15. Nutrient Sensing and Uptake

Question 1

TASTE RECEPTORS in the TONGUE send information via which CRANIAL NERVES

Answer 1

FACIAL (VII)
GLOSSOPHARYNGEAL (IX)

Question 2

TASTE RECEPTORS send information via FACIAL and CRANIAL NERVES to the … in the BRAIN STEM

Answer 2

SOLITARY TRACT (NTS)

Question 3

what is the INIATED from the BRAIN STEM NTS from taste receptors activation

Answer 3

VISCERAL REFLEXES TO GUT
- to PREPARE for incoming mean

CEPHALIC RESPONSE
- GASTRIC SECRETIONS

Question 4

what AFFERENT NEURONS send signals from the TONGUE TO NTS - BRAIN STEM

Answer 4

GUSTATORY

Question 5

which EFFERENT NERVES come from NTS (BRAIN STEM)

Answer 5

FACIAL (VII) to salivary glands,
GLOSSOPHARYNGEAL (IX) to salivary glands and oesophagus
VAGUS (X) to gut

Question 6

what does HYPOGLOSSAL NERVE (XII) control

Answer 6

conscious control of TONGUE MUSCLES

Question 7

what does TRIGEMINAL NERVE (V) control

Answer 7

CHEWING

(& sensory to pain)

Question 8

the NUCLEUS of the SOLITARY TRACT PROJECTS to what nucleus

Answer 8

specific GUSTATORY NUCLEUS in the THALAMUS

Question 9

NUCLEUS of the SOLITARY TRACT projects to a specific GUSTATORY NUCLEUS in the THALAMUS and from there to the…

Answer 9

INSULAR CORTEX

Question 10

a lot of our TASTE is based on … SIGNALS

Answer 10

OLFACTORY

(OLFACTORY NERVE I)

Question 11

MAIN OLFACTORY PATHWAY runs from … to …

Answer 11

from OLFACTORY BULB

to PRIMARY OLFACTORY CORTEX (PIRIFORM CORTEX) on the Underside of the TEMPORAL LOBE

Question 12

GUSTATORY PATHEAYS PASS through the…

Answer 12

THALAMUS

Question 13

VISCEREL RESPONSES to taste

Answer 13

• SALIVARY Secretion
• GASTRIC juice
• PANCREATIC Secretion
• GALLBLADDER CONTRACTION

Question 14

GUSTOTOPIC MAP:

Answer 14

TASTE RECEPTORS are EVENLY DISTRIBUTED in tongue

Question 15

LINGUAL EPITHELIAL TASTE RECEPTORS:

TASTE RECEPTOR 1 (T1R) has 3 members.
which are used for UMAMI - taste of L-AMINO ACIDS

Answer 15

T1R1 & T1R3

Question 16

LINGUAL EPITHELIAL TASTE RECEPTORS:

TASTE RECEPTOR 1 (T1R) has 3 members.
which are used for SWEET TASTE?

Answer 16

T1R2 & T1R3

Question 17

LINGUAL EPITHELIAL TASTE RECEPTORS:

TASTE RECEPTOR 2 family (T2Rs) are used for what taste?

Answer 17

BITTER TASTE

Question 18

What type of receptors are TASTE RECEPTORS

Answer 18

G-PROTEIN COUPLED RECEPTORS (GPCR)

Question 19

which G-PROTEIN is coupled with TASTE RECEPTORS

Answer 19

GUSTDUCIN

(from Transducin family of GPCRs)

Question 20

which TASTE RECEPTOR is used for perception of SALTINESS

Answer 20

ENaC - SODIUM CHANNEL

Question 21

what TASTE perception is PKD2LI used for

Answer 21

SOUR TASTE

Question 22

where are there also TASTE CIRCUITS

Answer 22

GUT (INTESTINE)

BILE DUCT
STOMACH
NASAL EPITHELIUM

Question 23

Which GUT CELLS act as NUTRIENT SENSORS

Answer 23

ENTEROENDOCRINE CELLS (EECs)

• central to the chemosensing pathway of the intestinal tract

Question 24

there are AT LEAST … DIFFERENT EEC populations of the GI TRACT PRODUCTING …. HORMONES

