Week 24 Flashcards

Question

What is Boyle's Law, explaining changing pressure involved in breathing?

Answer 1

As pressure increases, volume decreases, vice versa. Therefore, ribs falling and diaphragm rising, compresses air and increases pressure. This drives the flow of air outward.

Answer 2

Compliance: how stretchy are the lungs? Surface Tension: surfactant reduces surface tension. Without it, alveoli would collapse Airway resistance: - airflow = (P alveoli- P atmosphere)/Resistance - Resistance increases on exhalation as bronchiole diameter decreases

Answer 3

Respiratory centres in the Medulla oblongata and midbrain control breathing. - Pontine respiratory Centre in mid brain - Dorsal Respiratory Group in medulla - Ventral Respiratory Group in medulla Centres respond to multiple signals eg chemoreceptors, proprioceptors (indicate position)

Answer 4

Dorsal respiratory group controls this. Has active or inactive phase: Active phase (2secs): - Diaphragm and intercostal muscles contract, - Normal quiet inhalation Inactive phase (3 secs): - Diaphragm and intercostal muscles relax, lungs recoil, - Normal quiet exhalation

Answer 5

Dorsal respiratory group: - Diaphragm contracts and external intercostal muscles contract (Forceful breathing) Ventral respiratory group: - Accessory inhalation muscles contract (ie scalene pectoralis minor) (forceful breathing) Ventral respiratory group: - Accessory exhalation muscles contract (internal intercostal, external oblique, transverse abdomis, rectus abdominis) (forceful exhalation)

Answer 6

- Voluntary control: useful for communication - Other CNS areas (Eg for emotion): Ventilation can be increased or reduced due to emotion; also transient effects such as gasping, sobbing etc - Motor cortex (eg during exercise): Information from motor cortex related to level of effort involved in exercise feeds into respiratory control centre (proprioceptors)

Answer 7

- Not all of the air reaches the alveoli, but ventilates the trachea, bronchi and bronchioles. There is no/very low perfusion of these areas so gas exchange cannot occur.

Answer 8

the amount of times you inhale in a minute. This exchanges approximately 500ml of air

Answer 9

Amount taken in and exhaled on a normal breath

Answer 10

Amount taken in in a deep breath

Answer 11

Amount exhaled in a forces exhalation

Answer 12

Air not exchanged but stays in lungs to keep inflated

Answer 13

Tidal volume + inspiratory Reserve Volume

Answer 14

Inspiratory Reserve Volume+ Tidal Volume+ Expiratory Reserve Volume

Answer 15

Vital capacity + Residual Volume

Answer 16

Obstructs air passage

Answer 17

Expansion of lungs restricted

Answer 18

Oxygen diffuses from alveoli into pulmonary capillaries. Carbon dioxide moves in the opposite direction

Answer 19

Oxygen diffuses from the systemic capillaries into the tissues and carbon dioxide in the opposite direction

Answer 20

ases moves from the alveolar air and blood by passive diffusion. Normally, blood is in contact with the alveoli for 0.75 seconds, and PO2 reaches equilibrium in about 0.25 seconds; therefore, PO2 is not diffusion limited. If exercising, blood flow increases so time for diffusion decreases

Answer 21

The total pressure of a gas mixture is equal to the sum of the pressures of each gas in it. Partial pressure = the pressure of an individual gas; can be measured by multiplying the % of that gas by the total pressure

Answer 22

Composition of air: - 78.09% nitrogen PP=593.5mmHg - 20.95% oxygen PP=159.2mmHg - 0.93% argon (& other inert gases) - 0.03% carbon dioxide PP= 0.23mmHg Air pressure: - at sea level = 760 mm Hg = 1 atmosphere

Answer 23

- Alveolar walls - Blood vessel walls

Answer 24

- Alveolar wall has elastic fibres for movement and stretch - Macrophages (dust cells) for filtration - 2 types of alveolar cell (pulmonary epithelial cells)

Answer 25

Type 2 cells release lipid-rich surfactant Lowers the surface tension of the fluid lining the alveoli An increase in surface area on lung inflation would ordinarily increase surface tension and cause lung collapse Surfactant prevents this (Laplace’s Law) by decreasing the distending Pressure.

Answer 26

Surfactant produced from 26 weeks prenatally so premature infants are vulnerable to collapsed lung (respiratory distress syndrome-RDS) Cortisol treatment for mother in labour can help stimulate surfactant production Infants treated with O2 to resolve RDS.

