Respiratory physiology Flashcards
(109 cards)
1
Q
Whats the biochemical definition for cellular respiration?
A
The process in which nutrients are converted into useful energy in a cell
2
Q
Whats the physiological defintion for gaseous exchange?
A
The process by which an organism exchanges gases with its environment- process and regulation
3
Q
Whats are the roles of the respiratory system?
and how do these things occur?
A
- gas exchange
- regulation of blood (tissue) PH: altered by changing blood CO2 levels
- voice production: movement of air past vocal fold makes sound and speech
- Olfaction: smell occurs when airborne molecules are drawn into nasal cavity
- protection: against particles/ microorganisms by preventing entry and removing them
4
Q
Label the respiratory system…
A
5
Q
What are the two zones the respiratory system has and what included in these systems?
A
1. Conductive zone
- URT (upper respiratory tract)
- Tracheobronchial tree
2. Respiratory zone
- Resoiratory bronchioles to alveoli
- Site for gas exchange
6
Q
Whats the roles of the nasal cavity?
A
- passage for air
- cleans the air
- humidifies, warms air
- smell
- acts along with paranasal
- sinuses (resonating chambers)
7
Q
Whats the structure in the nose that causes turbulalce? What does this mean for keeping the nose/body healthy?
A
The Conchae causes turbulance of air (gives large surface area)
large particles are blocked from coming in
8
Q
What do sinuses help with?
A
- lighten skull
- protection
9
Q
Whats the pharynx and what are the regions of it?
A
The Pharynx is a common opening for digestive and respiratory systems
the three regions of the pharynx are;
- Nasopharynx
- Oropharynx
- Laryngopharynx
10
Q
What are the functions of the larynx?
A
- maintain an open passageway
- Epiglottis and ventricular folds prevent swallowed material from moving into larynx
- vocal folds are the primary source of sound production
11
Q
What are the unpaired cartilages of the larynx?
A
The thyroid, cricoid and epiglottis
12
Q
What are the paired cartilages of the larynx?
A
The arytenoid, corniculate and cuneiforms
13
Q
Whats the functions of the tracheobronchial tree ?
What must we ensure for correct function?
A
Functions:
- passageway for air movement
- ciliated for the removal of debris
For the correct function to occur you must ensure:
- Theres limited turbulance
- minimal size (dead space)
14
Q
What does the trachea branch into and where does this lead?
Where is cilia lost in the traceobroncial and why?
A
The trachea branches into 2 bronchi, one to each lung
In the terminal bronchiole you lose the ciliated epithelium and get squamous epithelium instead which allow for gaseous exchnage with the blood
15
Q
Label the alveoli?
A
16
Q
Tell me the types of cells found in the alveoli and some of the properties/ roles?
A
1. Type 1 alveolar cells (septal cells)
- in contact with capillary
- simple squamous cells where gaseous exchnage occurs
2. Type 2 alveolar cells
- free surface has microvilli
- secrete alveolar fluid which contains surfactant
3. Alveolar dust cells
- macrophages also found in alveoli to remove debris
17
Q
The lungs ‘float’ in the thoracic cavity because they are surrounded by a thin layer of what?
A
pleural fluid
18
Q
Is the lung directly attached to any muscle?
A
no
19
Q
The continual transfer of fluid into the lymphatic channel maintains a negative pressure between what?
A
The visceral surface of the lung pleura and the parietal pleural surface of the thoracic cavity
20
Q
Label the muscles that are used for ventilation?
A
21
Q
What are the passive elements of ventilation?
A
- elastic return in lungs
- elastic recoil of ribs
- surface tension in lungs
22
Q
Whats are the types of pressure in the lungs and where are they found?
A
- Pleural pressure: pressure in the intrapleural space (always a slightly negative pressure)
- Alveolar pressure: pressure inside the lung alveoli
- Transpulmonary pressure: alveolar pressure- pleural pressure (force that tends to distend the alveoli)
23
Q
Describe the changes in pressure in the lungs during inspiration and just after?
A
- the Barometric air pressure (PB) is equal to alveolar pressure (Palv) and there is no air movement
- increases thoracic volume results in increased alveolar volume and decreases alveolar pressure
- Barometric air pressure is greater than alveolar pressure and air moves into the lungs
- End of inspiration
- Decreased thoracic volume results in decreased alveolar volume and increased alveolar pressure
- alveolar pressure is greater than barometric air pressure, and air moves out of the lungs
24
Q
Whats meant by compliance of the lungs?
