Unit 3: Digestive System

Organs of the GI system fall into which 2 groups?

Alimentary Canal and Accessory Organs

The Alimentary Canal is aka the _____ or ______.

GI tract or Gut

The __________ is continuous muscular tube running from mouth to anus.

alimentary canal

What are 5 parts of the Alimentary Canal?

mouth, pharynx, esophagus, stomach, intestines, and anus

What are the 4 accessory organs?

teeth, tongue, gall bladder, digestive glands (salivary glands, liver, and pancreas)

What are the 6 steps of the GI system?

1) ingestion

2) Propulsion

3) Mechanical Breakdown

4) Digestion

5) Absorption

6) Defecation

_______ is the contraction-relaxation waves that move food distally along the GI tract.

peristalsis

What are the two organs where propulsion (peristalsis) occur?

esophagus and colon

Chewing is aka ______.

mastication

_______ is the alternating contraction-relaxation waves move food backward and forward, mixing with digestive juices.

segmentation

Where does segmentation occur?

small intestine

_______ is a series of catabolic steps where enzymes break down complex food molecules into chemical building blocks (nutrients).

digestion

________ is the passage of digested nutrients from GI tract into blood or lymph.

absorption

_________ is the serous membranes of the abdominal cavity.

Peritoneum

What are the 3 parts of the peritoneum?

visceral, parietal, and mesentery

The ______ peritoneum is the membrane on external surface of most digestive organs.

visceral

The ______ peritoneum is the membrane lining the abdominal cavity.

parietal

The _______ is the double-layer of the peritoneum extending from the body wall to digestive organs.

mesentery

What is the function of the mesentery layer of peritoneum?

anchors organs, stores fat, and provides a route for blood vessels, lymph, and nerves

The __________ is the fluid-filled space between peritoneal layers lubricating digestive movements.

peritoneal cavity

Organs located within peritoneum are ________. Organs located outside/posterior to peritoneum are _________.

intraperitoneal; retroperitoneal

________ is inflammation of the peritoneum caused by wound, ulcer, and ruptured appendix.

peritonitis

The mouth is also known as the _________.

Buccal Cavity

The tongue forms a _____ of food-saliva mixture.

bolus

Salivary glands produce _____ mL of saliva per day.

1500

Salivary glands _____, ______, ______, and _______.

cleanse mouth, dissolve food, moisten food, and begin carb breakdown

Which type of tooth?

1) ______ chisel-shaped for cutting.

2) ______ fang-like for tearing or piercing.

3) ______ are rounded cusps for grinding and crushing.

4) _____ are rounded cusps, best grinders.

1) incisors

2) canines

3) premolars (bicuspids)

4) molars

________ is a congenital condition where the lingual frenulum anchoring the tongue is extremely short.

ankyloglossia

Ankyloglossia is aka ________.

tongue-tied

______ is inadequate saliva production and it is a cause of bad breath.

xerostomia

Xerostomia is aka ______.

dry mouth

Swallowing is known as ______.

deglutition

Upon swallowing, the tongue propels food posteriorly into the ________ and then to the ________. Food then travels down the ________.

oropharynx, laryngopharynx, esophagus

The esophagus is a flat, muscular tube that runs from the ________ to the _______.

laryngopharynx to the stomach

The esophagus joins the stomach at the ____________.

gastroesophageal (cardiac) sphincter

Mucus on either side of the cardiac sphincter protects against ________.

acid reflux

The ______ is the temporary storage tank for food.

stomach

When the stomach is empty, it is ____ mL volume, but can expand up to ___ L capacity.

50; 4 (80x)

The folds in the stomach are called ______.

rugae

The stomach converts food bolus into paste-like _______.

chyme

Chyme = _____ + ______.

mixture of foos + gastric juices

Chyme exits the stomach via the ________ into the _______ of the small intestine.

pyloric sphincter; duodenum

What are the 4 glandular cells of the stomach?

mucus cells, parietal cells, chief cells, and enteroendocrine cells

_______ cells secrete bicarbonate protecting stomach lining from acids.

mucus

A _________ is where acid has eaten through the stomach lining.

peptic/gastric ulcer

Parietal cells secrete ________ and _______.

hydrochloric acid (HCl) and intrinsic factors

What is the function of HCl?

denatures proteins, activates pepsin, and kills bacteria

Chief cells secrete ______ and _______.

pepsinogen and lipase enzymes

Pepsinogen aids in _______ and is activated by ______.

protein digestion; pepsin

What does lipase do?

digests lipids

_________ cells secrete chemical messengers.

enteroendocrine

What are the 6 enteroendocrine cells?

serotonin, gastrin, histamine, somatostatin, ghrelin, and petin

Serotonin promotes _______ and _______.

persistalsis and segmentation

Gastrin promotes _______ and ______.

