Respiration Flashcards
(58 cards)
1
Q
What is internal respiration? Energy source?
A
intracellular metabolic processes inside the mitochondria. Energy is ATP produced by oxidative phosphorylation
2
Q
Respiratory Quotient Equation
A
RQ = (CO2 produced) / (O2 consumed)
3
Q
What is External Respiration? 4 Steps:
A
External respiration is the entire sequence of events where CO2 and O2 exchange between external and tissue level.
4 Steps:
1. Ventilation
2. Exchange in between air in alveolar and blood
3. Blood transports CO2 and O2 between lungs and tissue
4. O2 and CO2 are exchanged between tissues and blood via diffusion
4
Q
2 Forces in one chest
A
- Intrapleural fluid cohesiveness
- Transmural pressure gradient (atmospheric = 760mmHg ; intrapleural = 756mmHg)
5
Q
Respiratory control centres in the brain
A
- Pons respiratory centre
- Medullary respiratory centre
6
Q
Non respiratory functions of the respiratory system (7)
A
- water loss & heat elimination
- enhances venous return
- maintain acid base balance
- Speech / vocalisation
- Defends against foreign matter
- Removes / modifies materials passing through
- Organ of smell
7
Q
Respiratory Airways (6)
A
- Trachea
- Larynx
- Bronchi
- Nasal passages
- Pharynx
- Bronchioles (alveoli)
8
Q
Trachea and Larger Bronchi
What are they and what are they made of?
A
They are rigid non-muscular tubes
They are made of rings of cartilage
9
Q
Bronchioles. Tissue? Innervated?
A
Tissue = smooth muscle in walls
Innervated by autonomous nervous system
10
Q
Alveoli.
1. What are they?
2. Function?
3. What permits airflow between adjacent alveolar?
4. Types of alveoli
5. what encircles each alveoli
A
- inflatable sacs
- gas exchange
- Pores of Kohn
- Type I = flattened, in wall
Type II = secrete pulmonary surfactant - pulmonary capillaries
11
Q
Relationship of resistance and flow to vessel radius
A
- Blood flows from high to low pressure
- Resistance is a measure of opposition to blood flow - dependent on 3 things: 1. radius 2. viscosity 3. length
R = to 1/r^4 (inversely proportional)
12
Q
Homeostasis of obtaining O2 and excreting CO2 (2 main & explain)
A
- maintain pH level
- CO2 generates carbonic acid (levels must be maintained) - cell survival
- O2 required for energy-generating chemical reactions (energy)
13
Q
Lungs - Components
A
- Diaphragm
- Pleural sac
- Pleural cavity
- Intrapleural fluid
14
Q
Respiratory Mechanics: 3 types of pressure
A
- Atmospheric pressure
- pressure of weight of gas
- 760 mm Hg - Intra-alveolar pressure
- pressure within alveoli
- 760 mm Hg - Intrapleural pressure
- pressure in pleural sac
- 756 mm Hg
15
Q
Boyle’s Law
A
At a constant temperature the pressure exerted by a gas is inversely proportional to the volume
16
Q
Transmural pressure gradient
A
- Transmural pressure gradient across lung wall
- intra-alveolar pushes outward
- intrapleural pushes inward
- 4 mm Hg creates pressure gradient that pushes lungs out, filling the thoracic cavity - Transmural pressure gradient across thoracic wall
- atmospheric pressure pushes inward (760mm Hg)
- intrapleural pushes outward (756 mm Hg)
- 4 mm Hg creates pressure gradient which compresses thoracic wall
17
Q
Respiratory Muscle activity during inspiration and expiration (4 main steps & explain) also state the pressures present in each phase
A
- Before inspiration
- all muscles relaxed
- 760 mm Hg (intra-alveolar)
- 756 mm Hg (intrapleural) - During inspiration
- diaphragm contracts (flattens)
- external intercostal muscles contract
- ribs elevate
- enlarges the thoracic cavity
- 759 mm Hg (intra-alveolar)
- 754 mm Hg (intrapleural) - During quiet expiration (passive)
- diaphragm relaxes (lifts)
- external intercostal muscles relax
- ribs fall due to gravity
- 761 mm Hg (intra-alveolar)
- 756 mm Hg (intrapleural) - During active expiration
- abdominal muscles exert force on the diaphragm
- internal intercostal muscles contract
- reducing size of thoracic cavity more so than during quiet passive
18
Q
Major inspiratory muscles and by which nerves they are innervated
A
- Diaphragm
- phrenic nerve - External intercostal muscles
- intercostal nerve
19
Q
2 Pressure related issues in the lung
A
- Traumatic Pneumothorax
- puncture in chest wall
- air flows down gradient from atmosphere into pleural cavity
