Physiology Digestive Physiology

Front 1

What is Digestion?

Back 1

The transfer of food from the external to the internal environments

Front 2

What are the stages of digestion?

Back 2

Ingestion
Propulsion
Mechanical and Chemical Digestion
Absorption
Defecation

Front 3

What does the alimentary canal consist of?

Back 3

The tube going from the mouth to the anus

Front 4

What are the accessory organs of the digestive system?

Back 4

Salivary Glands, Liver, Gall Bladder and Pancreas

Front 5

What is Mucus?

Back 5

A glycoprotein (mucin) plus water

Front 6

What is mucus secreted by?

Back 6

The lining of the entire Elementary Canal for lubrication and protection

Front 7

What is saliva made up of?

Back 7

Water, Salts, Mucin, Salivary Amylase, IgA, lysozymes and defensin

Front 8

What is saliva secreted by?

Back 8

The parotid (25%), sublingual and submandibular (majority) glands.

Front 9

What is the function of saliva?

Back 9

It moistens mouth and food, softens and lubricates food, cleanses mouth, and chemically digests

Front 10

How is saliva produced?

Back 10

The thought, taste, smell, sight or presence of food causes a reaction in which the salivary nuclei in the medulla are stimulated which in turn stimulates salivary glands to produce saliva

Front 11

What does mastication promote?

Back 11

Mechanical Digestion and mixing food with saliva

Front 12

What does Chemical Digestion promote?

Back 12

Salivary amylase converts carbs into dextrins

Front 13

What types of molecules can be absorbed by the oral mucosa?

Back 13

Only Water molecules

Front 14

What is deglutition?

Back 14

Swallowing

Front 15

Describe the voluntary phase of deglutition

Back 15

Food moves from the mouth to the pharynx by action of tongue

Front 16

What is the pharyngeal phase of deglutition controlled by?

Back 16

The Medulla

Front 17

How does the pharyngeal phase of deglutition mechanism work?

Back 17

Respiration is Inhibited
Larynx Raises and Glottis Closes
The Epiglottis closes off Trachea
Pharyngeal muscles contract forcing bolus into the esophagus

Front 18

What is the esophageal phase of deglutition controlled by?

Back 18

The Medulla

Front 19

Describe the mechanism for the esophageal phase of deglutition

Back 19

Circular Muscle layer above the bolus contracts, forcing it down
Longitudinal Smooth muscle layer below the bolus contracts, widening the esophagus to accept the bolus
The contractions occur in waves (peristalsis)
GE sphincter opens and bolus enter the stomach
GE sphincter closes

Front 20

What are they two types of cells in gastric glands?

Back 20

Parietal Cells and Chief Cells

Front 21

What do parietal cells (in gastric glands) produce?

Back 21

Intrinsic Factor &
Hydrochloric Acid (HCL)

Front 22

What is Intrinsic Factor and what does it do?

Back 22

A Glycoprotein that aids in the absorption of vitamin B12

Front 23

What does Hydrochloric Acid (HCL) do?

Back 23

It kills microorganisms, breaks down plant cell walls and connective tissue, and activates the enzyme pepsin

Front 24

What do chief cells produce?

Back 24

Pepsinogen

Front 25

What is pepsinogen converted to and what is it involved with?

Back 25

It is converted to the active form pepsin by HCL and it is involved with the digestion of proteins

Front 26

What do Pyloric glands secrete?

Back 26

Mucus, Gastrin, and Somatostatin (the latter two being hormones)

Front 27

What is gastrin?

Back 27

It is a hormone which controls gastric secretion

Front 28

What is somatosin?

Back 28

A hormone that is produced continuously and inhibits the release of gastrin

Front 29

What three phases control secretions in the stomach?

Back 29

Cephalic Phase, Gastric Phase and the Intestinal Phase

Front 30

Describe the Cephalic Phase (also known as head phase)

Back 30

thought, taste, smell or sight of food stimulates the cerebral cortex/hypothalamus which in turn stimulates the medulla oblongata which also stimulates gastric glands and gastric motility, stimulating the secretion of gastric juice

Front 31

Describe the Gastric (hormonal) Phase of stomach secretion

Back 31

Distention of stomach and rise in pH stimulates the gastric (pyloric) endocrine glands, which stimulate Gastrin, stimulating gastric glands, gastric motility and the secretion of gastric juices

Front 32

Describe the Gastric (nervous) Phase of stomach secretion

Back 32

Distention of stomach and rise in pH stimulates the gastric glands, gastric motility and the secretion of gastric juices

Front 33

Describe the Intestinal (hormonal) phase of the stomach secretion

Back 33

Distention of duodenum/presence of fatty acids glucose stimulate the duodenal endocrine glands which release gastric inhibitory peptide (GIP), secretin and Cholecystokinin (CCK) which inhibit the gastric glands and gastric motility and reduce the secretion of gastric juices

Front 34

Describe the Intestinal (nervous) phase of the stomach secretion (also called the Enterogastric Reflex)

Back 34

Distention of the duodenum/presence of fatty acids glucose stimulate the medulla oblongata which inhibit the gastric glands and gastric motility and reduce the secretion of gastric juices

Front 35

What acts as protection for the stomach lining? 1 of 4

Back 35

Thick coat of mucus containing bicarbonate ions

Front 36

What acts as protection for the stomach lining? 2 of 4

Back 36

Epithelial cells of the mucosa containing many tight junctions

Front 37

What acts as protection for the stomach lining? 3 of 4

Back 37

The apical membranes of the cells within the gastric glands are impermeable to HCL

Front 38

What acts as protection for the stomach lining? 4 of 4

Back 38

Damaged epithelial cells are quickly replaced by stem cells (lining is completely replaced every 3-6 days)

Front 39

What does Pepsin do?

