NSG 530- Exam 3 Wilkes Questions and Verified Detailed Answers; for Guaranteed Success -Wilkes University

Role of digestive system

produce energy from food ingested, transfer energy-rich nutrients, water, and electrolytes into the body's internal environment

gastrointestinal tract components

mouth, esophagus, stomach, small intestine, large intestine, rectum, anus

functions of the gastrointestinal system

movement, secretion, digestion, and absorption

alimentary canal

GI tract-digestive tube that extends from the mouth to the anus

single hallow tube

Layers of the gastrointestinal tract

mucosa(outermost), submucosa, muscularis, serosa/adventitia (innermost)

enteric (intramural) plexus

controls mobility, secretion, sensation and blood flow

functions of saliva

lubrication, antibacterial action, pH regulation, thermoregulation, enzymatic digestion

phases of swallowing

oropharyngeal and esophageal

oropharyngeal swallowing

voluntary (striated) food formed into bolus and forced towards pharynx

esophageal swallowing

involuntary (smooth muscle) food bolus enters esophagus, peristalsis occurs to move food down to lower esophageal sphincter

how many permanent teeth are there in adults

32

three pairs of salivary glands

parotid glands, sublingual glands, submandibular glands

Saliva has a pH of

about 7.4, used to neutralize bacterial acids and prevents tooth decay

mucin

sticky mucus that lines digestive and respiratory tract traps microorganisms- provides lubrication

upper esophageal sphincter

Keeps air from entering the esophagus during respiration

lower esophageal sphincter

Prevents regurgitation from the stomach and caustic injury to the esophagus

Functions of the stomach

stores food

secretes digestive juices

mixes food with the juices

propels partially digested food (chyme) into duodenum

Chyme

Partially digested, semiliquid food mixed with digestive enzymes and acids in the stomach.

functional areas of the stomach

the fundus (upper portion), body (middle portion), and antrum (lower portion).

cardiac orifice

opening between esophagus and stomach

pyloric sphincter

ring of muscle that guards the opening between the stomach and the duodenum

pylorus

distal region of the stomach, opening to the duodenum

The stomach has three layers of muscle

- longitudinal, circular, and oblique (most prominent)

rugae

the folds in the mucosa lining the stomach

the stomach is impermeable to what?

water, but can absorb alcohol and aspirin as they are lipid soluble.

blood to stomach is supplied by _____?

celiac artery- abundant!

Three phases of gastric secretion

1. cephalic phase

2. gastric phase

3. intestinal phase

Motilin

increases peristalsis

Secretin

decreases peristalsis

Gastric mixing and emptying

- Retropulsion

- Rate dependent on volume, osmotic pressure, and chemical composition

Stimulation of gastric secretion

-Eating

-Gastrin

-Paracrine pathways

-Acetylcholine

-Chemicals

--Ethanol, coffee, protein

intrinsic factor

makes the absorption of vitamin B12 happen

gastroferritin

binds Fe2+ and transports it to small intestine

phases of gastric secretion

1. cephalic phase

2. gastric phase

3. intestinal phase

Gastric juices include

- Pepsin, an enzyme that digests protein

- Other Enzymes

- Hydrochloric Acid

- Mucus

- Salts

- Water

acid plays what role in gastric secretion?

dissolves food fibers, act as bactericide, convert pepsinogen to pepsin

Pepsin

Enzyme that breaks down proteins in the stomach

secreted by chief cells

Mucous in stomach

Protects stomach cells from gastric juices

small intestine

Digestive organ where most chemical digestion and absorption of food takes place

Three sections of the small intestine

1. Duodenum

2. Jejunum

3. Ileum

ileocecal valve

valve between the ileum of the small intestine and the cecum of the large intestine

peritoneum

Double-layered membrane surrounding the abdominal organs

mesentery

a fused double layer of the parietal peritoneum that attaches parts of the intestine to the interior abdominal wall

duodenum

first part of the small intestine- supplied by the gastroduodenal artery

jejunum

second part of the small intestine-supplied by mesentery artery

ileum

the last and longest portion of the small intestine-supplied by mesentery artery

myenteric plexus

controls gastrointestinal motility

Two layers of small intestine

longitudinal (outer) and circular (inner)

absorption through villi:

enterocytes

microvilli

brush border

lamina propria

lacteal

crypts of Lieberkühn

Intestinal Digestion and Absorption

-hydrochloric acid

-pepsin

-pancreatic enzymes

-intestinal enzymes

-bile salts

Crypts of Lieberkuhn

Glands located at the base of the intestinal villus

reflexes that inhibit intestinal motility

ileogastric reflex, intestinointestinal reflux, gastroileal reflex

Peristalsis

Involuntary waves of muscle contraction that keep food moving along in one direction through the digestive system.

large intestine

The last section of the digestive system, where water is absorbed from food and the remaining material is eliminated from the body

Parts of the large intestine in order

cecum, ascending colon, transverse colon, descending colon, sigmoid colon, rectum, anal canal

teniae coli of the large intestine

three bands of longitudinal smooth muscle in muscularis

haustral contractions

circular muscles of the colon

most contractions of colon, where haustra sequentially contract in response to distension