- abolishes transmural pressure gradient. Results in intrapleural pressure of 760 mm Hg - causes collapsed lung (pleural cavity exerts pressure on lung) - Spontaneous Pneumothorax
- punture in the lung wall
- air moves down gradient from intra-alveolar to intrapleural
- abolishes the transmural pressure gradient
- intrapleural pressure of 760 mm Hg
- results in collapsed lung
20
Q
COPD
A
Chronic Obstructive Pulmonary Disease
- increases airway resistance
- expiration is more difficult than inspiration
21
Q
Airway collapse during forced expiration (all 4 scenarios including normal)
A
- Quiet breathing
- airway resistance is low
- intrapleural pressure is less than airway pressure - During exercise
- intrapleural pressure is higher
- but so is intra-alveolar and therefore resistance is low (same gradient) - Maximal forced expiration
- both intrapleural and intra-alveolar increases markedly
- airway pressure falls below intrapleural
- causing constriction of airways, preventing further expiration - Obstructive lung disease
- premature airway collapse
- 2 causes- increased airway resistance magnifies pressure drop in airways
- intrapleural pressure is higher than normal due to a loss of lung tissue responsible for the recoiling of the lung
- airways collapse at higher lung volumes
- fewer alveoli are ‘freshened’ with each breath
22
Q
Pulmonary Elasticity:
Compliance & Recoil (2 factors)
(what and explain)
Syndrome in babies
A
Compliance is how much effort is required to stretch the lungs
- less compliant = more work required
Recoil is how readily the lungs rebound after being stretched (expiration)
- return to pre-inspiratory volume
2 Factors
1. Highly elastic connective tissue in the lungs
2. Alveolar surface tension
- pulmonary surfactant reduces tendency of alveoli to recoil
- the greater the surface tension the less compliant
- Newborn respiratory distress syndrome: not enough pulmonary surfactant, therefore surface tension cannot be reduced
23
Q
2 Factors opposing alveoli collapse
A
- Surfactant
- lipids / proteins
- reduces surface tension
law of LaPlace
P = 2T/r
if there are 2 alveoli of different sizes, the smaller one will collapse and empty its air into the larger one
Pulmonary surfactant reduces surface tension of a smaller alveoli more than that of the larger one, preventing the process mentioned above. - Alveoli Interdependence
- when alveoli collapse in a group of interconnected alveoli, they stretch and recoil in resistance, pulling the alveoli open.
24
Q
Work of Breathing
1. Requirements
2. What increases it?
A
- 3% of total energy expenditure
- work increased when pulmonary compliance is decreased, when airway resistance is increased, when elastic recoil is decreased
25
Measure breathing
Spirometer
- air-filled drum floating in a water filled chamber
- rise and fall of drum when breathing in and out of tube
- measures the magnitude of the volume change
- cannot measure residual volume
26
Lung Volumes and their descriptions as well as values:
(9)
1. Tidal volume (TV)
- volume flowing in / out
- 500 ml
2. Inspiratory reserve volume (IRV)
- extra volume that can be maximally inspired over and above TV
- 3000 ml
3. Inspiratory Capacity (IC)
- Max inspired (IRV + TV)
- 3500 ml
4. Expiratory reserve volume (ERV)
- Max actively expired over and above TV
- 1000 ml
5. Residual Volume
- minimal volume remaining in lungs after maximal expiration
- 1200 ml
6. Functional Residual Capacity (FRC)
- volume INSIDE lungs after passive expiration
(include ERV - as it hasn't occured yet)
FRC = ERV + RV
7. Vital Capacity (VC)
- maximal volume that can be moved out following max inspiration
- VC = IRV + TV + ERV
- 4500 ml
8. Total Lung Capacity (TCL)
- maximal volume that the lungs can hold
- TLC = VC + RV
- 5700 ml
9. Forced Expiratory volume in one second (FEV1)
- volume of air that can be expired during the first second of expiration
27
Obstructive Lung Disease
(abnormal spirograms)
Experiences difficulty emptying the lungs
TLC is normal
FRC and RV are elevated due to air being trapped in the lungs
VC is reduced
FEV1 reduced significantly, airflow rate reduced due to airway obstruction
28
Restrictive Lung Disease
(abnormal spirograms)
lungs cannot be filled, and therefore TLC and VC are reduced
lungs are less compliant
RV is normal
VC that can be inhaled in one second is the NORMAL 80%
therefore FEV1 / VC useful in distinguishing between obstructive and restrictive.
