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Biol125 - Human Physiology > Week 4 > Flashcards

Week 4 Flashcards

(72 cards)

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1
Q

What is an ecg ? What does this result in ?

A

Electrical trace of the action potentials in all the heart muscle fibres
A wave of electrical activity passing through the heart that can be picked up by electrodes on the chest

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2
Q

What is the ecg wave split into ?

A

P wave - atrial depolarisation
QRS complex - depolarisation of ventricle
T wave - repolarisation of ventricle muscle

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3
Q
A
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4
Q

At rest what is the average number of breaths per minute and the average volume of air breathed in ?

A

12-15 times a minute ( respiratory rate )
500mls of air per breath

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5
Q

What is teh upper part of the respiratory system ?

A

Nose , larynx , pharynx , trachea

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6
Q

What is the lower part of the respiratory system ?

A

Lower Trachea , right main bronchus , lungs

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7
Q

How many lobes does the right and left lung have ?

A

Right - 3 lobes
Left - 2 lobes

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8
Q

What forms from terminal bronchioles ?

A

Respiratory bronchioles

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9
Q
A
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10
Q

Describe the branching of the bronchial tree ?

A

Trachea
Main bronchi
Lobar bronchi
Segmental bronchi
Bronchioles
Terminal bronchioles

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11
Q

What does the mucociliary blanket do ?

A

Catches particles 2-5µm, cilia moves them to be swallowed or expectorated : filtration 100ml mucous produced a day

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12
Q

Are cilia and goblet cells present in the lower or upper bronchiole branching ?

A

Upper

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13
Q

What are the structures in the conducting and in the respiratory zone ?

A

Conducting -
Transfer of air into lungs - Nasal cavity
Pharynx
Larynx
Bronchi
Bronchioles
Terminal Bronchioles

Respiratory zone -
Gas exchange between blood and air

Respiratory Bronchioles
Alveolar Ducts
Alveolar Sacs
Alveoli

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14
Q

Why is muscle pain often observed with forceful breathing ?

A

More muscles are used
In quiet breathing there is only the diaphragm , internal and external intercostals are used

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15
Q

Describe how inhalation occurs

A

Diaphragm contracts, external intercostal muscles contract
Chest cavity and lung volume expand
Alveolar pressure drops to 758mmHg
Atmospheric pressure (760mmHg) is now higher than internal pressure
Air is drawn in from high to low pressure

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16
Q

Why is intrapleural pressure always negative ?

A

Helps the lungs to expand and stay inflated

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17
Q

Describe exhalation

A
  1. Diaphragm and external intercostal muscles relax
  2. Lungs spring back (recoil) and chest cavity contracts
  3. Contraction increases alveolar pressure to 762 mmHg
  4. air flows out of lungs towards lower atm pressure
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18
Q

What is Boyle’s law ?

A

Volume of gas varies inversely with pressure
I.e squash it and pressure increases

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19
Q

What is dorsal respiration ?

A

Normal quiet inhalation / exhalation

Active phase is 2 secs , diaphragm and intercostal muscles contract , normal quiet inhalation

Inactive phase ( 3 secs ) diaphragm and intercostal muscles relax , lungs recoil, normal quiet exhalation

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20
Q

What is the addition with ventral respiratory group ?

A

Accessory inhalation muscles contract ( ie scalene pectoralis minor) , forceful breathing

Exhalation : internal intercostal, external oblique, transverse, abdomis, rectus abdominis

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21
Q

What are the other influences on control of breathing

A

Voluntary - communication
Other CNS - emotion + gasping or sobbing
Motor cortex - level of effort in exercise feeds into respiratory control centre ( proprioreceptors )

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22
Q

What is anatomical dead space ?

A

Not all of the air reaches the alveoli, it ventilates the trachea, bronchi , and bronchioles it fills the conducting zone , low / no perfusion low gas exchange

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23
Q

What factors affect pulmonary ventilation ?

