RS Lec 7

Question 1

rhythm of breathing is established by

Answer 1

CNS

Question 2

breathing is initiated in (general) and by

Answer 2

medulla by specialized neurons

Question 3

breathing is modified by (general)

Answer 3

• higher structures of CNS

- signals from central & peripheral chemoreceptors & mechanoreceptors in lung and chest wall

Question 4

neural networks establish

Answer 4

automatic rhythm of muscle contraction

Question 5

groups of respiratory neurons in brainstem (3)

Answer 5

• pqntine respiratory group
• dorsal respiratory group
• ventral respiratory group (VRG)

Question 6

in VRG, PreBotC generate

Answer 6

excitatory inspiratory rhythmic activity that excite inspiratory muscles via polysynaptic pathway

Question 7

PreBot C stands for

Answer 7

prebotzinger complex

Question 8

PreBotC is in

Answer 8

ventral respiratory group

Question 9

in VRG, pFRG generate

Answer 9

active excitatory expiratory rhythmic activity that excite expiratory muscles via polysynaptic pathway

Question 10

pFRG stands for

Answer 10

parafacial respiratory group

Question 11

pRFG is in

Answer 11

ventral respiratory group

Question 12

Neuronal networks adjust rhythm of breathing to accommodate changes in (4)

Answer 12

• metabolic demands
• varying mechanical conditions (e.g., changing posture)
• non-ventilatory behaviors (e.g., speaking, sniffing, eating)
• pulmonary and non-pulmonary diseases

Question 13

VRG creates

Answer 13

rhythm of breathing

Question 14

PreBötC and pFRG neurons drive activity in … that excites

Answer 14

premotor neurons, which excites motoneurons that activate respiratory muscles

Question 15

neuro-respiratory pathway for diaphragm & ext. intercostal muscles (insp.)

Answer 15

– preBötC→INS premotoneuron (ROSTRAL VRG)→
phrenic & thoracic inspiratory motoneurons (in cervical & thoracic spinal cord)→
DIAPHRAGM (phrenic) & EXT. INTERCOSTAL muscles (thoracic)

Question 16

neuro-respiratory pathway for tongue & upper airway muscles (insp.)

Answer 16

preBötC→
INS premotoneuron (ROSTRAL VRG & parahypoglossal
region, pXII)→
cranial motoneurons (in medulla)→TONGUE & UPPER
AIRWAY MUSCLES

Question 17

neuro-respiratory pathway for int. intercostal &
abdominal muscles (active exp.)

Answer 17

pFRG→ EXP premotoneurons (caudal VRG)→
thoracic & lumbar expiratory motoneurons (in spinal cord)→
INT. INTERCOSTAL (thoracic) & ABDOMINAL MUSCLES (lumbar)

Question 18

activity of preBötC neurons may be depressed by (2)

Answer 18

• drugs
  ex. anesthetics (propofol)
• pain killers (opioids-fentanyl).

Question 19

Depression of preBötC neurons activity leads to

Answer 19

• respiratory depression

- eventually death for respiratory arrest.

Question 20

Naloxone does what?

Answer 20

reverse opioids effects

Question 21

Hypoxia

Answer 21

low PO2

Question 22

hypercapnia

Answer 22

high PCO2

Question 23

acidosis

Answer 23

low pH in blood

Question 24

Chemoreceptors are

Answer 24

• specialized structures that sense changes in

PO2,PCO2 and pH

Question 25

two types of chemoreceptors

Answer 25

-peripheral and central chemoreceptors

Question 26

carotid + aortic bodies are

Answer 26

peripheral chemoreceptors

Question 27

carotid + aortic sinuses are

Answer 27

baroreceptors

Question 28

Carotid and aortic bodies sense

Answer 28

HYPOXIA (low arterial PO2) but are also sensitive to pH

Question 29

carotid bodies summary (5)

Answer 29

• extremely small
• chemosensitive
• highly vascularized
• high metabolic rate
• neuron like qualities

Question 30

PO2, PCO2, and pH in the carotid body capillaries

Answer 30

the same as in the systemic arteries

Question 31

two types of cells in carotid bodies

Answer 31

• type I/ glomus cells.

- type II/ sustentacular cells

Question 32

Type II/sustentacular cells

Answer 32

-act as support in the CB

Question 33

type I/glomus cells

Answer 33

chemosensitive cells of CB

Question 34

neuron-like characteristics

Answer 34

• Glomus cells have voltage-gated ion channels.
  • Depolarization triggers action potentials (their firing rate
  increases).
  • Glomus cells have numerous intracellular vesicles containing neurotransmitters— acetylcholine, dopamine, norepinephrine, substance P, and met-enkephalin.
  • Stimulation causes the release of these neurotransmitters and
  controls the firing of the sensory nerve endings.

Question 35

A decrease in arterial PO2 is the primary stimulus for

Answer 35

the peripheral chemoreceptors

Question 36

Glomus cells display an increase in firing rate with

Answer 36

lowering of PO2

Question 37

Glomus cells are also sensitive to changes in

Answer 37

• PCO2 and pH (increase response to hypoxia)

Question 38

Stimulation of peripheral chemoreceptors occurs at arterial PO2 values below

Answer 38

60mmHg

Question 39

Peripheral chemoreceptors activate

Answer 39

dorsal and ventral respiratory group neurons in the medulla
– ↑respiratory rate
– ↑ tidal volume

Question 40

Central chemoreceptors are

Answer 40

specialized neurons located close to the ventral surface of the medulla (close contact with blood vessels and cerebrospinal fluid).

Question 41

•Other chemosensitive sites are in

Answer 41

the medullary raphe, hypothalamus

Question 42

Central chemoreceptors are responsible for

Answer 42

70% of response to hypercapnia by changes at the level of

dorsal and ventral respiratory groups that change ventilation

Question 43

H+ stimulates

Answer 43

mostly peripheral chemoreceptors because H+ does not

cross easily blood brain barrier (as CO2 does)