29
Pulmonary Ventilation
minute ventilation
volume of air breathed in and out in one minute
PV = TV x Respiratory rate
TV = 500 ml
30
Alveolar Ventilation
more NB than pulmonary
the air exchanged between the atmosphere and the alveoli per minute
= Functional respiration
less than pulmonary due to dead space (150ml)
AV = (TV - dead space) x Respiratory Rate
(500 - 150) x RR
31
Effects of local changes in O2 on the pulmonary and systemic arterioles
Pulmonary Arterioles:
Increased O2 = Vasodilation
Decreased O2 = Vasoconstriction
Systemic Arterioles:
Increased O2 = Vasoconstriction
Decreased O2 = Vasodilation
32
Local controls to match airflow and blood flow to an area of the lung
CO2 acts locally on bronchiolar smooth muscle
O2 acts locally on arteriolar smooth muscle
33
Gravity determines perfusion
The top of the lung receives less air and blood than the bottom of the lung
However the top of the lung receives more air than blood (relatively)
and the bottom of the lung receives more blood than air (relatively)
Therefore the ventilation-perfusion ratio is higher at the top of the lung
34
Fick's Law of Diffusion
Effect of a factor on the rate of net diffusion
Increased concentration increases rate
Increased surface area increases rate
Increased solubility increases rate
Increased molecular weight decreases rate
Increased distance decreases rate
35
Gas Exchange
What is Partial Pressure
O2 and CO2
total pressure x fractional composition
CO2 and O2 move down their partial pressure gradients in peripheral tissue
O2 = 100 -> 40 mm Hg
CO2 = 46 -> 40 mm Hg
36
2 Locations of gaseous exchange
1. Capillary bed alveoli
2. capillary bed tissue level
36
Gaseous Exchange
Explain process
PO2 in systemic is higher than tissue cells
PCO2 in systemic is lower than tissue cells
Therefore oxygen diffuses from systemic to tissue.
CO2 moves from tissue to systemic
blood leaving systemic is high in CO2 and low in O2. This blood returns to the right side of the heart
At pulmonary capillaries blood gains oxygen and releases CO2
36
Additional factors that affect the rate of gas exchange
1. surface area increases, so does rate
2. increased thickness of barrier between blood and air decreases rate
3. rate of gas exchange is directly proportional to diffusion coefficient
37
Classification of Hypoxia (4)
Types
Definition
Causes
Hypoxic Hypoxia
- low arteriole PO2
- caused by high altitude
Anaemic Hypoxia
- decreased O2 bound to Hb
- caused by anaemia / blood loss
Ischemic Hypoxia
- reduced blood flow
- caused by thrombosis
Histotoxic Hypoxia
- cell poisoning and inability to use O2
- caused by cyanide poisioning
38
Haemoglobin
What does it consist of?
Saturation?
Reaction:
4 highly folded polypeptide chains and 4 iron containing heme groups
If 4 O2 molecules bind to an Hb it is 100% saturated
Hb + O2 <--> HbO2
(oxyhaemoglobin)
39
Oxygen-haemoglobin dissociation curve
Plateau?
Steep?
% saturation depends on PO2 of the blood
Plateau = 60-100 mm Hg
@ 100 mm Hg = 97.5 % saturation
@ 60 mm Hg = 75 %
Steep = 0-60 mm Hg
@40 mm Hg = 25%
40
Haemoglobin acts as storage depot for O2
Why?