Answer 24

at least 12 different EEC

producing >20 HORMONES

Question 25

what are EXPRESSED on the LUMINAL MEMBRANE of EECs

Answer 25

NUTRIENT SENSING GPCRs -> nutrient sensing of these receptors leads to SECRETION of key regulatory GUT HORMONES

Question 26

STOMACH G-CELLS key TASTE RECEPTORS: HORMONE released:

Answer 26

receptors for PEPTIDES and AMINO ACIDS -> GASTRIN release (regulates acid and pepsinogen secretion)

Question 27

STOMACH P/D1 CELLS key TASTE RECEPTORS for: HORMONE released:

Answer 27

receptors for SUGARS (SWEET) & BITTER -> GHRELIN release

Question 28

STOMACH P/D1 CELLS key TASTE RECEPTORS for: HORMONE released:

Answer 28

receptors for SUGARS (SWEET) & BITTER -> GHRELIN release (hunger)

Question 29

DUODENUM I CELLS key TASTE RECEPTORS: HORMONE released:

Answer 29

for LONG-CHAIN FATTY ACIDS (LCFAs), AMINO ACIDS (UMAMI), BITTER -> CCK release (control satiety and motility)

Question 30

JEJUNUM ENTEROCYTES key TASTE RECEPTORS: HORMONE released:

Answer 30

SGLT-1 RECEPTOR for SUGARS (SWEET) -> GLP-1 RELEASE (insulin, regulate blood glucose)

Question 31

ILEUM L CELL key TASTE RECEPTORS: HORMONE released:

Answer 31

SUGARS (SWEET), LCFAs, AMINO ACIDS, BITTER -> GLP-1 RELEASE

Question 32

COLON L-CELLS key TASTE RECEPTORS: HORMONE released:

Answer 32

SHORT CHAIN FATTY ACIDS -> PYY and GLP-1 RELEASE (satiety, ion secretion, motility)

Question 33

CCK secreted from which CELLS

Answer 33

I CELLS in DUODENUM

Question 34

CCK I CELLS have which TASTE RECEPTORS (what do they taste)

Answer 34

LCFAs, PROTEIN/AAs (UMAMI) & BITTER

Question 35

what does CCK STIMULATE

Answer 35

PANCREATIC SECRETIONS - protease, amylase, lipase, secretin GALLBLADDER CONTRACTION

Question 36

what does CCK INHIBIT

Answer 36

FOOD INTAKE & reduces GASTRIC EMPTYING (motility)

Question 37

SGLT-1 is the MAJOR ROUTE for ABSORPTION of SUGARS from INTESTINAL LUMEN into..

Answer 37

ENTEROCYTES -> BLOOD

Question 38

what is the MAJOR ROUTE for ABSORPTION of SUGARS from INTESTINAL LUMEN

Answer 38

SGLT-1

Question 39

GLUCOSE also STIMULATES the RELEASE of which GUT HORMONE

Answer 39

GLP-1 (L CELLS) -> stimulates INSULIN RELEASE from Pancreas (increase glucose uptake to tissues and enhancing enterocyte glucose uptake via increasing expression of SGLT-1 and GLUT2 in enteroycytes)

Question 40

which TRANSPORTERS are used to TRANPORT GLUCOSE across ENTEROCYTES

Answer 40

1. SGLT-1 glucose transported with Na+ 2. GLUT2 transports glucose out also NA+-K+ ATPase for conc. gradient

Question 41

GLP-1 STIMULATES the EXPRESSION of which TASTE RECEPTOR

Answer 41

SGLT-1 - SWEET TASTE (glucose)

Question 42

as GLUCOSE is TRANSPORTED through ENTEROCYTE in ABSORPTION, what FOLLOWS (is also absorbed)

Answer 42

Cl- through TIGHT JUNCTIONS -> H2O also FOLLOWS (H2O ABSORPTION)

Question 43

future clinical potentials of TASTE RECEPTOR targetting:

Answer 43

- compounds that Block activation of gut's taste receptors might serve as appetite suppressants - selective targeting of taste receptors to release hormones that signal feelings of FULLNESS (ie cck) - activating taste receptors of gut L-cells to release GLP-1 for Insulin release may treat Diabetes