A

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 —

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24
Q
A
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25
26
What is tidal volume ?
Amount taken in and exhaled on a normal breath
27
What is inspiratory reserve volume ?
Amount taken in in a deep breath
28
What is expiratory reserve volume ?
Amount exhaled in a forced exhalation
29
What is residual volume ?
Air not exchanged but stays in the lungs to keep inflated
30
What is inspiratory capacity ?
Tidal volume + inspiratory reserve volume
31
What is vital capacity ?
Inspiratory reserve volume + tidal volume + expiratory reserve volume
32
33
What is total lung capacity?
Vital capacity + residual volume
34
What is obstructive disease ?
Air passage is obstructed
35
What is restrictive disease ?
Expansion of lungs restricted ?
36
Describe internal vs external respiration
EXTERNAL RESPIRATION: Oxygen diffuses from alveoli into pulmonary capillaries. Carbon dioxide moves in the opposite direction INTERNAL RESPIRATION: Oxygen diffuses from the systemic capillaries into the tissues, and carbon dioxide in the opposite direction
37
Contact time is critical for gas exchange , how does contact time change during exercise?
Time for diffusion decreases
38
If heart rate inc during exercise , what happens to ventricular filling time ?
Decreased
39
What is partial pressure ? How can this be measured? O2pp at sea level?
Pressure of an individual gas, by multiplying the % gas by the total pressure . 159mmHg
40
How does pO2 change at higher atmospheric pressure ?
It is lower
41
How does the stimulus for inc ventilation change at altitude ?
Altitude - reduction in pO2 Sea level - PCO2 is main influence
42
What does external respiration occur across ?
Respiration membrane ( alveolar wall, blood vessel walls )
43
Why does the alveolar wall have elastic fibres ? Why do they have macrophages (dust cells) ? How many types of alveolar cell are there ?
Movement and stretch Filtration 2 types (pulmonary epithelial cells)
44
Which cells release lipid-rich surfactant ?
Type 2 alveolar cells
45
What is laplace’s law ? How does surfactant help ?
P= 2 x T/r T = wall surface tension. R = radius Lowers surface tension, it decreases distending pressure
46
When is surfactant produced from? Who is vulnerable and to what ? What treatment can help mother in labour ? What can infants be treated with ?
26 weeks post-natally Premature infants to collapsed lung (respiratory distress syndrome-RDS) Cortisol O2
47
What cells is the respiratory membrane composed of ?
Type 1 alveolar cells Alveolar basement membrane Interstitial space : elastic fibres Capillary basement membrane Capillary endothelium
48
What factors affect GE?
Surface area Diffusion distance (i.e. thickness of membrane) Diffusion gradient Fick’s law
49
Why do we have many small alveoli ?
Increase SA
50
What increases diffusion distance ? What is normal diffusion distance in a healthy lung ?
Fluid (pneumonia e.g) Mucus ( cystic fibrosis )
51
What is Ficks law?
R= D x A x delta p/t R = rate of diffusion D = diffusion constant for gas ie 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)
52
What does the rate of oxygen uptake depend on ?
Ventilation - rate it is supplied Perfusion - rate at which it is removed
53
Does the Apex or the base have a higher V/Q ratio ?
Apex is higher - more ventilation Base is lower - more blood at base
54
What is perfusion affected by ?
Cardiac output Pulmonary vascular resistance
55
When is V/Q decreased ? Diseases
Decreased ventilation in lung No effect on blood flow Low arterial PO2 Associated inc in PCO2 Chronic bronchitis, asthma, acute oedema
56
What is increased V/Q?
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 - rapid shallowing breathing
57
58
Which sex has more haemoglobin generally ?
Males - linked to menstruation and iron levels
59
What does adult haemoglobin (HbA) have the structure of ?
A2B2
60
When blood PCO2 is high, what happens to the affinity of Hb for oxygen ?
The curve shifts to the right, and more oxygen is released
61
What can blood acidity result in ? In diabetic patients ?
Cardiovascular problems, cellular problems, and death Diabetic ketoacidosis - pear drop smelling breath
62
Why is myoglobin having a higher affinity for oxygen beneficial ?
Oxygen moves from haemoglobin to myoglobin in the tissues
63
How much carbon dioxide is dissolved in the blood plasma ? What percentage binds to amines in Hb to form carbaminohaemoglobin ? The rest ?
8% 20% Reacts with water in the cytoplasm of the RBC
64
What is the pH range of arterial blood ? What is the range maintained by ?
7.35-7.45 Buffers H+ loss in urine by kidney Breathing out CO2
65
What is the acid base buffer system ?
Reversible chemical reaction that can absorb or release hydrogen ions (H+) in response to changes in the system = Bicarbonate buffer system
66
In the blood what does CO2 and water form ? How does metabolism affect this ? What does more carbonic acid mean ?
Carbonic acid ( H2CO3) More carbonic acid More breakdown into hydrogen and bicarbonate (decrease in pH)
67
Which receptor detects pH changes ? What does stimulation of ventilation do ?
Chemoreceptors Get rid of excess CO2 - ventilation stimulation is directly related to blood CO2 level
68
Where are peripheral chemoreceptors found ? Where are central chemoreceptors found ?
Carotid and aortic bodies Cardiovascular control centre
69
Describe the chemical control of breathing
Increased H+ or decrease H+ Chemoreceptors (carotid body ) Respiratory control centre ( medulla ) Respiratory muscles Change to frequency and depth of breathing Stimulus reduced
70
What stops over-inflation of the lungs ?
Hering-Bruer Inflation reflex -Normal breathing in infants -only during extreme exercise in adults Helps us to prevent damage
71
72
What do proprioreceptors do ? What do irritant receptors do ?
Sense movement Stimulate coughing and sneezing

Biol125 - Human Physiology (4 decks)

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