How?
To facilitate a large net transfer of O2
Hb binds to O2
PO2 lowers as it only counts dissolved O2 molecules
Therefore blood PO2 falls below alveoli PO2 which favours more transfer of O2 into the blood (down the concentration gradient)
Note that despite binding of Hb to O2 there are still technically the same amount of Oxygen molecules to when there was no Hb
41
Haemoglobin's high affinity for CO2
what does it form?
type of sickness?
Carboxyhaemoglobin (HbCO)
Carbon monoxide poisoning
treated with 100% oxygen
Small amounts of CO2 makes large amounts of Hb unavailable
42
Carbon dioxide transport in the blood (3 ways)
Location of Hb and enzyme
Movement of bicarbonate
1. Physically dissolved
2. bound to Hb
3. as a bicarbonate ion
Hb is only found in the red blood cells as well as the enzyme carbonic anhydrase (catalyses production of HCO3 - bicarb)
Bicarb diffuses down gradient out of red blood cell and into plasma
43
Controls of Respiration in the brain
1. Medullary Respiratory Centre
- Dorsal respiratory group (DRG)
-> inspiratory neurons
- Ventral respiratory group (VRG)
-> overdrive mechanism
2. Pons Respiratory Centre
- Apneustic
- > prevents switch off of inspiratory neurons
- Pneumotaxic centre
-> switch off inspiratory neurons
44
Pre-Botzinger Complex
Generates respiratory rhythm
Self induced action potentials
Driving the dorsal respiratory group
45
Hering Breuer Reflex
function?
mechanism & tissue?
Prevents overinflation
Pulmonary stretch receptors in the smooth muscle
46
Location of the peripheral chemoreceptors (2)
state what and the location
1. the carotid is located carotid sinus
2. aortic bodies located in the aortic arch
47
Chemical factors that determine magnitude of ventilation (O2 and CO2 - receptor types)
1. PO2 = peripheral receptors
2. PCO2 = chemoreceptors
48
Factors influencing ventilation unrelated to need for gas exchange
1. sneezing / couching
2. inhaling poisonous agents which trigger breathing to stop
3. pain anywhere in the body (panting)
4. emotions
5. reflexly inhibited during swallowing
49
Abnormalities in arteriole PO2
1. Hypoxia
- insufficient O2
2. Hyperoxia
- PO2 above normal
3. Hypercapnia
- excess CO2
- caused by hypoventilation
- respiratory acidosis
4. Hypocapnia
- low PCO2 levels
- hyperventilation
- respiratory alkalosis
5. Hyperventilation
- CO2 increased
- fast & deep breathing
50
Effects of depth on the body
Every 10m pressure increases by 1 atmosphere
Nitrogen dissolving in neuronal membranes
Nitrogen Narcosis
51
Deep diving marine animals
do not fill lungs under pressure, breath at surface then dive
change in cartilage distribution
fat absorbs nitrogen safely
52
Effects of height on the body
Decrease in partial pressure
at 18 000 feet atmospheric pressure is 50% (380 mm Hg)
anything above 10 000 feet / 3048 meters = unfavourable portion of binding curve
- results in hypoxic hypoxia (acute mountain sickness)
-> hypocapnia induced alkalosis
53
Acclimatisation
what is it?
how it works:
- compensatory mechanism to ensure sufficient O2 and normal acid-base balance
- increase Hg carrying capacity
- increase O2 binding capacity
- synthesis of diphosphoglycerate
- increased mitochondria -> increased respiration capacity in the cells
54
Types of Chronic Obstructive Pulmonary Disease: (4)
1. Chronic bronchitis
- narrowed airways
- bacterial infections
2. Asthma attack
- cutting off all airflow
- inflammation & wall thickening (histamine induced)
3. Emphysema
- collapse of smaller airways
- chronic exposure to irritants (smoke)
- irreversible
- requires excessive energy to expire and inspire
4. Heart failure and pulmonary oedema
- left heart weakened
- accumulation of fluid in the lung
- increased pulmonary blood pressure
54
What is COPD?
Increased resistance
More air in the lungs but less gaseous exchange
55
