Unit 4 Digestive Physiology (BIOL 460)

List the four basic digestive processes

motility, secretion, digestion, absorption

Motility is primarily accomplished by ___ muscle

smooth

Motility refers to ___ movements, moving food forward through the GI tract

propulsive

Motility refers to mixing movements, mixing digestive juices with food and facilitating ___

absorption

List the two types of secretion produced by the digestive system

exocrine and endocrine

Exocrine secretion involves the secretion of ___ ___

digestive juices

Digestive juices are secreted into the lumen of the GI tract with ___, ___, or ___

enzymes, bile salts, or mucus

The water volume in the GI tract is extracted from

plasma

Endocrine secretion involves the secretion of ___ ___

peptide hormones

Endocrine secretion is secretion into the ___

blood

Endocrine cells are organized as ___ cells scattered along the GI tract

individual

The purpose of digestion is to break down complex food macromolecules into smaller absorbable units that can be transported across the plasma membrane of cells lining the

small intestine

Carbohydrates are absorbed in the form of

monosaccharides

What is an example of an insoluble fiber? insoluble ___

cellulose

What is an example of a soluble fiber? soluble ___

pectin

Dietary protein is mostly absorbed as

amino acids

Dietary fats (triglycerides) are absorbed as

two fatty acids and a monoglyceride

What type of substances are absorbed in the stomach?

lipid soluble

List some examples of lipid soluble substances

alcohol and aspirin

What is absorbed by the small intestine

nutrients, electrolytes, and water

What is absorbed by the large intestine

salt and water

A branching network of nerves is called the

nerve plexus

The two pluxses in the Gi tract regulate local ___ activity

gut

The plexuses in the GI tract are assisted by GI ___

hormones

Smooth muscle is ___-shaped

spindle

Smooth muscle ___ (is/is not) striated

is not

Smooth muscle ___ (does/does not) contain actin and myosin filaments

does

Myofilaments are arranged ___ (up and down/diagonally) in a smooth muscle cell

diagonally

Myosin heads are present along ___ (part of/the entire length) of the thick filament in smooth muscle

the entire length

Myosin heads pull in the ___ (same/opposite) direction in smooth muscle

opposite

In smooth muscle the ___ ___ ___ controls cross-bridge formation

myosin light chain

Cytosolic calcium binds to ___ to activate the myosin light chain reaction sequence

calmodulin

In smooth muscle, most calcium comes from

extracellular fluid

___ smooth muscle contracts in bursts and is triggered by action potentials

phasic

___ smooth muscle is partially contracted at all times

tonic

Tonic smooth muscle increases and decreases based on ___ influx

calcium

What is a major location of tonic smooth muscle

arterioles

___ smooth muscle is controlled by autonomic neurons in multiple, discrete units that function independently

multiunit

List an example of where we see multiunit smooth muscles

goose bumps

___ smooth muscle acts as a functional syncytium

single unit

List an example of where we see single unit smooth muscles

uterus

The GI tract is technically ___ (inside/outside) the body

outside

List the order of food travel through the GI tract from the oral cavity to the rectum

oral cavity, pharynx, esophagus, stomach, small intestine, large intestine, rectum

The GI tract is like a

donut

Another name for the large intestine

colon

In the mouth oral cavity, ___ digestion begins

carbohydrate

The pharynx is for

swallowing

The esophagus pushes food down to the stomach via

peristalsis

The stomach is primarily for

storage

The stomach begins digestion of ___ and some ___

protein, lipid

The stomach is the physical breakdown of food by

acid

The small intestine is where the majority of ___ and ___ occurs

digestion and absorption

What macromolecules are digested by the small intestine

carbohydrates, lipids, proteins

The large intestine is for the dehydration and compaction of ___ materials

indigestible

The liver adjusts blood nutrient levels by secretion of

bile

The liver ___ fats and absorbing fat-soluble vitamins

emulsifies

The gallbladder is for the storage and concentration of

bile

Salivary glands produce and secrete

saliva

The pancreas secretes ___ and ___ ___

bicarbonate and digestive enzymes

The pancreas is most known for its secretion of ___ and ___

insulin and glucagon

Smooth muscle cells communicate by ___ ___

gap junctions

The autonomic smooth muscle function which coordinate peristalsis is maintained by ___ cells