Name some conditions that decrease the compliance
A
the ease in which the lungs and thorax expand
conditions which decrease the compliance: pulmonary fibrosis and pulmonary oedema (fluid in the lungs)
25
What is compliance altered by? Which one has the greatest effect?
* elastic fibres of the lung/chest
* elastic fibres caused by surface tension in alveoli (this has the greatest effect)
26
Whats **surfactant** and what's it a mixture of?
**Surfactant** is an surface-active agent in water, gently reducing the surface tension of water
**Surfactant is a mixture of:**
* Dipalmitoyl phosphatidylcholine, (amphiphilic) (roughly 40%)
* Other phospholipids (roughly 40%)
* Surfactant apolipoproteins (SP-A, -B, -C, -D) (roughly 10%)
27
Whats surfactant formed in specifically?
Whats the secretion of surfactant regulated by?
**Formed** in lamellar bodies (LB) in type II alveolar cells
**Secretion** of surfactant is regulated by increased tidal volumes
28
What are the functions of the surfactant?
****
* **Reduced work in inspiration** (increases compliance). Results in 1/12 of the surface tension of a pure water air interface
* **Stabilises alveoli** (Laplace)
* **Reduced alveolar pressure** help keep alveoli dry; helps prevent pulmonary oedema
* Crucial for **expansion of lungs at birth**
29
Whats the definition of the following...
1. **Respiratory rate**
2. **Minute ventilation**
3. **Anatomic dead space (ADS)**
4. **Alveolar ventilation (AV)**
**1. Respiratory rate:** The number of breaths per minute
**2. Minute ventilation:** The amount of air moved in and out of the respiratory system per minute
**Tidal volume (Tv) x Respiratory rate (RR)**
**3. Anatomic dead space (ADS):** part of the respiratory system where gas exchnage does not take place (found in conducting zone and bronchioles is roughly 150 mls)
**4. Alveolar ventilation (AV):** Volume of air per minute entering the parts of the respiratory system in which gas exchnage takes place
**(Tv - ADS) x RR**
30
Whats **partial pressure?**
The pressure exerted by each type of gas in a mixture
31
Whats **Dalton's law**?
Whats the general formula and then that to do with atmospheric gases?
total pressure = sum of partial pressure
**Ptotal = P1 + P2 + P3 + ...**
involving atmospheric gases
**P= pN2 + pO2 + PCO2 + pH2O**
32
What are the 3 facotrs that changes the alveolar pressure of oxygen and carbon dioxide in the alveolus?
1. **Alveolar ventilation rate (v)**
2. **increase Oxygen consumption and carbon dioxide production (exercise)**
3. **Atmospheric pO2 and pCO2 alter with atmospheric pressure (altitude)**
33
What does **Fick's law** explain?
Whats the equation? and what each represent?
The diffusion of gases
**Rate of diffusion: K x A x (P2 – P1)/ D**
K= diffusion constant
A= area for gas exchange
P2 and P1= difference in partial pressures of gas on either side of diffusion barrier
D= distance (thickness of diffusion barrier)
34
What does the The respiratory membrane consist of ?
* layer of fluid lining the alveolus, containing surfactant
* alveolar epithelium
* epithelial basement membrane
* capiallary basement membrane (may fuse with epithelial basement membrane)
* capillary endothelium
35
What factors affect the rate of gas transfer?
* area for diffusion (emphysema) (area of functioning alveoli in contact with functioning capillaries)
* Thickness of path (here fluid path- cyctic fibrosis, pulmonary oedema, alveolar blocks)
* Changes in partial pressure difference over the memrbane (altitude etc.)
36
What are the causes that lead to an increase in pulmonary alterial blood pressure?
1. the speed of blood transit through the pulmonary capillaries increases
2. collapses vessels in the lungs to open so overall alveolar perfusion increases
37
What two factors are involved with the regulation of oxygen and carbon dioxide transfer between alveolus and blood? Tell me about the perfusion and ventilation in each part?
