Digestive System 1

Question 1

What are the 6 Main Digestive Concepts?

Answer 1

Ingestion
Motility
Secretion
Digestion
Absorption
Defecation

Question 2

What are Ingestion and Motility?

Answer 2

Ingestion – entry to mouth
Motility – movement – mixing/propulsion

Question 3

What is Secretion

Answer 3

Secretion – contributions – release of water/enzymes / environmental factors

Question 4

What are Digestion, Absorption and Defacation?

Answer 4

Digestion: Mechanical and Chemical breakdown
Absorption: entry to body.
Defecation: elimination from body.

Question 5

What is the GI Tract?

Answer 5

Gastrointestinal (GI) tract-
muscular tube; from mouth to anus

Question 6

What are the Functions of the GI Tract?

(4)

Answer 6

• Material to build and fuel body.
• Ingestion with breakdown.
• Absorption to internal environment.
• Elimination of remaining material plus metabolic end products and wastes.

Question 7

What Receptors can Detect Change in the GI Tract?

(3)

Answer 7

Mechanoreceptors: Distension (stretch)
Osmoreceptors: Omolarity
Chemoreceptors: Specific concentrations and acidity

Question 8

What is the Respone of Smooth Muscle Cells to Gastrointestinal regulation?

Answer 8

Smooth muscle cells – circular and longitudinal muscle layer
contractions

Question 9

What is the Respone of Enteroendocrine Cells Gastrointestinal regulation?

Answer 9

Enteroendocrine cells – hormonal secretions

Question 10

What is the Respone of Exocrine cells to Gastrointestinal regulation?

Answer 10

Exocrine cells – enzyme and environmental secretions

Question 11

What is the Respone of Mucous cells to Gastrointestinal regulation?

Answer 11

Mucous cells – mucus secretions

Question 12

Afferent information sent to CNS from receptors (3)

Answer 12

Somatic sensory – muscles.
Visceral sensory – organs.
Special sensory – eyes, ears, etc

Question 13

Efferent information sent to effectors from CNS (3)

Answer 13

Somatic motor – muscles.

Autonomic motor (or autonomic nervous system; ANS): sympathetic, parasympathetic, enteric – variable targets.

Enteric –GI tract’s own local neural control; more neurons than spinal cord.

Question 14

Afferent vs Efferent Neural Divisons?

Answer 14

Question 15

What is the Enteric nerve plexuses?
What are the 2 Main ones?

Answer 15

Enteric nerve plexuses are intricate networks of neurons that are located in the walls of the gastrointestinal (GI) tract:
- Myenteric
- Submucosal

Question 16

What type of communication exists between the Enteric nerve plexuses?

(3)

Answer 16

• Within plexus and between plexuses.
• Receptors to plexuses
• CNS to plexuses

Question 17

What is the Myenteric Plexus?

Answer 17

This plexus is situated between the circular and longitudinal muscle layers of the GI tract. It primarily controls muscle contractions and is involved in regulating the motility of the digestive system

Question 18

What is the Submucosal Plexus?

Answer 18

This plexus is located in the submucosa of the GI tract, beneath the mucous membrane, especially Epithelial Cells. It is responsible for regulating secretions from the mucosal glands, blood flow, and absorption in the intestine

Question 19

What are the Short reflexes of the Enteric nerve plexuses?

Answer 19

Short reflexes (intrinsic to GI tract; enteric)

• Within GI tract.
• Stimuli – receptors – plexus – effector – response

Question 20

What are the Long reflexes of the Enteric nerve plexuses?

Answer 20

Long reflexes (extrinsic to GI tract; CNS)

• Extending outside GI tract and adds to enteric path:
• Afferent – receptors to CNS.
• Efferent autonomic (sympathetic and
  parasympathetic) – CNS to plexuses

Question 21

Short and Long Responses Visual:

Answer 21

Question 22

What are Enteroendocrine cells?

Location, Structure, function, Target Areas

Answer 22

Location: Mainly stomach and small intestine.

Structure: have one surface that is exposed to the lumen of the GI tract, allowing them to detect and respond to stimuli encountered in the digestive contents

Function: When stimulated, opposite cell surface from GI tract lumen releases hormone into blood, can be inhibitory or excitatory

Target Area: Can have multiple target areas

Question 23

What are the Key Hormones released by the Enteroendocrine cells?

Answer 23

• Gastrin
• Secretin
• Cholecystokinin (CCK)
• Somatostatin

Question 24

What is a Chemical messenger

Answer 24

Chemical messenger – hormone, neurotransmitter,
paracrine substance, autocrine substance.

• Chemical messenger is released and will bond a receptor on a target.
• Target will generate a response to the binding of the receptor.
• Targets can be close to release site or over distance.

Question 25

What is a Cephalic stimuli?

Answer 25

signal to salivary center in medulla oblongata

Question 26

What is the Parasympathetic Response of Cephalic stimuli?

2

Answer 26

Basic stimulation – signals salivary glands to provide basic level of salivation (saliva production) to keep tissues moist

Parasympathetic to stomach in preparation for food coming - increases acid secretion and stomach motility

Question 27

Parasympathetic

Cephalic Stimuli Flow Chart:

Answer 27

Question 28

What is the Sympathetic Response of Cephalic stimuli?

Answer 28

Sympathetic stimulation:

• Increased stimulation – signals salivary glands to decrease salivation.
• Alters volume and composition.
• Dry mouth feel

Question 29

Sympathetic

Cephalic Stimuli Flow Chart:

Answer 29