Gastrointestinal Physiology Exam 1 (IP3): Introduction to Gastrointestinal Physiology Lecture

Carbohydrates, lipids, and fats are (micronutrients/macronutrients)

macronutrients

Vitamins and minerals are (micronutrients/macronutrients)

micronutrients

Animals require _____ and _________

energy, nutrients

(energy/nutrients): building blocks for body structures and biochemical functions

nutrients

(energy/nutrients) powers biological functions like movement, growth, and maintenance

energy

assimilation of nutrients involves what two processes?

digestion, absoprtion

__________ is defined as the process of breaking down food by mechanical and enzymatic action into substances that can be used by the body

digestion

digestion is defined as the process of breaking down food by __________ and ______________ action into substances that can be used by the body

mechanical, enzymatic

(enzymatic/mechanical) digestion is physically breaking down food substances into smaller particles to increase surface area

mechanical

mastication, peristalsis, and segmentation are all forms of (mechanical/enzymatic) digestion

mechanical

peristalsis and segmentation fall under the category of (mastication/kneading and churning) category of mechanical digestion

kneading and churning

define borborygmus

stomach growling

(mechanical/enzymatic) digestion is the process of breaking down large, complex food molecules into smaller, simpler molecules for absorption

enzymatic

enzymatic digestion is the process of breaking down large, complex food molecules into smaller, simpler molecules for _______________

absorption

list four basic gastrointestinal exocrine secretions that aid in digestion

water

electrolytes

enzymes

mucus

digestion occurs (inside/outside) the body

outside

GI epithelium has a (fast/slow) turnover rate

fast

- bacterial invasion

- extremes in pH (acid, alkaline)

- toxins

- enzymatic action (proenzymes or zymogens)

what do all of these listed above have to do with the GI tract?

external-internal environmental interface

what are the three components of the gastrointestinal barrier?

mucus, epithelium, enzymes

why does digestion occur "outside" of the body

to protect the body from the digestive process

what happens to shed intestinal cells?

they are digested

the GI barrier prevents _____________, which protects the GI tract

autodigestion

define autodigestion

when digestive enzymes destroy the body's tissues

when water molecules break a compound into two smaller parts is known as _____________

hydrolysis

proteins are digested via what process?

hydrolysis

what are the three absorbable form of proteins?

- amino acids

- di-peptides

- tri-peptides

proteins enter the body via the ______

blood

what is the ingested form of proteins

proteins

what is the ingested form of carbohydrates

complex polysaccharides

proteins are digested via what process

hydrolysis

(starches/cellulose) are soluble carbohydrates

starches

(starches/cellulose) are insoluble carbohydrates

cellulose

(cellulose/starches) are digested via hydrolysis of a-1,4-glycosidic bonds via mammalian enzymes

starches

(cellulose/starches) are digested via hydrolysis of B-1,4-glycosidic bonds via microbial enzymes

cellulose

Cellulose is digested via hydrolysis of B-1,4-glycosidic bonds via (mammalian/microbial) enzymes

microbial

starches are digested via hydrolysis of a-1,4-glycosidic bonds via (mammalian/microbial) enzymes

mammalian

starches are digested via hydrolysis of (B-1,4/a-1,4) glycosidic bonds

a-1,4

cellulose is digested via hydrolysis of (B-1,4/a-1,4) glycosidic bonds

B-1.4

what is the absorbable form of starches?

monosaccharides

what is the absorbable form of cellulose?

volatile fatty acids (VFAs)

carbohydrates enter the body via the ________

blood

what is the ingested form of fat

triglycerides

______ _________ break up large fat globules into smaller droplets; form complexes called micelles

bile salts

bile salts form complexes called ____________

micelles

digestion of fat happens via what process

hydrolysis

what are the three absorbable forms of fat

- free fatty acids

- monoglycerides

- glycerol

the absorbable forms of fat are exported in ____________

chylomicrons

where in the body are absorbable fats re-esterified into triglycerides?

intestinal epithelial cells

fats enter into the body via the _____

lymph

(carnivores/herbivores) have the longest and most complex GI tract as well as the longest transit time

herbivores

(carnivores/herbivores) have the simplest and shortest digestive tracts as well as the shortest transit time

carnivores

why do herbivores have the longest most complex digestive systems?