**1. Rate of alveolar ventilation (v):** upper parts of the chest are better ventilated but have a worse perfusion
**2. Blood flow (perfusion) (Q):** lower parts of the lungs are perfused better but have a worse ventilation
38
are all the alveoli ventilated and perfused equally?
no
39
What does the ventilation-perfusion rate provide?
a balance between the alveolar ventilation and alveolar blood flow
40
What are the special blood vessles surrounding alveoli in hypoxic conditions (low oxygen)?
* When pO2 within the alveoli decrease there is a decrease in blood flow to alveolus: this is called **hypoxic vasoconstriction**
* Oxygen sensitive K+ channels in the smooth muscle membrane of the pulmonary arteriole close, the cell depolarises so these arterioles partially close
* it is important in the pulomary circulation helping to match perfusion with ventilation
41
Whats **Henry's law**?
concentration of dissolved gas= partial pressure x solubility coefficient
42
Tell me the colour changes of the Hb in oxygenation? and the equation to go alongside it
**Hb** (deoxyhaemoglobin: blueish) **+ O2 + HbO2** (oxyhaemoglobin:red)
43
Hb is a tatramer (4 molecules together) so what is Hb reaction with oxygen really like? (equation?)
Hb + 4O2 --\> Hb(O2)4
44
What colour is **Methaemoglobin Hb(Fe3+)?**
brownish
45
What is a **sigmoid curve** typical for?
allosteric activation and gives greater oxygen release to tissues on exercise
46
Whats **allosteric activation?**
binding of one ligand enhances the interaction between substrate and other binding sites
47
The binding of oxygen to one haemoglobin subunit induces what?
conformational changes in the remaining active site, which then enhances their affinity
48
What are the Advantages of an S-shaped (sigmoid curve) curve for Hb-O2 associaton?
49
In the Hb-O2 association curve, when the PH decreases, what happens to the curve and what effects does it have in the body?
Why does the curve do this?
The curve shifts to the right:
1. increases hydrogen ions
2. increased carbon dioxide
3. increased temperature
4. increased BPG
The curve moves to the right as more oxygen is delivered to the tissue
50
What does **myoglobin** act as in muscles and tissues?
an oxygen store
51
Draw graphs of the Bohr effect and the effect of PH, pCO2 and temperature on the pO2/ % of oxygen saturation
52
what type of monomer is myoglobin and what binding does it show?
Myoglobin is a high affinity monomer and shows non-allosteric binding
53
What does 2,3,-Biphosphoglycerate alter the position of?
The Hb-O2 curve
54
Show how 2,3-biphosphoglycerate is made from glycolysis
55
What have an higher affinity for oxygen, fetal or adult Hb, and why?
Foetal Hb has a higher affinity for O2 due to its failure to interact with 2,3-Biphosphoglycerate
56
What are the factors that change the haemoglobin affinity for oxygen?
1. Hydrogen ion concentration [H+]
2. carbon dioxide partial pressure, pCO2
3. temperature
4. [2,3-DPG]
5. carbon monoxide, CO
57
What is the main oxidative reaction?
What does this reaction produce energy for?
Main oxidative reaction:
**O2 + 4H+ + 4e- --\> 2H2O (NADH/H+)**
This reaction produces energy for:
**ADP + PO42- --\> ATP**
58
for normal intracellular chemical reactions to occur in the respiratory enzyme systems, what does the partial pressure of oxygen need to be?
Above that level, what is the main limiting factor for the reaction?
**pO2 \> 1mmHg**
Above this level, the main limiting factor for ATP production is not oxygen but the ADP in the cells
59
Whats the formula for the concentration of dissolved gas?
**concentration of dissolved gas= pressure x solubility coefficient**
60
What has a higher solubility, carbon dioxide or oxygen?
CO2 has a higher solubility than oxygen
61
What are the three ways that CO2 is transported in the blood? what are the % of each?
1. **As CO2 transported in solution-** 6%
2. **As Hgb•CO2-** 24%
3. **As HCO3--** 70%
62
Tell me how **hydrogen carbonate ions** are formed, along with equations and what happens afterwards and why?
1. CO2 enters the blood and diffuses into the cytoplasm of RBC
2. Here, the CO2 reacts with water to form carbonic acid. This is **catalysed by carbonic anhydrase**
**CO2 + H2O --\> H2CO3**
3. carbonic acid is unstable so dissociates into hydrogen carbonate ions and hydrogen ions
**H2CO3 --\> HCO3- + H+**
4. The Hydrogen carbonate ions then diffuse out of the cell into the blood
5. this causes chloride shift (where **Cl- diffuse into the** **cell** in order to balance the charges). **Water also diffuses into the cell** with the Cl-
63
Whats the equation for the carbamino formation at the N-terminus of proteins, especially haemoglobin?
