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Physiology > Respiratory Physiology > Flashcards

Respiratory Physiology Flashcards

1
Q

what does the respiratory system do?

A
  1. oxygen into the blood to create ATP in mitocondria (electron transport chain)
  2. removes carbon dioxide from blood
  3. regulates blood pH
  4. speech
  5. microbial defense
  6. chemical messenger concentrations
  7. traps and dissolves small blood clots
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2
Q

conducting zone

A

trachea

primary bronchi

smaller bronchi

terminal bronchioles

functions:

cilia move mucus coordinatedly out of the lung toward the mouth

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3
Q

respiratory zone

A

alveolus is wrapped by capillaries

blood gas barrier between alveolus and capillary is 2 cells thick and very thin

type 1 cells, very thin

type 2 cells, produces surfactant

alveolar macrophage, immune cells, move around and picks up foreign particles

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4
Q

alveolar ventilation

A

pulmonary ventilation (VE) = volume of one breath (tidal volume VT) x breaths per min (respiratory rate RR)

conducting zone (amount of air that doesn’t participate in gas exchange anatomical dead zone VD) - every pound ~ 1 mL x RR

alveolar ventilation (VA)

VA = VE - VD

= (VT x RR) - (bodyweight x RR)

slower and deeper breaths - more air in alveoli

faster and shallow breaths - less air in alveoli

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5
Q

lung anatomy

A

right lung - 3 lobes

left lung - 2 lobes

lungs sit in thoracic cavity

ribs go around lungs and intercostal muscles between rib bones

parietal pleura membrane underneath ribcage

visceral pleura membrane surround lung and underneath parietal pleura

intrapleural space inbetween parietal and visceral pleura membranes

intrapulmonary pressure in lungs

intrapleural pressure inbetween pleura membranes

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6
Q

how does the thoratic volume change?

A

inhalation - ribs move up and out, diaphragm moves down

exhalation - ribs and diaphragm move back

atmosphere pressure - 760 mmHg

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7
Q

muscles of inhalation

A

external intercostals: muscles between ribs contract

diaphragm: dome-shaped skeletal muscle contract

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8
Q

breathing when exercising and at rest

A

passive exhalation - relax diaphragm and external intercostals

voluntary exhalation - contract obliques and rectus abdominus to force exhalation, which is faster

+ relaxation diaphragm and external intercostals

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9
Q

lung pressures

A

atmosphere pressure - 760 mmHg

intrapulmonary pressure - 760 mmHg

intrapleural pressure - 757 mmHg

transpulmonary pressure = intrapulmonary pressure - intrapleural pressure

= 3 mmHg

the intrapleural pressure must be lower than the intrapulmontary pressure to keep lungs from collapsing

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10
Q

inhaling and air is moving in, what happens to the intrapleural pressure?

A

the intrapleural pressure decreases to match the pressure difference between the 2 regions

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11
Q

lung compliance

A

“stretchability” of the lung

1 L of air in both A and B

Compliance = change in lung volume / change in lung pressure

A = 1 L / 1 mmHg

B = 1 L / 4 mmHg

the higher the compliance number the easier to stretch the lung

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12
Q

what influences compliance?

A

1) Elastic tissue (Elastin) of lungs (1/3 contribution)

considered recoil or “collapse” forces on the lungs

more elastin = harder to stretch (lower compliance)

2) Surface tension (2/3 contribution)

air-liquid interface (layer of water)

underneath the water layer is epithelium cells (type 1 & 2)

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13
Q

why don’t our alveoli collapse?

A

pulmonary surfactant is made by type 2 cells in the alveoli, made of phospholipids lying over the air-liquid interface

the fatty-acid tails are not attracted to the water, and the hydrophobic head attracts to the water

this balances the water layer and prevents a water droplet from forming and collapsing

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14
Q

pulmonary surfactant function

A

1) reduces surface tension *prevents alveolar collapse
2) microbial defense

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15
Q

Neonatal Respiratory Distress Syndrome (nRDS)

A
  • occurs in premature infants
  • poor lung function, alveolar collapse, hypoxemia (low blood oxygen)
  • lack mature surfactant system

Treatment = administer surfactant (put surfactant inside lungs)

surfactant taken from cows

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16
Q

breathing amounts

A

tidal volume - normal breaths

inspiratory reserve volume - max amount of air you can breath in after a tidal inhalation

expiratory reserve volume - max amount of air you can exhale after tidal exhalation

residual volume - minimum air left in lungs

total lung capacity = residual + expiratory reserve volume + tital volume + inspiratory reserve volume

vital capacity - the amount of air that can be moved (total lung cap - residual)

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17
Q

lung function test

A

FVC (forced vital capacity) = 5 L (after max air inhaled, the total air that can be exhaled)

