PNB 2265: Exam 3 Questions And
Answers With Correct Solutions
100% Update 2025/ 2026
Is the increased ventilation that occurs during exercise due to changes in blood
chemicals? - CORRECT ANSWES -- No, right after exercise begins, arterial PO2 and
PCO2 do not immediately change in concentration
Factors stimulating abrupt increase of ventilation at onset of exercise - CORRECT
ANSWES -- -Reflex input from proprioceptors
-Input from motor cortex
Brainstem respiratory control centers - CORRECT ANSWES -- Responsible for:
-Respiratory rhythm generation
-Activation of inspiratory and expiratory nerves and muscles
-Changes in alveolar ventilation caused by changes in arterial blood gas partial
pressures
DRG - CORRECT ANSWES -- Receives all sensory input, mostly sensory input from
chemoreceptors in blood and brain (CSF), sends input to inspiratory center (VRG)
How do we regulate breathing? - CORRECT ANSWES -- -Increased ventilation by
increasing rate and depth of breathing
-Regulated by chemical factors in blood (CO2, pH (H+ levels), O2)
-CO2 (and pH) are by far the most important regulatory chemicals
What are the most important regulatory chemicals of breathing? - CORRECT ANSWES
-- CO2 and pH
How do we increase ventilation? - CORRECT ANSWES -- By increasing RATE and
DEPTH of breathing
When blood CO2 rises: - CORRECT ANSWES -- pH decreases
How do we detect changes in chemical factors? - CORRECT ANSWES -- Peripheral
chemoreceptors and central chemoreceptors
,Peripheral chemoreceptors - CORRECT ANSWES -- Receptors in carotid and aortic
bodies, sensitive to PCO2 (PCO2 and pH), CO2 is immediate control
Central chemoreceptors - CORRECT ANSWES -- Sensitive to pH in CSF (when blood
CO2 rises, pH decreases)
Ventilation changes associated with changes in plasma variables - CORRECT
ANSWES -- As CO2 increases, almost linear relationship with minute ventilation
Oxygen decrease drives increase in ventilation after large decrease in PO2, BIG
increase in oxygen levels before chemoreceptors for oxygen are activated
Control by PO2 - CORRECT ANSWES -- Peripheral chemoreceptors STIMULATED by
decrease O2 of systemic ARTERIAL blood (must be a large decrease)
-Effect: stimulation (chemoreceptors project to DRG, which then projects to VRG) ->
increased ventilation
Control by PCO2 (and pH) - CORRECT ANSWES -- -Peripheral chemoreceptors sense
CO2 and pH
-Central chemoreceptors sense pH (due to increase of CO2 in brain CSF)
-Effect: increased ventilation
Stimulatory factors of ventilation - CORRECT ANSWES -- Increased acidity, increased
CO2, decreased oxygen
Summary of major chemical inputs that stimulate ventilation - CORRECT ANSWES --
See diagram
GI functions - CORRECT ANSWES -- Motility, secretion, absorption
Integrated meal response - CORRECT ANSWES -- Cephalic/esophageal
Gastric
Intestinal
Colonic
Gross anatomy of digestive system - CORRECT ANSWES -- Alimentary canal:
-Mouth
-Esophagus
-Stomach
-Intestines: small
-Intestines large
-Rectum
Accessory organs:
, -Salivary glands
-Liver
-Pancreas
-Gallbladder
Serous peritoneum - CORRECT ANSWES -- Serosa lining the abdominal cavity and
covering its organs, made up of parietal peritoneum, peritoneal fluid, and visceral
peritoneum
Parietal peritoneum - CORRECT ANSWES -- Lines walls of abdominal cavity
Visceral peritoneum - CORRECT ANSWES -- Covers the surface of digestive organs
What is often stored between folds of peritoneum - CORRECT ANSWES -- Visceral fat
Omentum - CORRECT ANSWES -- An extension of the peritoneum attached to the
stomach and connecting it with other abdominal organs, major place of fat storage
History of GI tract - CORRECT ANSWES -- There is a conserved structure throughout
the GI tract (with some modifications)
-Serosa
-Muscularis
-Submucosa
-Mucosa (forms lumen that comes in contact with tube)
Serosa - CORRECT ANSWES -- Outermost connective tissue layer, serves as structure
and protection, connective with blood vessels
Also known as adventitia
Muscularis externa - CORRECT ANSWES -- Smooth muscle layer, consists of two
layers, outer "longitudinal" layer that changes length of GI tract and inner "circular" layer
that changes the radius of the GI tract, myenteric plexus in between two muscle layers
2 layers of muscularis externa - CORRECT ANSWES -- Outer longitudinal layer:
changes length of GI tract
Inner circular layer: changes radius of GI tract
Myenteric plexus - CORRECT ANSWES -- Major site of innervation in GI tract, nervous
tissue layer located between two muscle layers of the muscularis externa, majority is
PARASYMPATHETIC, neuronal signal in both directions, permeating from inside lumen
regarding what types of food/molecules are present, how much lumen stretched, etc.
and from higher brain centers to signal to cells to produce secretions, contract smooth
muscle, etc.
