Digestive System - Final

Six function of digestive system - I Sing Musical Duets at Dawn

Ingestion, Secretion, Mixing & propulsion, Digestion - chemical and mechanical , Absorption, Defecation

What are the two divisions of the Dig system

1. Alimentary Canal (GI tract): main functions are digestive and absorption, continuous tube that food passes through

2. Accessory Organs (AO): Assist in the digestive process and many of them have functions that are associated with other body systems

Four layers of GI tract (in-out)

1. Mucosa:Most inner

2. Submucosa: CT that contains blood nerve and lymph vessels

3. Muscularis Externa: Smooth muscle layers

4. Serosa: connected to parietal peritoneum that lines abdominopelvic cavity and mesentery

Heartburn

Cardioesophageal vlave doesn’t close tightly and gastric juices from the stomach get into the esophagus

Three parts of the stomach

1. Fundus

2. Body

3. Pylorus

Peritoneum

The serous membrane lining the cavity of the abdomen and covering the abdominal organs

The GI tract (alimentary canal)

Oral cavity

Pharynx

Esophagus

Stomach

Small intestine

Large intestine (Rectum)

Anus

Accessory organs

Teeth & tongue

Salivary glands

Gallbladder

Liver

Pancreas

Baby teeth are also known as

deciduous

Adult teeth can be

impacted

What are the two main regions of teeth

Crown(exposed) and Root(in socket)

Cementum

one layer of tooth root

Attaches tooth to periodontal ligament

Periodontal ligament

Anchors tooth in bony socket of the jaw

Continuous with gingiva (gums)

Liver functions (Please Pick Some Processed Shrimp Down Main)

Produces bile (bile increases the absorption of fats)

Picks up glucose from blood

Stores glucose as glycogen

Processes fats and amino acids

Stores some vitamins

Detoxifies poisons and drugs

Makes the blood proteins

Hormone

chemical released by a cell, a gland, or an organ in one part of the body that affects cells in other parts of the organism

enzyme

catalyst that greatly accelerates both the rate and specificity of metabolic reactions

gastrin

• made in pylorus of stomach

• stimulates the secretion of gastric juice

Secretin

• produced by the mucosa of the G.I. tract when chyme from the stomach enters the S.I.

• stimulates secretion of pancreatic juice and bile

Cholecystokinin (CCK))

• Secreted in S.I.

• stimulates secretion of pancreatic juice and stimulates release of bile from gallbladder

• Induces a feeling of satiety (feeling full)

Secretin and CCK

work together to inhibit secretion of gastric juice and gastric emptying

Bile

• by the liver, enters duodenum through the common hepatic duct

• emulsifies fat molecules

• Gallbladder Stores bile when food is not being digested

Pancreatic amylase

breaks down complex carbohydrates (starch and glycogen) into simple sugars

Pancreatic lipase

further breaks down fats that have been emulsified by bile into fatty acids and glycerol

RIBONUCLEASE & DEOXYRIBONUCLEASE

Break down nucleotides into their 3 components (sugars, phosphate groups, nitrogenous bases)

TRYPSIN, CHYMOTRYPSIN, ELASTASE, CARBOXYPEPTIDASE

break down proteins into smaller peptides and individual amino acids

Digestive System Homeotasis

• Stimulus: Chyme enters the duodenum

• Receptors: mucosa cells in duodenum

• Input: release of secretin and CCK

• Control Center: cells of liver and pancreas

• Output: increased release of secretin and CCK

• Effector: cells of liver, gallbladder, and pancreas

• Outcome: release of bile and pancreatic juice

• Return to Homeostasis: chemical digestion and release of nutrients, inhibition of gastric emptying

Process of swallowing

The tongue pushes bolus against the soft palate. The uvula rises and closes off nasal passages. The bolus then enters the pharynx and the epiglottis covers the layrnx and get down to the stomach with the help of peristalsis.

Gall bladder

Stores and a concentration site for bile

Islets of Langerhans (AKA “islet cells”)

the hormone secreting cells

Insulin

• from beta cells

• Lowers blood glucose (sugar)

Glucagon

• from alpha cells

• Raises blood glucose (sugar)

Blood Sugar Homeostasis ( low)

• Stimulus: Low blood sugar

• Receptors: cells on pancreas detect decrease in blood glucose levels

• Input: Cells “send message” to control center

• Control center: alpha cells within pancreas

• Output by alpha cells: Alpha cells release glucagon which stimulates effectors

• Effectors: Liver receives glucagon and is stimulated to break down glycogen (stored) into glucose in the bloodstream.

Blood Sugar Homeostasis (high)

• Stimulus: High blood sugar

• Receptor: Cells in pancreas detect increase in blood glucose levels

• Input: Cells “send message” to control center

• Control center: Beta cells in pancreas

• Output: Beta cells release insulin which stimulates effectors

• Effector: Insulin stimulates liver to remove glucose from the blood and store it as glycogen

What valve is between the stomach and the small intestine

They pyloric valve

Major functions of small intestines

Absorption and digestion

What does mesentery do

binds the small intestines to the posterior abdominal wall

What are the section of the small intestine

1. Duodenum

2. Jejunum

3. ileum

Microvili

cylindrical, membrane covered projections

Circular folds

Increase the surface area of absorption

The small intestines absorb

90%

What valve is between the he small and large intestine

ileocecal valve

Gastric emptying

• Stimulus: chyme enters the duodenum

• Receptors: Mucosa cells in duodenum

• Input: release of secretin and CCK

• Control center: cells of liver and pancreas

• Output: Increase release of secret and CCK

• Effectors: Cells Liver, gallbladder and pancreas

• release of bile and pancreatic juice

• Chemical digestion, absorption of nutrients, inhibition of gastric emptying

The enzyme pancreatic lipase digests triglycerides into

fatty acids and glycerol