enables consumption of difficult to digest plant material

____________ is when symbiotic microbial organisms break down fibrous plant materials into VFAs, B vitamins, and amino acids (microbial protein)

fermentation

(foregut/hindgut) fermenters have enlarged fermentation compartments in the cecum and/or colon

hindgut

(foregut/hindgut) fermenters have a pre-gastric fermentation chamber (rumen)

foregut

ruminants are (foregut/hindgut) fermenters

foregut

horses are (foregut/hindgut) fermenters

hindgut

rabbits are (foregut/hindgut) fermenters

hindgut

the epithelium of the alimentary tract begins as __________________ and ends as ____________________

- stratified squamous epithelium

- stratified squamous epithelium

what structure is at the end of the alimentary tract

anus

T/F: the alimentary tract is not resistant to abrasion

false

it is resistant to abrasion

the alimentary tract is primarily lined by what kind of epithelium

simple columnar epithelium

Choose the correct description for the large intestine

A. Food storage and digestion

B. Digestion and nutrient absorption

C. Water absorption, waste elimination, and fermentation of plant materials (herbivores)

C

Choose the correct description for the stomach

A. Food storage and digestion

B. Digestion and nutrient absorption

C. Water absorption, waste elimination, and fermentation of plant materials (herbivores)

A

Choose the correct description for the small intestine

A. Food storage and digestion

B. Digestion and nutrient absorption

C. Water absorption, waste elimination, and fermentation of plant materials (herbivores)

B

T/F: Waste elimination occurs in the small intestine

false

Large intestine

Crypts are (absorptive/secretory) domains

secretory

villi are (absorptive/secretory) domains

absorptive

surface epithelium are (absorptive/secretory) domains

absorptive

villi are found in the (small/large) intestine

small

surface epithelium is found in the (small/large) intestine

large

Choose which kind of cell type enterocytes and colonocytes are classified as

- stem cells

- paneth cells

- goblet cells

- enteroendocrine cells

- tuft cells

- absorptive cells

absorptive cells

enterocytes are absorptive cells found in the (large/small) intestine

small

colonocytes are absorptive cells found in the (large/small) intestine

large

Greater than 80% of cells found in the GI tract are these:

- stem cells

- paneth cells

- goblet cells

- enteroendocrine cells

- tuft cells

- absorptive cells

absorptive cells

nutrients from digested food are transported from the GI tract into the _______ or ________

blood, lymph

Does active transport require cell energy?

yes

is active transport exclusively transcellular?

yes

T/F: absorption of most nutrients and electrolytes is via active transport

true

in terms of passive transport, lipids and VFAs are absorbed (transcellularly/paracellularly)

transcellularly

in terms of passive transport, electrolytes are absorbed (transcellularly/paracellularly)

paracellularly

action of the Na-K ATPase is via (primary/secondary) active transport

primary

Na+ wants to be (outside/inside) of the cell

inside

what is the cell membrane potential?

-45 mV

what is the driving force of Na+ into the cell?

-105 mV

Which epithelial transport proteins are found on the luminal membrane?

A. Na-K ATPase

B. Nutrient specific transporters

C. Na+/H+ exchanger

D. Cl- and HCO3- cotransporters

E. Nutrient specific facilitated diffusion transporters

F. Cl-/HCO3- exchanger

B, C, F

Which epithelial transport proteins are found on the basolateral membrane?

A. Na-K ATPase

B. Nutrient specific transporters

C. Na+/H+ exchanger

D. Cl- and HCO3- cotransporters

E. Nutrient specific facilitated diffusion transporters

F. Cl-/HCO3- exchanger

A, D, E

nutrient absorption occurs primarily in the (small/large) intestine at the _________

small, villi

nutrient absorption is controlled by what?

nutrient availability

T/F: nutrient absorption has a lot of neuroendocrine control

false

little control

the electrochemical force of Na+ to enter the cell is established by what structure?

Na-K ATPase

T/F: NaCl coupled absorption is closely regulated by the neuroendocrine system

true

NaCl absorption occurs in the epithelium of which two structures of the GI system?

large and small intestine

NaCl absorption occurs in the (villi/surface epithelium) of the small intestine

villi

NaCl absorption occurs in the (villi/surface epithelium) of the large intestine

surface epithelium

NaCl coupled absorption is an important transport process for maintaining body ______ balance

fluid

NaCl coupled absorption is inhibited (before/during/after) a meal

during

- It is inhibited during the meal because luminal NaCl and water is needed for digestion and absorption

During a meal, NaCl coupled absorption is inhibited. When is the process reactivated?

after digestion

NaCl and water secretion occurs via what epithelium structures?

crypts

carriers bring Cl- and HCO3- into the cell via the electrochemical gradient of what molecule?

sodium