FEV1 = 5 - 1 L = 4 L (amount of air in lungs after 1 second of exhaling from max inhalation)

FEV1/FVC = 4 L/ 5 L = 0.8 = 80%

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18
Q

lung function test in obstructive lung disease

A

FVC (force vital capacity) = 5 L (normal amount)

FEV1 = 2.5 L at 1 second compared to 4 L at 1 second (normal amount)

FEV1/ FVC = 50%

<80%

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19
Q

asthma

A

asthma: airway spasms in smooth muscle

airway inflammation + airways hyperresponsive

result: airway narrows

induced by allergens, pollution, exercise, cold air

20
Q

emphysema

A

smoking is a major cause

  • destruction of alveolar walls
  • loss of elastin
  • reduces elastic recoil
21
Q

lung function test with restrictive lung diseases

A

FVC = 4 L (lower FVC than normal)

FEV1 = 3.5 L

FEV1/ FVC = 3.5 L / 4 L

= 88%

>80%

22
Q

pulmonary fibrosis

A

pulmonary fibrosis: less compliant due to scar tissue

causes: chronic inhalation of asbestos, coal dust, pollution. sometimes unknown

  • scar tissue is less elastic and hard to expand to inhale more air
23
Q

partial pressure of air

A

oxygen - 21%

nitrogen - 78%

carbon dioxide - 0.03%

partial pressure oxygen = 21/100 x 760 mmHg = 160 mmHg

partical pressure carbon dioxide = 0.03/100 x 760 mmHg = 0.3 mmHg

24
Q

gas exchange in alveoli

A

simple diffusion

blood-gas barrier

type 1 cell wall in alveolar (squamous)

endothelial cell under type 1 cell

then capillary

oxygen and carbon dioxide are small and hydrophobic and can diffuse through cell wall

Fick’s law = surface area x gradient / thickness

25
Q

oxygen pathway

A
  1. O2 enters capillaries from alveoli
  2. O2 rich blood circulates (some CO2)
  3. O2 leaves capillaries into body tissues
  4. CO2 enters capillaries from body tissues
  5. CO2 rich blood circulates (some O2)
  6. CO2 enters alveoli from capillaries
26
Q

how does oxygen go into blood from lungs and body to blood?

A

atmospheric PO2 = 160 mmHg

“stale air” alveolar PO2 = 100 mmHg

pulmonary vein PO2 = 100 mmHg

systemic arteries PO2 = 100 mmHg (no capillaries yet)

body tissue at rest PO2 <= 40 mmHg

systemic veins PO2 = 40 mmHg (same as body tissues)

pulmonary artery PO2 = 40 mmHg (no capillaries)

27
Q

blood composition

A

plasma - 55% (water, proteins, ions, gases, vitamins, glucose, other nutrients, wastes)

white blood cells and platelets - <1% (leukocytes and cell fragments)

red blood cells - 45% (erythrocytes)

28
Q

transport of oxygen

A

oxygen is carried in blood in two ways

1) dissolved in plasma (1.5%)
2) bound to hemo in hemoglobin: inside erythrocytes (98.5%)

4 chains of globin

4 heme groups that contain iron that binds oxygen

oxyhemoglobin (HbO2) ⇔ O2 + Hb

29
Q

oxyhemoglobin dissociation curve

A

resting cell PO2 = 40 mmHg

alveolar PO2 = 100 mmHg

hemoglobin saturation % is around 70% after delivering oxygen to resting cells

saturation goes down if not at rest

30
Q

carbon monoxide (CO) poisoning

A
  • CO from car exhaust & tobacco smoke
  • binds to Hb heme group better than O2
  • treat by administering higher % of O2
31
Q

CO2 pathway

A

at body tissues PCO2 < 46 mmHg

venous PCO2 = 46 mmHg

pulmonary artery PCO2 = 46 mmHg

alveolar PCO2 = 40 mmHg

atmospheric PCO2 = 0.3 mmHg

pulmonary vein PCO2 = 40 mmHg

arterial PCO2 = 40 mmHg

32
Q

carbon dioxide transport

A

1) dissolved in plasma (7%)
2) carbamino form: attached to blood proteins (23%)

“globin” subunits of hemoglobin (not heme)

3) bicarbonate ion (HCO3-)(70%)
- CO2 + H2O combine to form carbonic acid that dissociates into H+ and HCO3- ion
- by lots of enzyme Carbonic Anhydrase in the red blood cell
- H2CO3 unstable and → HCO3- + H+ bicarbonate builds up and will reverse the reaction
- to remove more CO2 from the body tissue, bicarbonate is exchanged for Cl- from the blood

