A

DIAGRAM

  • airway branches
  • narrower, shorter and more numerous

CONDUCTING ZONE = first 17 generations

  1. Warm and humidify air
  2. Distribute air to the depths of the lungs
  3. Defence against bacteria and dust

Trachea —> bronchi —>lobar bronchi —> segmental bronchi —>all the way till the terminal bronchioles
- no exchange in this region —>anatomic dead space

First 4 = U shaped cartilage
then plates before disappearing

25
Q

Alveoli

A

gas-exchange units of lungs

  • denote respiratory zone
  • 2.5-3 litres

Flow in by bulk flow
- down pressure gradient

26
Q

Structure of the gill

A

DIAGRAM

  • 4 major gill arches
  • each gill arch has 2 rows of gill filaments
  • lamellae
  • juxtaposed so like a sieve
  • push water through = slow down
27
Q

How to calculate net flux

A

Net flux = (Conc before-conc after) x (Area/thickness) x D
- D is diffusion coefficient

  • diffusion across a sheet
28
Q

Lung circulation

A
  • capillary bed alongside branched- splits when it does
  • highly convoluted
  • lower pressure so less fluid out into interstitial fluid

ALL of cardiac output goes through so gas exchange occurs every time blood circulated through body

29
Q

Gill circulation

A

COUNTER-CURRENT

  • blood and water in opposite direction
  • maintain a conc gradient
  • as no equilibrium point reached
30
Q

Calculate flow

A

Flow = ΔPressure/resistance

31
Q

How are the lungs placed within the chest cavity?

A
  • airtight thoracic cavity
  • separated from abdomen by diaphragm
  • 12 pairs of ribs
  • sternum
  • internal and external intercostal muscles
  • Thin visceral pleura encases lungs
  • separated from the parietal viscera lining on inside of thoracic cage by
  • FLUID = 10μm
32
Q

How do the lungs return to size during expiration

- passive

A
  • elastic recoil of chest wall
  • inward elastic recoil of lungs
  • intrapleural pressure = very small
  • ensures stays together
33
Q

Ventilating the gills

A

GRAPH
- Teleost fish
(cartilaginous fish have to keep swimming to breathe)

34
Q

Volumes of the lungs

A

DIAGRAM

35
Q

Gas equation

A

pv = nRT

36
Q

estimate for VSTPD

A

VSTPD = VATPS x 0.9

VBTPS = VATPS x 1.09

VSTPD = volume at standard temperature and pressure dry

VATPS = volume at atmosphere temperature and pressure saturated

VBTPS = volume at body temperature and pressure saturated

Physiology of Organisms (9 decks)

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