Slow segmenting movements, mostly in ascending and transverse colon

superior mesenteric artery

large abdominal artery; feed large and small intestine

Valsalva maneuver

forcible exhalation against a closed glottis, resulting in increased intrathoracic pressure

Role of bacterial flora

-ferment undigestible carbohydrates (cellulose)

-synthesize vitamins B and K

-release a mixture of gases (flatus)

-decompose bilirubin to give feces brown color

-is a desirable component

epinephrine and exogenous opioids

inhibit contractile activity

GALT

gut associated lymphoid tissue

GALTs role

major role in immune defenses by killing many microorganisms

mucosal secretions in the GI system

produce IgA antibodies

intestinal microbiome

Numbers of bacteria increase from proximal to distal GI tract

-Highest in colon

Multiple factors affect normal composition of bacterial flora

-Genetics, diet, environmental, drugs

Alert immune system to protect against infection

Splanchnic blood flow

-Provides blood flow to esophagus, stomach, small and large intestine, liver, gallbladder, pancreas, spleen

Accesory organs of the digestive system

liver, gallbladder, pancreas

The liver is divided into

right and left lobes

right liver lobe is then divided into ____ and _____

caudate and quadrate lobes

faliciform ligament

attaches liver to anterior abdominal wall and diaphragm

Glisson's capsule

Fibrous capsule that encloses the liver

blood supply to liver

hepatic artery and hepatic portal vein

hepatocytes

functional cells of the liver, can regenerate

immune functions of the liver

Kupffer cells-phagocytic, important for healing after liver injury

stellate cells- trap bacteria, remove foreign substances from blood

natural killer cells-important in tumor defense

disse space-drains interstitial fluid into hepatic lymph system

Kupffer cells

macrophages in the liver. found in liver sinusoids and re important for liver healing and liver injury. bactericidal.

Bile

a digestive juice secreted by the liver and stored in the gallbladder. alkaline, bitter tasting-yellowish/green fluid. 700-1200mL secreted per day

enterohepatic circulation

A continual recycling of compounds such as bile acids between the small intestine and the liver.

Bile acid pool

Refers to the fact that most bile salts are recycled

They go through the pool 4-12x a day

Only 5% are lost in faeces, the remainder are reabsorbed in the terminal ileum

Primary bile salts

cholic acid and chenodeoxycholic acid

Secondary bile salts

deoxycholic acid and lithocholic acid

Bilirubin

orange-yellow pigment in bile; formed by the breakdown of hemoglobin when red blood cells are destroyed

Unconjugated bilirubin

breakdown product of heme, lipid soluble, never in urine

conjugated bilirubin

water soluble, excreted in bile

Urobilinogen

reabsorbed in intestines and excreted in urine as urobilin

Liver functions

Responsible for: The metabolism of fats, proteins, and carbohydrates. Excretion of bilirubin, cholesterol, hormones, and drugs. Enzyme activation. Storage of glycogen, vitamins, and minerals. Synthesis of plasma proteins, such as albumin, and clotting factors. Blood detoxification and purification. Bile production and secretion.

Gallbladder function

Store & concentrate bile produced by the liver until it is needed in the small intestine

Pancreas

An organs in the abdominal cavity with two roles. The first is an exocrine role: to produce digestive enzymes and bicarbonate, which are delivered to the small intestine via the pancreatic duct. The second is an endocrine role: to secrete insulin and glucagon into the bloodstream to help regulate blood glucose levels.

exocrine pancreas

part of the pancreas that secretes digestive enzymes and bicarbonate into the duodenal lumen

Pancreatic innervation

celiac and superior mesenteric plexuses. arises from parasympathetic neurons of the vagus nerve.

pancreas enzymes

enzymes are secreted in inactive forms to protect the pancreas from the digest effects of its own enzyme. Pancreatic juices (Bicarbonate, lipase, trypsin(ogen), proteases, and amylase)

trypsin inhibitor

prevents the activation of proteolytic enzymes while they are in the pancreas

Enterokinase

A duodenal enzyme that activates trypsinogen (from the pancreas) to trypsin.

hydrochloric acid

substance produced by the stomach; necessary for digestion of food. dissolves food particles, acts as a bactericide against swallowed organisms and converts pepsinogen to pepsin.

Chymotrypsin

trypsin found in chyme

Segmentation

consists of localized rhythmic contractions of the circular smooth muscles.

vagal stimulation

regulates intestinal motility

clinical manifestations of gastrointestinal dysfunction

anorexia

vomiting

constipation

diarrhea

abdominal pain

gastrointestinal bleeding

anorexia

A lack of a desire to eat despite physiologic stimuli that would normally produce hunger

Vomiting (emesis)

The forceful expulsion of the contents of ones stomach through the mouth

constipation

Infrequent and difficult bowel evacuation

primary condition- functional

secondary condition- caused by many factors including diet, medications, aging