Answers With Correct Solutions
100% Update 2025/ 2026
Is the increased ventilation that occurs during exercise due to changes in blood
chemicals? - CORRECT ANSWES -- No, right after exercise begins, arterial PO2 and
PCO2 do not immediately change in concentration
Factors stimulating abrupt increase of ventilation at onset of exercise - CORRECT
ANSWES -- -Reflex input from proprioceptors
-Input from motor cortex
Brainstem respiratory control centers - CORRECT ANSWES -- Responsible for:
-Respiratory rhythm generation
-Activation of inspiratory and expiratory nerves and muscles
-Changes in alveolar ventilation caused by changes in arterial blood gas partial
pressures
DRG - CORRECT ANSWES -- Receives all sensory input, mostly sensory input from
chemoreceptors in blood and brain (CSF), sends input to inspiratory center (VRG)
How do we regulate breathing? - CORRECT ANSWES -- -Increased ventilation by
increasing rate and depth of breathing
-Regulated by chemical factors in blood (CO2, pH (H+ levels), O2)
-CO2 (and pH) are by far the most important regulatory chemicals
What are the most important regulatory chemicals of breathing? - CORRECT ANSWES
-- CO2 and pH
How do we increase ventilation? - CORRECT ANSWES -- By increasing RATE and
DEPTH of breathing
When blood CO2 rises: - CORRECT ANSWES -- pH decreases
How do we detect changes in chemical factors? - CORRECT ANSWES -- Peripheral
chemoreceptors and central chemoreceptors
,Peripheral chemoreceptors - CORRECT ANSWES -- Receptors in carotid and aortic
bodies, sensitive to PCO2 (PCO2 and pH), CO2 is immediate control
Central chemoreceptors - CORRECT ANSWES -- Sensitive to pH in CSF (when blood
CO2 rises, pH decreases)
Ventilation changes associated with changes in plasma variables - CORRECT
ANSWES -- As CO2 increases, almost linear relationship with minute ventilation
Oxygen decrease drives increase in ventilation after large decrease in PO2, BIG
increase in oxygen levels before chemoreceptors for oxygen are activated
Control by PO2 - CORRECT ANSWES -- Peripheral chemoreceptors STIMULATED by
decrease O2 of systemic ARTERIAL blood (must be a large decrease)
-Effect: stimulation (chemoreceptors project to DRG, which then projects to VRG) ->
increased ventilation
Control by PCO2 (and pH) - CORRECT ANSWES -- -Peripheral chemoreceptors sense
CO2 and pH
-Central chemoreceptors sense pH (due to increase of CO2 in brain CSF)
-Effect: increased ventilation
Stimulatory factors of ventilation - CORRECT ANSWES -- Increased acidity, increased
CO2, decreased oxygen
Summary of major chemical inputs that stimulate ventilation - CORRECT ANSWES --
See diagram
GI functions - CORRECT ANSWES -- Motility, secretion, absorption
Integrated meal response - CORRECT ANSWES -- Cephalic/esophageal
Gastric
Intestinal
Colonic
Gross anatomy of digestive system - CORRECT ANSWES -- Alimentary canal:
-Mouth
-Esophagus
-Stomach
-Intestines: small
-Intestines large
-Rectum
Accessory organs:
, -Salivary glands
-Liver
-Pancreas
-Gallbladder
Serous peritoneum - CORRECT ANSWES -- Serosa lining the abdominal cavity and
covering its organs, made up of parietal peritoneum, peritoneal fluid, and visceral
peritoneum
Parietal peritoneum - CORRECT ANSWES -- Lines walls of abdominal cavity
Visceral peritoneum - CORRECT ANSWES -- Covers the surface of digestive organs
What is often stored between folds of peritoneum - CORRECT ANSWES -- Visceral fat
Omentum - CORRECT ANSWES -- An extension of the peritoneum attached to the
stomach and connecting it with other abdominal organs, major place of fat storage
History of GI tract - CORRECT ANSWES -- There is a conserved structure throughout
the GI tract (with some modifications)
-Serosa
-Muscularis
-Submucosa
-Mucosa (forms lumen that comes in contact with tube)
Serosa - CORRECT ANSWES -- Outermost connective tissue layer, serves as structure
and protection, connective with blood vessels
Also known as adventitia
Muscularis externa - CORRECT ANSWES -- Smooth muscle layer, consists of two
layers, outer "longitudinal" layer that changes length of GI tract and inner "circular" layer
that changes the radius of the GI tract, myenteric plexus in between two muscle layers
2 layers of muscularis externa - CORRECT ANSWES -- Outer longitudinal layer:
changes length of GI tract
Inner circular layer: changes radius of GI tract
Myenteric plexus - CORRECT ANSWES -- Major site of innervation in GI tract, nervous
tissue layer located between two muscle layers of the muscularis externa, majority is
PARASYMPATHETIC, neuronal signal in both directions, permeating from inside lumen
regarding what types of food/molecules are present, how much lumen stretched, etc.
and from higher brain centers to signal to cells to produce secretions, contract smooth
muscle, etc.