cajal

Cajal cells generate the BER, which stands for the ___, otherwise called slow-wave potentials

basic electrical rhythm

List the two intrinsic nerve plexuses that regulate the short reflexes to change muscular activity

submucosal, myenteric

The two plexuses allow the gut to act ___ of the CNS

independently

The ___ plexus regulates peristalsis, sphincter control, and churning

myenteric

The process of mixing food with enzymes (and acids) within the stomach

churning

The ___ plexus regulates the secretion of water/electrolytes, absorption of nutrients, and local blood flow to the GI tract

submucosal

The intrinsic nerve plexuses make up the ___ nervous system

enteric

Extrinsic nerves are long reflexes that come from the

CNS

Sympathetic influence of the GI tract ___ (activates/inhibits) GI contraction and secretion

inhibits

Parasympathetic influence of the GI tract ___ (activates/inhibits) motility and secretion

activates

Gastrointestinal ___ act as the chemical messengers that translate signals from chemoreceptors, mechanoreceptors, and osmoreceptors into motility, digestion, secretion, etc.

hormones

There are ___-receptors in the wall of the GI tract which detect how much food is passing

mechano

There are ___-receptors in the lumen of the GI tract that detect changes in the chemical environment, such as nutrient levels, pH, and osmolarity

chemo

There are ___-receptors that detect changes in water and solute content

osmo

One way we regulate the salivary is by the ___ salivary reflex which is in response to food in the oral cavity

simple

Another way we regulate the salivary is by the ___ salivary reflex which is in response to the sight, smell, or thought of food

conditioned

When influenced by the parasympathetic NS, saliva is in ___-quantity, ___ and ___-rich

high, water, enzyme

When influenced by the sympathetic NS, saliva is in ___-quantity, ___ and ___-rich

low, thick, mucus

If you’re nervous, your mouth becomes dry because of the ___ NS

sympathetic

Regulation of gastric activity refers to the regulation of the

stomach

Regulation of gastric pits in the stomach occurs because of a multitude of cells. ___ cells are the goblets that release the thick material that provides a barrier between the food and epithelial cells

mucous

Regulation of gastric pits in the stomach occurs because of a multitude of cells. ___ cells proliferate for a 3-day turn over of our mucous lining

stem

Regulation of gastric pits in the stomach occurs because of a multitude of cells. ___ cells secrete HCl to lower pH

parietal

Regulation of gastric pits in the stomach occurs because of a multitude of cells. ___ cells secrete pepsinogen so that low pH can activate it and turn it into the digestive enzyme pepsin

chief

Regulation of gastric pits in the stomach occurs because of a multitude of cells. ___ cells secrete hormone and paracrine messagers

enterendocrine

List the three phases of gastric activity

cephalic, gastric, intestinal

The cephalic phase of gastric activity is stimulated by ___ of food

thoughts

The cephalic phase of gastric activity occurs ___ food enters

before

The cephalic phase of gastric activity is primarily mediated by the ___ NS which prepares for food anticipated to come

parasympathetic

The gastric phase is ___ (stimulatory/inhibitory) of gastric activity

stimulatory

The gastric phase of gastric activity occurs ___ food enters the stomach

when

The body knows we’re in the gastric phase of gastric activity because of mechano stretch receptors and partially digested ___

protein

The gastric phase of gastric activity secretes the hormone ___ from the stomach into the blood to stimulate motility and secretion of HCl

gastrin

The gastric phase of gastric activity secretes the paracrine signal ___ to stimulate HCl secretion

histamine

The intestinal phase is ___ (stimulatory/inhibitory) of gastric activity

inhibitory

The intestinal phase of gastric activity prevents us from eating ___ (too little/too much)

too much

One way the intestinal phase of gastric activity works is by gastric ___, the release of partially digested food, called chyme, into the duodenum

emptying

Gastric emptying is effective for the intestinal phase of gastric activity because it removes the ___ that activated gastric secretion for motility

stretch