**CO2 + Hgb --\> Hgb•CO2**
64
When carbonic acid dissociates into HCO3- and H+, what does the H+ react with and whats formed?
**H+ + Hgb- --\> HHgb**
65
In the reactions with carbon dioxide in the RBC, if more H+ is available what happens?
The reactions become reversable
66
Whats the **Haldane effect?**
Whats a consequence for this effect?
When oxygenation of blood in the lungs displaces carbon dioxide from haemoglobin which increases the removal of carbon dioxide
consequently, oxygenated blood has a reduced affinity for carbon dioxide
67
Tell me the steps to the Haldane effect...
1. H+ ions react at the carbamino N-terminal (-NH3+) displacing CO2
2. this increases the acidity (H+) and also causes bicarbonate ions to form carbonic acid
3. this then dissociates into water and carbon dioxide which is released into the alveoli
4. hence, the lungs increased CO2 is lost from the blood
68
How is the Haldane effect different in the **tissue capillary** as opposed to the lung capillary?
* deoxygenated blood carries more CO2
* transfer of carbon dioxide from tissues greatly enhanced by the opposing transfer of oxygen and altered character of Hb and oxyHb
69
Is OxyHb a strong or weak acid?
it is a strong acid
70
What compound induces the Haldane effect?
carbamino's
71
Increased plasma carbon dioxide lowers blood PH and causes what effect?
An increase in respiration rate.
72
What regulates breathing?
Tightly controlled by the blood levels of carbon dioxide (plasma pH) rather than oxygen
73
Whats the ventilation pattern?
* what aspect of the PNS is it associated with?
* where does it occur?
* voluntary or involuntary ?
* associated with the **autonomic nervous system**
* occurs through the **CNS respiratory centres**
* it is involuntary with limited voluntary override
74
What are the 4 main groups in the respiratory centre?
Where are they located?
What do they have the greatest effect on?
**1. Dorsal respiraory group**
located in: dorsal medulla
Main effect: causes inspiration
**2. Vental respiratory group**
located in: ventrolateral medulla
Main effect: modifies expiration and inspiration
**3. Pneumotaxic centre**
located in: dorsally in the superior pons
Main effect: mainly controls breathing rate and depth
**4. Apneustic centre**
located in: lower pons
Main effect: stimulates the inspiratory neurones of the DRG and VRG
75
What sensory termination forms in the dorsal respiratory group?
sensory termination of both the vagal and the glossopharyngeal nerves, which transmit sensory signals into the respiratory centre
76
What receptors send their signal via the vagus/glossopharyngeal nerves?
1. peripheral chemoreceptors
2. baroreceptors in chest
3. several receptors in lungs (stretch etc.)
77
During inspiration what happens with the activity of inspiratory neurons?
it increases steadily
78
At the end of inspiration, the activity shuts off abruptyl and how does expiration then occur?
by virtue of elastic recoil of lungs
79
Whats the cycle for quiet breathing, incorporating the necessary respiratory groups ?
80
Whats the apneustic centre regulated by?
1. the Pneumotaxic centre
2. vagal input (stretching of lung)
81
When the pneumotaxic signal is strong, what happens to the switch off of inspiration?
it occurs sooner, when weak the inspiration must shut off slightly later
82
What are the 2 main roles of the pneumotaxic centre?
* limits length of inspiration
* increases rate of breathing
83
does the ventral respiratory group have an effect on quiet respiration?
no
84
What effects does the ventral respiratory group cause during exercise and theres forced breathing?
* the stimulation of some neurones in the ventral group leads to stronger inspiration
* the ventral respiratory area contributes to both inspiration and expiration
* important for sending signals to the abdominal muscles during very heavy exercise
85
Whats the respiratory cycle for forced breathing, and what happens in the necessary groups?
86
What respiratory groups does the following apply to?
1. basic rhythmic activity
2. regulatory activity
1. basic rhythmic activity: **DRC**
2. Regulatory actibity: **Pneumotaxic and apneustic**
87
What is the respiratory centre's activity regulated by?