Answer 27

Type 1 alveolar cells Alveolar basement membrane Interstitial space: elastic fibres Capillary basement membrane Capillary endothelium

Answer 28

Anything that affects diffusion will affect gas exchange; factors that affect diffusion include: Surface area Diffusion distance (i.e. thickness of membrane) Diffusion gradient Fick’s law

Answer 29

Very large in healthy lungs (spherical structures have very large surface area (80-100 square metres) Inflation increases the available surface area for exchange Multiple small alveoli increases surface area Larger spaces/cavities have smaller surface areas

Answer 30

Patients have degraded alveolar walls. This results in a smaller surface area for gas exchange

Answer 31

Normally very short in healthy lungs (0.4 to 2.0 mm, can be0.6µm) Increased if there is fluid in the lungs (e.g. in pneumonia) or mucus in the lungs (e.g. cystic fibrosis) If alveolar PO2 is low or the diffusion resistance is high, capillary PO2 may not reach equilibrium with alveolar PO2. ie There is not enough difference between the 2 to allow diffusion

Answer 32

Fick’s law and means that diffusion of gas is slow if the diffusion thickness increases.

Answer 33

Diffusion is proportional to surface area and concentration difference. It is inversely proportional to diffusion distance. It requires there to be a difference in pp across the membrane means that the rate of diffusion will decrease if area of diffusion decreases and/or the diffusion distance increases.

Answer 34

R = D x A x (triangle) p/t ------ R = rate of diffusion D = diffusion constant for gas ie (triangle) O2 A = surface area (70 m2 in human lungs) p = differences in partial pressures across the membrane t = thickness of respiratory membrane (0.5 - 1.5 mm in human lung)

Answer 35

Gases diffuse from high to low PP Increased by repeated replenishment of air with high PO2 and low PCO2 (breathing) Decreased if ventilation or blood flow are reduced e.g. lung blood flow reduced due to pulmonary embolism

Answer 36

The rate of oxygen uptake depends on the rate at which it is supplied (ventilation), and the rate at which it is removed (perfusion). Ventilation: amount of air reaching the alveoli/minute Perfusion: amount of blood reaching the alveoli/minute V/P ratio determines blood O2 and CO2 concentration Mismatch leads to respiratory failure

Answer 37

Due to gravity, blood flow is greater at the base than at the apex of the lungs Apex of the lungs has a higher V/Q ratio There is more ventilation here , and V/Q = α when there is ventilation and no perfusion. Base has lower V/Q as gravity means there is more blood at the base (higher perfusion) V/Q can be 0 if there is perfusion but no ventilation.

Answer 38

V/Q = Ratio : Average 0.8 for the whole lung Higher at Apex (>0.8) Due to gravity and height above or below heart Means more perfusion than ventilation (<0.8 for base) Disease alters V/Q ratio

Answer 39

- Cardiac output - Pulmonary vascular resistance

Answer 40

Decreased ventilation in lung No effect on blood flow Low arterial PO2 Associated increase in PCO2. Chronic bronchitis, asthma, acute oedema

Answer 41

Increases PO2 and dead space in lungs (high ventilation) Decrease in arterial O2 saturation Seen in emphysema where there is lots of ventilation but small area for blood exchange Tachypnea

Answer 42

the environment required for life and metabolism. Includes temperature, pH, glucose, gas levels. It is the blood plasma and interstitial fluid.

Answer 43

Cardiovascular system is essential for maintaining this environment as it helps to regulate gas exchange, temperature regulation etc

Answer 44

- to maintain the correct conditions for cellular function. EG prevent cellular and protein damage - Damage to proteins is often irreversible (think of fried eggs) and damage could affect: - Enzymes, cell surface receptors, transporters etc - Can result in cell death

Answer 45

By red blood cells Haemoglobin is the protein found in RBC is responsible for gas exchange (1g Hb = 1.34mls O2)

Answer 46

- Fetal - Adult A - Adult A2 Some forms are responsible for sickle cell anaemia Males* often have more haemoglobin (linked to menstruation and iron levels)

Answer 47

A tetramer (4) globin polypeptide chains: a pair of a-like chains and a pair of b-like chains

Answer 48

Oxyhaemoglobin

Answer 49

α2β2; (Alpha2beta2)

Answer 50

the number of oxygen molecules bound e.g. if 2 molecules of oxygen are bound to one Hb molecule, it is 50% saturated.