GI motility and acid release

Histamine regulates _________.

acid secretion

Somatostatin antagonizes _________.

serotonin

Ghrelin sends _____ signals to the brain.

hunger

Leptin sends ______ signals to the brain.

full

Gastric mucosa secretes _____ L of juices per day.

>3

Vagus nerve stimulation ______ secretions. Sympathetic stimulation ________ secretions. Gastrin secretions from enteroendocrine cells _______ HCl production.

increases; decreases; and increases

How long does it take to break down each nutrient?

Carbs

Proteins

Fats

2; 4; 6 hrs

What part of the small intestine can prevent overfilling by regulating how much chyme is allowed to enter?

duodenum

Vomiting is aka ______.

emesis

The small intestine is a major organ of _______ and _______.

digestion and absorption

The small intestine runs ______ ft long from the _________ of stomach to the __________ of large intestine. Also has a _____ diameter.

15-20; pyloric sphincter; ileocecal valve; 1-1.6 in

What is the purpose of fingerlike villi in the ileum and jejunum?

maximize internal surface area

Microvilli make up the _________. What is the purpose?

"brush border;" secretes digestive enzymes

What are the 3 digestive enzymes?

lactase, maltase, and sucrase

Where does final digestion and absorption of nutrients into the bloodstream occur?

ileum and jejunum

Digestion and absorption takes ______.

3-6 hrs

Bile is a yellow-green, _______ solution.

alkaline

What is the purpose of salts in bile?

emulsify fat in chyme and promote absorption

What is the purpose of bilirubin in bile?

gives feces its brown color when bacteria breaks it down in colon

The ______ secretes bile. The _______ stores and concentrates bile.

liver; gall bladder

Excess cholesterol in diet or too few bile salts can create ________.

gall stones

_______ is inflammation of the liver.

hepatitis

_______ is a progressive, chronic inflammation causing fatty, fibrotic tissue formation.

cirrhosis

The liver can regenerate from 80% removal in _______.

6-12 months

The pancreas is an exo-endocrine organ which secretes ________ (_______) as well as ______ and _______ (______).

pancreatic juices (exocrine); insulin & glucagon (endocrine)

Pancreatic juices mix with chyme in the _______ of small intestine.

duodenum

What are 5 pancreatic juices secreted from the pancreas?

bicarbonate (secretin), proteases, amylases, lipases, and nucleases

What is the purpose of bicarbonate?

neutralizes acidity sparing intestinal lining

What is the purpose of proteases?

denatures proteins

What is the purpose of amylases?

break down carbs

What is the purpose of lipases?

break down triglycerides (fats)

What is the purpose of nucleases?

break down nucleic acids

______ and _______ maintain blood glucose balance.

insulin and glucagon

_____ = glucose uptake from blood into tissues.

insulin

Glucagon stimulates liver ________.

glycogenolysis

_________ can be caused by anything that interferes with the delivery of bile or pancreatic juice.

malabsorption

What is a common malabsorption disease and what happens with it?

gluten-sensitive enteropathy (celiac); immune cells damage the intestinal villi and brush border

People with gluten-sensitive enteropathy have intestinal walls that appear _______ when viewed through an endoscope. They have villi ______ and appear ______.

scalloped; atrophy; flattened

The large intestine begins at the ______ and ends at the ______.

cecum; anus/rectum

The cecum attaches to the small intestine at the _________ and is superior to the ________.

ileocecal valve; appendix

The appendix is the _______ and ______ storehouse to recolonize gut microbiome.

lymphoid tissue and bacterial

Residue in the LI remains in colon for ______.

12-24 hours

Is the colon essential for life?

no

_________ are attached to the ileocecal valve in the event the colon must be bypassed/removed.

ileostomy bags

_______ function similarly to ileostomy bags but are attached at various, distal parts of the colon.

colostomies

Low-fiber diets can narrow the colon's diameters causing strong _______ and increased _______.

contractions; pressure