1. **Local reflexes**
2. **Chemical control**
3. **cortical factors**
88
Whats an example of a local reflex that affects the repsiratory centres activity?
what is it?
**Herring-Breuer reflex**
* stretch receptors in chest wall and in the bronci and bronchioles (over smooth muscle) sens impulse to the brain to terminate inspiration
* protective reflex expansion of the lung
* coordinate **apneustic and pneumotaxic centre**
89
Whats the Herrin-Breuer reflex's control in infants and adults?
**_infants_**
reflex plays a role in regulating basic rhythm of breathing and preventing over inflation of lungs
**_Adults_**
Reflex is important only when tidal volume is larger due to exercise
90
What are the two examples of chemical control in the respiraotry centre activity?
1. **Central (medullary) chemorecpetors** (most important control)
2. **peripheral chemoreceptors**
91
How does the central (medullary) chemoreceptors help with respiratory activity?
These receptors are sensitve to incrases in arterial CO2 and decreases in arterial PH.
It is sensitive to the Ph of the CSF
92
When does the peripheral chemorecpetors have an effect on respiratory activity and what type of effect does it have?
* has effects on respiratory only at low pO2
* haemoglobin-oxygen system delivers almost normal amount of oxygen to the tissue once PO2 \> 80mmHg (Hb is 95% saturated here)
* this is not true for CO2-blood and tissue PCO2 changes inversely with the ventilation rate
* peripheral chemoreceptors (outside the brain respiratory centre) plays a role only when the blood oxygen falls to low (80% Hb saturation)
Oxygen centres monitor the amount of oxygen in the blood. And are activated when % of oxygen falls below a certain level
93
Name 2 types of oxygen sensors
1. **carotid body**
2. **aortic bodies**
94
Give some examples of cortical factors that can affect respiratory activity?
1. upper cortex speech
2. swallowing
3. exercise (voluntary respiratory control)
95
What does the carotid body chemoreceptor cells respond to?
What sort of effects does it cause?
**hypoxia**
* inhibiting K+ channels
* depolarisation and activation of voltage-dependant Ca2+ channels
96
Carotid body effects leads to Ca2+ channels opening, what does the influx in calcium result in?
exocytosis of the neurotransmitter dopamine that increase the activity of the afferent chemosensory fibres
97
What else can effect the carotid bodies?
CO2 and H+
98
When you hyperventilate before jumping into water, why do you run the risk of drowning?
The pCO2 is lowered and Ph is increased which lowers out respiratory drive
When you then swim, you burn off the O2 supply
eventually you would pass out and drown
99
Whats the reaction between CO and Hb?
Whats the name of the product and the colour if it?
**Hb + CO --\> HbCO** (carbmonoxyhemoglobin; bright red, pink)
100
Even though the oxygen content of the blood is greatly reduced in carbon monoxide poisoning, why may the arterial PO2 of the blood still be normal?
As oxygen is still dissolved in the plasma
101
As the PO2 is not reduced in CO poisoning, what is not stimulated?
The carotid/ aortic body that stimulates increased respiration rate in repsonse to lack of oxygen
102
How is CO poisoning treated?
**By administering a mixture of O2 and CO2.**
O2 displaces the CO
CO2 which strongly stimulates the respiratory centre which increases breathing rate
103
WHats **Hypercapnia?**
high tissue CO2
104
Whats are the 4 types of hypoxia?
1. **hypoxic hypoxia**
2. **anemic hypoxia**
3. **stagnant hypoxia**
4. **histotoxic hypoxia**
105
Whats **Hypoxic hypoxia?**
Whats the risks?
When the PO2 of arterial blood is reduced.
Theres a risk of loss of consciousness. Could be causes due to an altitude change
106
Whats **Anemic-hypoxia?**
When theres a low haemoglobin content.
Also, in CO poisoning, effective Hb content is reduced by HbCO complexes
107
Whats **stagnant hypoxia** due to?
Whats can it result in?
It is due to poor circulation.
It can lead to congestive heart failture (or localised restriction)
108
Whats **Histotoxic hypoxia?**
Give an example of how this occurs in the body
The inhibition of tissue oxidative processes by poisons
e.g. cyanide- combines with cytochrome oxidase preventing O2 from serving as the ultimate electron acceptor
109
Whats do the carotid and aortic body chemoreceptors detect?
low levels of oxygen
