4/12 Lecture E1

Question 1

Approximately how many alveoli are in each lung?

Answer 1

150 million

Question 2

What type of cells make up 95% of alveoli surface area?

Answer 2

Squamous (type 1) alveolar cells

Question 3

What type of cells make up 5% of alveolar surface?

Answer 3

Round to cuboidal cells (type II)

Question 4

What is the role of type II alveolar cells?

Answer 4

repair the alveolar epithelium when type I cells are damaged.

Question 5

What do type II cells secrete and why?

Answer 5

pulmonary surfactant: a mix of phospholipids and proteins that coats the alveoli and prevents them from collapsing during exhalation.

Question 6

What is the most numerous of all cells in the lung?

Answer 6

Alveolar macrophages (dust cells)

Question 7

What do alveolar macrophages do?

Answer 7

wander lumens and keep alveoli free from debris by phagocytizing dust particles

Question 8

What separates alveolar air from blood?

Answer 8

respiratory membrane

Question 9

What does the respiratory membrane consist of?

Answer 9

squamous alveolar cells, endothelial cells of blood capillary, and their shared basement membrane

Question 10

What is the membrane that closely covers the lungs?

Answer 10

visceral pleura

Question 11

What adheres to the mediastinum, inner surface of the rib cage and the superior surface of the diaphragm?

Answer 11

Parietal pleura

Question 12

What is the function of the pleurae and pleural fluid?

Answer 12

1) reduce friction
2) create pressure gradient: assists lung inflation
3) compartmentalization: prevents the spread of infection

Question 13

What does the diaphragm do?

Answer 13

Prime mover of respiration: contraction pulls air into the lungs, relaxation bulges the muscle and compresses the lungs and expelling the air.

Question 14

What is the purpose of internal and external intercostal muscles?

Answer 14

synergists to diaphragm. stiffen the thoracic cage during respiration. Prevents rib cage from caving inward when diaphragm descends. Add about 1/3 of the air that ventilates the lungs

Question 15

what do the scalenes do?

Answer 15

synergist to diaphragm, fix or elevate ribs 1 and 2

Question 16

What does muscle relaxation during normal respiration do?

Answer 16

recoils structures and results in airflow out of the lungs.

Question 17

During forced expiration, what does the rectus abdominis do?

Answer 17

pulls down on sternum and ribs

Question 18

What causes increased thoracic pressure?

Answer 18

increased abdominal pressure pushing viscera up against diaphragm. This forces air out.

Question 19

Automatic, unconscious cycle of breathing is controlled by what?

Answer 19

three hairs of respiratory centers in the reticular formation of the medulla oblongata and the pons

Question 20

What are the two respiratory groups in the MEDULLA?

Answer 20

Ventral respiratory group and the Dorsal respiratory group

Question 21

What is another word for quiet unlabored breathing?

Answer 21

eupnea

Question 22

What is the primary generator of the respiratory rhythm?

Answer 22

Ventral respiratory group

Question 23

What nerve do inspiratory neurons fire to the diaphragm through and for how long?

Answer 23

Phrenic nerve, two seconds

Question 24

how long do expiratory neurons fire in eupnea?

Answer 24

3 seconds

Question 25

What is the respiratory rhythm produced by the VRG?

Answer 25

12 breaths per minute

Question 26

which respiratory network in the medulla modifies the rate and depth of breathing?

Answer 26

Dorsal respiratory group

Question 27

What is the respiratory network in the pons?

Answer 27

Pontine respiratory group

Question 28

What does the pontine respiratory group do?

Answer 28

1) modifies rhythm of the VRG by outputs to both the VRG and DRG 2) adapts breathing to special circumstances

Question 29

What happens during hyperventilation?

Answer 29

1) CO2 levels drop and pH rises causing cerebral arteries to constrict, reducing cerebral perfusion

Question 30

What are central chemoreceptors?

Answer 30

brainstem neurons that respond to changes in pH of cerebrospinal fluid

Question 31

What does the pH of cerebrospinal fluid reflect?

Answer 31

CO2 level in the blood

Question 32

Where are peripheral chemoreceptors located?

Answer 32

carotid and aortic bodies of the large arteries above the heart

Question 33

What do peripheral chemoreceptors respond to?

Answer 33

O2, CO2, and pH of the blood

Question 34

Where are stretch receptors found?

Answer 34

smooth muscles of bronchi and bronchioles, and in the visceral pleura

Question 35

What do stretch receptors respond to and which nerve do they use?

Answer 35

inflation of the lungs via the vagus nerve

Question 36

What is the inflation reflex also called?

Answer 36

Hering-Breuer reflex

Question 37

What is the inflation reflex triggered by?

Answer 37

excessive inflation

Question 38

What does the inflation reflex do?

Answer 38

its a reflective reflex that inhibits inspiratory neurons and stops inspiration.

Question 39

What are the irritant receptors?

Answer 39

nerve endings amid the epithelial cells of the airway

Question 40

What do irritant receptors respond to?

Answer 40

smoke, dust, pollen, chemical fumes, cold air and excess mucous

Question 41

What do irritant receptors trigger?