Answer 51

The relationship between percentage saturation of Hb with oxygen, and partial pressure of oxygen

Answer 52

in alveoli, PO2 is about 104mmHg, which means that Hb is almost 100% saturated. - It has a high AFFINITY for oxygen In systemic veins, the partial pressure of oxygen is about 40mmHg, and Hb is around 77% saturated - It has a low affinity for oxygen This dissociation curve can be shifted to the left or right. Eg low temperature shifts it to the left. High temp to the right.

Answer 53

Blood carries carbon dioxide, When blood PCO2 is high, the affinity of Hb for oxygen falls The curve shifts to the rights, and most oxygen is released Meaning haemoglobin is linked to amount of oxygen available

Answer 54

High = holding O2 and taking into blood Low = releasing into the tissues

Answer 55

When there is an increase in H+, blood acidity increases. Blood acidity has consequences for health and can result in cardiovascular problems, cellular problems and death

Answer 56

- Acidity within the diet (ketone (high protein)) > can cause ketoacidosis (diabetes) (symptoms include acidic smelling breath) - Acidity with CO2

Answer 57

In the lungs: O2 moves along the gradient into the bloodstream and is bound by haemoglobin In tissues: myoglobin (increased affinity for O2 in exercise) has a higher affinity for oxygen so oxygen moves from the blood into the tissues. O2 is then released into the cells

Answer 58

Carbon dioxide is a waste product of metabolism Carried to the lungs to be removed Some Carbon dioxide is dissolved in blood plasma (8%) 20% binds to amines in Hb to form carbaminohaemoglobin Rest (72%) reacts with water in the cytoplasm of the RBC

Answer 59

7.35 to 7.45. The range is maintained by: Buffers H + loss in urine by the kidney Breathing out CO2

Answer 60

pH can change structures like DNA pH changes can damage enzymes involved in metabolism pH changes the amount of oxygen carried by blood (decrease).

Answer 61

Reversible chemical reaction that can absorb or release hydrogen ions (H+) in response to changes in the system = Bicarbonate buffer system If hydrogen ion concentration is kept constant, pH is kept constant If pH decreases (hydrogen ion level rises), it combines with bicarbonate to form carbonic acid. If pH increase, then carbonic acid dissociates to release more H+

Answer 62

CO2 mixes with water in blood to form carbonic acid (H2CO3) - Inc metabolism means more carbonic acid - More carbonic acid = more breakdown into H and bicarbonate (dec in pH) - Dec in pH detected by chemoreceptors (located in the heart, carotid artery, medulla) - Stimulation of ventilation to get rid of excess CO2

Answer 63

Blood CO2 level (and acidity)

Answer 64

- Dissolved CO2 (PCO2) - pH (eg bicarbonate ions) - Peripheral chemoreceptors located in the carotid and aortic bodies (central chemoreceptors = cardiovascular control centre)

Answer 65

Healthy lungs are complaint to allow increase in surface area. The Hering-Breuer Inflation reflex prevents over-inflation. - Normal breathing in infants (controls breathing all the time) - Only extreme exercise in adults (not triggered to work all the time, just to stop over-inflation)

Answer 66

When activated by lung stretch, slowly adapting stretch receptors fire with increasing frequency. High receptor activity inhibits further inflation, and expiration begins. AKA the inspiratory off-switch

Answer 67

- Increase/decrease H+ - Chemoreceptors in carotid body detect change - Impulse delivered to respiratory control centre (medulla) - Impulse sent to respiratory muscle - Change to frequency and depth of breathing - Stimulus reduced

Answer 68

Movement (exercise)

Answer 69

Throughout airways and lungs (can stimulate coughing and sneezine)

Answer 70

Over-inflation

Answer 71

Control speech or anxiety (there is also pain and emotional stimuli)

Answer 72

Chemoreceptors

Answer 73

There is a degree of compensation which may hide underlying conditions such as acidosis or alkalosis. Respiratory disorders: - Result in pH change - Can stimulate change in breathing to alter CO2 levels Metabolic disorders: - Slower process as it involves a change in kidney function - Change in pH stimulates increase in bicarbonate resorption and synthesis and in breathing!

Week 24 Flashcards

(98 cards)