Unit 15: Digestive System II

Question 1

The colon absorbs

Answer 1

Water+electrolytes

Question 2

Stores and Concentrates

Answer 2

Feces

Question 3

Sodium Absorption in the Colon

Answer 3

Absorbed via active transport mechanisms

Question 4

Water Absorption in the Colon

Answer 4

Water follows via osmosis and takes place in the first half of the colon

Question 5

Large Intestine Secretes

Answer 5

Mucous to protect its lining form chemical damage + mechanical damage + lubricate forming feces

Question 6

Ions secreted into the colon

Answer 6

K+

Bicarbonate

Question 7

Small amount of digestion in the colon

Answer 7

Occurs when undigested polysaccharides are metabolized by bacteria into free fatty acids that are absorbed via passive diffusion

Question 8

The bacteria in the colon produced

Answer 8

Gas and vitamin K+ for blood coagulation

Question 9

Careful regulation of _______ and _______ _____ through ______ and ______ mechanisms

Answer 9

motility and hormone secretion through neural and hormonal mechanism

Question 10

Hormonal Mechanisms of Regulation

Answer 10

Release of chemicals from intestinal cells in response to direct mechanical stimulation from food in the stomach + intestine

hormones can be released in response to neural activation

Question 11

Neural Control Mechanisms

Answer 11

Involves the enteric neurons system are divisions of the ANS

Question 12

ANS

Answer 12

SYN

PSYN

Both can influence the digestive tract

Question 13

_ _ _ performs this by altering the ______ of _______ in the _________ nervous system.

Answer 13

ANS performs this by altering the activity of nerves in the enteric nervous system

Question 14

These nerve cells will then affect smooth muscle in the

Answer 14

Walls of the digestive tract

enzyme-secreting cells

endocrine cells

blood vessels of the tract

Question 15

Long reflex loop

Answer 15

Travel from the CNS

Input from the higher brain centers

Stimulus: Sight + Smell of food which is detected by their respective sensors

Signals form the brain are sent through the PSYN to the enteric nervous system to alter the digestive function: enzyme release + gastric motility

Question 16

Short reflex loop

Answer 16

Travels locally within the digestive system

begins by mechanical digestion (stretching) of the digestive tract + chemical changes (pH; osmolarity) w/ in the tract

these changes are detected by sensors of the enteric nervous system that initiate a reflex

reflex activates effector organs

Question 17

Effector organs

Answer 17

Secretory cells

smooth muscle in the walls of the tract

causes the release of enzymes; alters gastric motility

Question 18

PSYN

Answer 18

Increase gastric motility

causes secretion secretion

Production of water saliva

Question 19

SYN

Answer 19

Decreased motility + secretion

Thick viscous saliva + dry mouth

Question 20

Gastrointestinal motility

Answer 20

muscular contraction of the stomach + intestine that mix up food + propel it through the digestive tract

Question 21

Digestion of fatty foods

Answer 21

Long+complex process

if prematurely released from the stomach into the intestine the fats + lipids may not be completely digested

chyme must be released by the stomach in leveled amounts in order to maximize the digestive + absorption process

Question 22

Surrounding the digestive tract

Answer 22

Are specialized smooth muscle cells, interstitial cells

Question 23

Interstitial Cells

Answer 23

spontaneously alter their membrane potential producing Basal electric rhythms

Question 24

BER

Answer 24

Slow waves that travel down the digestive tract

BERs don’t cause the muscles to contract because they don’t reach threshold

Low waves travel from smooth muscle cell to smooth muscle cell through gap junctions

Question 25

Frequency of these BERs

Answer 25

Stomach: 3 waves/min Duodenum: 12 waves/min

Question 26

As long as BER stays below the threshold of the smooth muscle cells

Answer 26

no contraction along the digestive tract

Question 27

If peak of the slow waves reaches threshold

Answer 27

the smooth muscles will contract

Question 28

To Reach threshold

Answer 28

additional stimulus in the form of mechanical, nervous, hormonal input is required additional signals will cause BERs to reach threshold and fire action potentials: causing muscle contraction of the smooth muscle walls

Question 29

contraction travel down the intestine

Answer 29

in a wave-like fashion

Question 30

Hormones of the Intestine

Answer 30

Hormones regulate gastric motility + secretion of enzymes secretion is released in response to the presence of acid in the intestine CCK is released in the presence of fats

Question 31

Cholecystokinin (CCK) is released in the presence of fats

Answer 31

- slows emptying of the stomach - stimulates pancreas to release digestive enzymes - causes gallbladder to contract to release bile

Question 32

Glucose-dependent insulinotropic peptide

Answer 32

secreted in response to glucose + AAs stimulates release of insulin from the pancreas inhibits emptying of the stomach

Question 33

Food

Answer 33

Causes release of hormones

Question 34

Effect of Hormones

Answer 34

Causes release of particular pancreatic enzymes to break down food Decreases motility + slows emptying of the stomach into the intestine Type of food determines the type of hormones released Hormone releases enzymes suited to digest the food

Question 35

Gastric Hormones

Answer 35

- Stomach secretes gastrin - secreted by G-cells located in the antrum of the stomach in response to the presence of proteins + mechanical distention from food + stimulation of PSYN Gastrin causes secretion of HCl

Question 36

HCl is secreted by ____ cells in the stomach

Answer 36

Parietal amount of HCl secreted by these cells varies during the eating-digestive process can be secreted before you start eating

Question 37

Cephalic Stage: Gastric secretion initiated in response to

Answer 37

- sight - smell - taste - chewing - anticipatory response to the act of eating + involves the activation of the enteric nervous system through the long reflex loop

Question 38

Stimulation of the PSYN triggers (stomach)

Answer 38

- PSYN activates the enteric nervous system - parietal cells release HCl - G-cells release gastrin - motility of the stomach increases

Question 39

Gastric Stage

Answer 39

- stomach - gastric phase of acid secretion begins - stimulus - presence of food in the stomach distends the walls - presence of AAs (chemical stimulus) from the breakdown of proteins - Short reflex loop: - enteric nervous system - HCl, gastrin, pepsinogen, increase gastric motility

Question 40

Intestinal Stage

Answer 40

- Intestine - most of digestive + absorptive processes take place here - stimulus - presence of fat, glucose, acidic chyme - decreased motility + inhibit secretions in the stomach - performed by the enteric neurons system - secretin - CCK - glucose-dependent