Answer 41

Protective reflexes such as bronchoconstriction, shallower breathing, breath-holding (apnea), or coughing

Question 42

Where does voluntary control of breathing originate?

Answer 42

in the motor cortex of frontal lobe of the cerebrum.

Question 43

How does voluntary control happen?

Answer 43

Impulses are send from the motor cortex of the frontal lobe of the cerebrum down corticospinal tracts to respiratory neurons in spinal cord, bypassing brainstem

Question 44

What is the limit to voluntary control?

Answer 44

The breaking point is when CO2 levels rise to a point where automatic controls override one's will.

Question 45

True or false: respiratory airflow is governed by the same principles of flow, pressure, and resistance as blood flow.

Answer 45

True

Question 46

What are the principles of respiratory airflow?

Answer 46

1) the flow of a fluid is directly proportional to the pressure difference between two points 2) the flow of a fluid is inversely proportional to the resistance.

Question 47

What type of pressure drives respiration?

Answer 47

atmospheric pressure

Question 48

What is atmospheric pressure?

Answer 48

the weight of the air above us

Question 49

What is atmospheric pressure at sea level?

Answer 49

760 mmHg at sea level or 1 atm. Pressure is lower at hight elevations

Question 50

What is Boyle's Law?

Answer 50

at a constant temperature, the pressure of a given quantity of gas is inversely proportional to its volume

Question 51

If the lungs contain a quantity of a gas and the lung volume increases, their internal pressure (intrapulmonary pressure) ___.

Answer 51

falls

Question 52

if the pressure falls below atmospheric pressure, air moves ___ the lungs.

Answer 52

into

Question 53

If the lung volume decreases, intrapulmonary pressure ____.

Answer 53

rises

Question 54

if the pressure of the lungs rises above atmospheric pressure, air moves ___ of the lungs.

Answer 54

out

Question 55

What is the unit of pressure used by respiratory physiologists?

Answer 55

cm H2O

Question 56

which is more sensitive: mmHg or cm H2O?

Answer 56

cm H2O

Question 57

What is intrapleural pressure?

Answer 57

the slightly negative pressure that exists between the two pleural layers

Question 58

what causes intrapleural pressure?

Answer 58

the recoil of lung tissue and tissues of thoracic cage causes lungs and chest wall to be pulling in opposite directions. the small space between the parietal and visceral pleura is filled with watery fluid, and they cling together. A negative 5 sm H2O pressure results.

Question 59

What happens to the alveoli during inspiration?

Answer 59

They stretch within the lungs

Question 60

As the thoracic cage increases in volume, what happens to the internal pressure?

Answer 60

The pressure drops and air flows in.

Question 61

What is Charles' Law?

Answer 61

volume of a gas is directly proportional to its absolute temperature

Question 62

Specific to anatomy, what is Charles' Law?

Answer 62

warming of the air expands the lungs. The air is warmed as it moves through the tubing to the alveoli.

Question 63

How is relaxed expiration mainly achieved?

Answer 63

Elastic recoil of the thoracic cage

Question 64

What is the intrapulmonary pressure during relaxed expiration?

Answer 64

about 1 cm H2O

Question 65

Why does air flow out during relaxed expiration?

Answer 65

Air flows down the pressure gradient

Question 66

During forced breathing, what happens to the intrapulmonary pressure?

Answer 66

Accessory muscles raise the pressure as high as +40 cm H2O

Question 67

What is Pneumothorax?

Answer 67

The presence of air in pleural cavity

Question 68

What does a pneumothorax result in?

Answer 68

loss of negative intrapleural pressure allows lungs to recoil and collapse

Question 69

What is atelectasis?

Answer 69

Collapse of part or all of a lung

Question 70

What can atelectasis result from?

Answer 70

An airway obstruction as blood absorbs gases from blood

Question 71

What two factors influence airway resistance?

Answer 71

1) bronchiole diameter | 2) pulmonary compliance

Question 72

What stimulates bronchodilation?

Answer 72

Epinephrine and sympathetics stimulate dilation

Question 73

What does bronchodilation result in?

Answer 73

increased airflow

Question 74

What stimulates bronchoconstriction?

Answer 74

Histamine, parasympathetic nerves, cold air, and chemical irritants

Question 75

What does bronchoconstriction result in?

Answer 75

decreased airflow

Question 76

What does extreme bronchoconstriction result in and what is a potential cause?

Answer 76

Extreme constriction can cause suffocation. This can be caused by anaphylactic shock of asthma

Question 77

What is pulmonary compliance?

Answer 77

Ease with which the lungs can expand

Question 78

What can reduce pulmonary compliance?

Answer 78

degenerative lung diseases in which the lungs are stiffened by scar tissue

Question 79

What is compliance limited by?

Answer 79

the surface tension of the water film inside alveoli

Question 80

What causes infant respiratory distress syndrome?

Answer 80

premature babies lacking surfactant

Question 81

RX for infant respiratory distress syndrome

Answer 81

artificial surfactant until they can make their own