v2 Digestion AP2 - Packet 2, Movement, Layers, Mesenteries, Mouth

physical breakdown or mixing

mech digestion; examples are mastication, stomach mixing waves, segmentation

enzymatic breakdown of food molecules by hydrolysis

chem digestion; examples are enzymes using water to split chemical bonds

moving substances from the GI tract into blood or lymph

absorption

gentle stomach churning mixes food with gastric secretions

mixing waves

where do mixing waves occur?

stomach (forms chyme)

alternating contractions mix intestinal contents

segmentation

where does segmentation occur?

small intestine (improves digestion and absorption)

rhythmic contraction waves move contents along the GI tract

peristalsis (note it’s entire GI tract!)

where does peristalsis take place?

throughout the GI tract

distinct propulsion pattern in the large intestine

mass movement

innermost layer of the Alimentary Canal; includes epithelium and underlying tissue

mucosa

Mucosa has 3 jobs, what are they?

Hint: it gives, takes, and does something else

gives mucus and enzymes, takes nutrients, immune protection

What does mucosa contain that’s unique?

Glands and crypts, sensory receptors

thick connective tissue beneath mucosa

submucosa

Which layer of the alimentary canal contains blood vessels, lymphatics, nerves, and small glands?

Submucosa

What does the submucosal plexus do?

Help regulate gland secretions

This layer of the alimentary canal is usually inner circular and outer longitudinal smooth muscle.

Muscular externa

Which alimentary layer is responsible for mixing and propulsion?

Muscular externa

Which layer is associated with the myentaric plexus and what does it do?

Muscularis; controls motility

This outer layer blends with with nearby tissues

Adventitia

This outer layer includes visceral peritoneum

Serosa

Continuous, double layered serous membrane in the abdomen

Peritoneum

Supports organs and connects jejunum/ileum to posterior abdominal wall; carries BV, lymphatics, and nerves

Mesentery

Supports portions of the colon

Mesocolon

these teeth have flat cutting edges; nip or cut food

incisors

these teeth are pointed; pierce and tear food

canines

these teeth have broad surfaces for grinding food

premolars and molars

how many primary teeth?

20 deciduous / milk teeth

how many permanent teeth?

usually 32 adult teeth

Hard, non-living outer covering of the crown; protective

enamel

Living, calcified tissue that forms most of the tooth

Dentin (live in dentin)

Bone-like covering of the root; attachment for periodontal ligaments

Cementum

Contains blood vessels, nerves, and connective tissue of tooth

Pulp cavity / root canal

This begins starch digestion in the mouth

Salivary amylase

These begins lipid digestion

Lingual lipase

These neutralize bacterial acids and help protect enamel in saliva

Bicarbonate ions

These two help protect against bacterial infection in the saliva

Lysozyme and igA

lubricates and protects the GI lining

mucus

Largest pair of glands, in front of the ears; duct opens near second upper molar

Parotid glands

These glands are under the jaw, ducts open near either side of the lingual frenulum

Submandibular glands

These glands are below the tongue in the floor of mouth

Sublingual glands

This opens during swallowing

the upper esophageal sphincter

This helps prevent stomach contents from refluxing into the esophagus

lower esophageal sphincter

3 layers of the muscular externa

Outer longitudinal

Middle circular

Inner oblique

(extra oblique helps churn)

Region where the esophagus enters the stomach

cardia

Dome-shaped superior region of the stomach

Fundus

Distal funnel region of stomach

Pylorus

Controls passage of chyme from stomach into duodenum

Pyloric sphincter

These gastric gland cells secrete alkaline mucus

Surface mucous cells

These gastric gland cells protect stomach lining from acid and self-digestion

Surface mucous cells (remember the mucous protects the GI tract)

These cells secrete HCl and intrinsic factor

Parietal cells

HCl denaturs salivary amylase, helps kill bacteria, and activates

pepsinogen

These cells secrete pepsinogen and gastric lipase

chief cells

These cells secrete regulatory hormones like gastrin, which helps regulate digestive activity

Endocrine

First, proximal segment of the Small Intestine; major region of chemical digestion; receives bile and pancreatic secretions.

Duodenum

Segment of small intestine that contains Peyer’s patches and is in the middle

Jejunum

Segment of the small intestine that deals with major nutrient absorption and bile salt reabsorption; also contains Peyer’s patches

Ileum

Large folds that increase absorptive surface area and mix/slow contents in the small intestine

Circular folds

Projections of the mucosa that increase surface area in the small intestine

Villi

Tiny projections on absorptive cells of Small Intestine; form the brush border and increase surface area

Microvilli

Bile salts do this to lipids to increase surface area for enzyme action

Emulsify; making them into smaller droplets of lipids

the liver receives nutrient rich blood from the digestive tract through the ________ _____ ____ before that blood enters general circulation

hepatic portal vein

Hexagonal region of liver tissue

Lobule

At each corner of the liver: hepatic portal vein, hepatic artery, and hepatic duct

Portal triad (vad)

At the center of the liver lobule; drains toward hepatic veins and then the inferior vena cava

central vein

food enters the stomach and ______ cells are stimulated to release _______

endocrine cells release gastrin

this triggers closing of the lower esophageal sphincter

Hcl