CO2 + H2O → H2CO3 → HCO3- + H+

33
Q

Bohr Effect

A

Borh effect: changes the structure of protein, to make hemoglobin less affinity to oxygen and release more oxygen into cells

increase temperature - temperature changes metabolic rate and protein structure and changes affinity for oxygen (more heat, more oxygen is released from hemoglobin to body cells)

increased pCO2 - oxygen affinity decreases (more oxygen is released from hemoglobin to body cells)

decrease pH (acidic) - H+ like lactic acid is created when exercising, more oxygen is needed and removes CO2 and H+

34
Q

events at the tissue

A

→ high PO2 (100 mmHg), low PCO2 (40 mmHg) from arterioles into capillaries

low PO2 in cells - some dissolved O2 leaves plasma H100

  • O2 leaves Hb from HbO2

high PCO2 in cells- some CO2 binds to Hb

CO2 + H2O ⇔CA H2CO3 ⇔ HCO3 + H+

some CO2 dissolves in plasma

→ low PO2 (40 mmHg), high PCO2 (46 mmHg) from venules to veins

35
Q

events at alveoli

A

→ low PO2 (40 mmHg), high PCO2 (46 mmHg) from pulmonary arterioles into capillaries

some dissolved CO2 leaves plasma into alveoli

CO2 + H2O ⇔CA H2CO3 ⇔ HCO3 + H+ (drive to CO2 + H2O)

CO2 removed from Hb into alveoli

O2 binds to Hb → HbO2

some O2 dissolves in plasma

→ high PO2 (100 mmHg), low PCO2 (40 mmHg) into pulmonary venules then pulmonary veins

36
Q

homeostasis of breathing

A

set point - PO2 = 100 mmHg, PCO2 = 40 mmHg, pH = 7.4

control center → medulla respiratory center

effector → diaphragm, intercostals (breathing muscles)

controlled variable → PO2 PCO2 pH

receptor → chemoreceptors (central and peripheral)

receptor ⇔ control center (⇔ action potentials)

37
Q

chemoreceptors

A

1) peripheral chemoreceptors: in aortic arch, carotid body
2) central chemoreceptors: in medulla oblongata

38
Q

peripheral chemoreceptors

A

sensitive to PO2, PCO2 and pH

if not normal, chemoreceptor detects this and sends APs to the respiratory center in medulla

respiratory center in medulla sends APs to respiratory muscles

39
Q

central chemoreceptors

A

sensitive to pH (hydrogen ions)

CO2 + H2O ⇔CA H2CO3 ⇔ HCO3 + H+ (brain capillary near medulla)

blood brain barrier separates blood from cerebrospinal fluid

cerebrospinal fluid (interstitual fluid)

central chemreceptor in cerebrospinal fluid

CO2 can cross through the barrier and combines with water→ H2CO3 → HCO3- + H+

pH lots of H+ increase AP and increases alveolar ventilation (VA)

40
Q

respiratory acidosis/alkalosis

A

respiratory acidosis: pH < 7.4 due to changes in pulmonary gas exchange

A intercalated cells (removes H+)

respiratory alkalosis: pH > 7.4

B intercalated cells (removes HCO3-)

41
Q

metabolic acidosis/alkalosis

A

metabolic acidosis: pH < 7.4 due to changes in pH unrelated to CO2

  • kidney disease, acetylsalicylic acid overdose, diarrhea

metabolic alkalosis: pH > 7.4 due to changes in pH unrelated to CO2

  • prolonged vomiting
42
Q

how is metabolic acidosis/alkalosis fixed?

A

metabolic acidosis is fixed by increasing the VA (alveolar ventilation)

metabolic alkalosis is fixed by decreasing the VA

43
Q

blood composition and properties

A

hematocrit (blood cells)

properties: biconcave, no nucleus, no organelles

packed with hemoglobin

carbonic anhydrase: CO2 (bicarbonate)

44
Q

anemia and polycythemia

A

anemia: depressed hemocrit % (red blood cells, erythrocytes)

  • fatigue, muscle weakness, breathlessness, increased heart rate

polycythemia: elevated hemocrit %

  • too many blood cells
45
Q

causes of anemia

A

low production of erythrocytes

  • bone marrow issues
  • improper nutrition (eg. iron, Vit B12, folic acid)
  • kidney failure

increased loss of erythrocytes

  • bleeding
  • hemolytic diseases (eg. sickle cell)
46
Q

red blood cell hemostasis

A

red blood cell made from bone marrow

regulated by hormone erythropoietin (EPO)

47
Q

erythropoietin

A
  • peptide hormone
  • acts on bone marrow
  • released from kidney
  • stimulus → low PO2

⇒ 1. anaemia

  1. circulatory issues
  2. lung disease
  3. altitude

Physiology (20 decks)

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