Back 39

It converts proteins into polypeptides

Front 40

What does NOT occur in the stomach as far as digestion and absorption go?

Back 40

Nutrient absorption does not occur, although some drugs such as ethanol and aspirin can be absorbed

Front 41

What types of motility occur in the stomach?

Back 41

Receptive Relaxation
Tonic Contractions
Peristalsis
Control of Gastric Motility

Front 42

Describe Receptive Relaxation

Back 42

Gastric muscles relax as food enters the stomach

Front 43

Describe Tonic Contractions

Back 43

Contractions of the longitudinal smooth muscle layer. (mixes the chyme)

Front 44

Describe Peristalsis

Back 44

Moves Chyme through the stomach

Front 45

What is pancreatic juice produced by and what does it consist of?

Back 45

Acinar Cells. It consists of water, bicarbonate ion and digestive enzymes

Front 46

Describe the control mechanism for the pancreas (1)

Back 46

sight, thought, taste or smell of food stimulates the medulla, which stimulates the pancreas and pumps out the pancreatic juice

Front 47

Describe the control mechanism for the pancreas (2)

Back 47

acids in the duodenum stimulate the duodenal endocrine glands which secrete secretin and CCK, stimulating the pancreas, which pump out the pancreatic juice

Front 48

What are the secretions of the Liver?

Back 48

Bile:
Water
Bile Salts
Bile Pigments
Various Fats: cholesterol, neutral fats and phosholipids
Electrolytes

Front 49

Describe the control of secretion for bile

Back 49

CCK, secretin, gastrin, and parasympathetic NS cause _________ of the gallbladder and the release of bile into the duodenum

Front 50

Describe production of bile and where it is stored

Back 50

Bile is produced constantly (1L/day) and stored in the gallbladder

Front 51

Describe the types of metabolic regulation of the liver

Back 51

Maintains blood glucose levels (90 mg/dl)
Maintains blood triglyceride, fatty acid and cholesterol levels
Removes excess amino acids from the blood
Removes wastes (ammonia), toxins and drugs
Stores Fat soluble vitamins A, D, E, and K
Stores Iron

Front 52

What are Kupffer cells and what do they do?

Back 52

They are antigen presenting cells (APCs) and remove worn out cells, cellular debris and pathogens from the blood by phagocytosis

Front 53

Describe the types of regulation of blood in the liver

Back 53

Synthesis of plasma proteins (albumins, fibrinogen, complement, etc)
Removal of circulating hormones
Removal of antibodies
Removal or storage of toxins

Front 54

What glands secrete mucus for protection of the small intestines lining?

Back 54

Submucosal Glands

Front 55

What glands produce erepsin and carbohydrases?

Back 55

Intestinal Glands

Front 56

What is the control of secretion for the small intestine?

Back 56

mechanical/chemical stimulates the small intestines which stimulate the intestinal glands

Front 57

How are carbohydrates digested in the small intestine?

Back 57

Dextrins are converted to disaccharides by the pancreatic amylase.
The disaccharides are converted to monosaccharides by carbohydrases

Front 58

How are proteins digested in the small intestine?

Back 58

Polypeptides are converted to dipeptides by trypsin, chymotrypsin and carboxypeptidase.
Dipeptides are converted to amino acids by erepsin

Front 59

How are lipids digested in the small intestine?

Back 59

They are converted to emulsified fats by bile. The emulsified fats are then converted to glycerol and fatty acids by pancreatic lipase

Front 60

How are nucleic acids digested in the small intestine?

Back 60

They are converted to nucleotides by pancreatic nuclease

Front 61

Step one of absorption in the small intestine

Back 61

Monosaccharides, amino acids, and nucleotides are actively transported into the blood.

Front 62

Step two of absorption in the small intestine

Back 62

Glycerol and fatty acids diffuse into intestinal cells and combine to form fat, which then diffuse out, become attached to proteins becoming chylomicron which diffuse into lacteals and then blood.

Front 63

Step three of absorption in the small intestine

Back 63

Vitamins diffuse into the blood

Front 64

Step Four of absorption in the small intestine

Back 64

Cations are actively absorbed while anions diffuse into the blood

Front 65

Step five of absorption in the small intestine

Back 65

Water (2L from diet and 7L from digestive juices/day) moves into blood by osmosis

Front 66

Name the types of motility in the small intestine

Back 66

Segmenting Movement
Pendular Movement
Peristalsis
Gastroileal Reflex

Front 67

Describe Segmenting Movement

Back 67

Contractions of the circular muscle layer that segments and mixes the chyme

Front 68

Describe Pendular Movement

Back 68

Contractions of the longitudinal smooth muscle layer that moves and mixes the chyme

Front 69

Describe Peristalsis

Back 69

Moves the chyme through the intestines

Front 70

Describe Gastroileal reflex

Back 70

Ileum contracts moving contents into large intestines

Front 71

What do the large intestines absorb?

Back 71

Actively Absorbs Sodium Ions
Water is absorbed by Osmosis
Vitamins, K, B12, thiamin and riboflavin produced by the bacteria in the gut

Front 72

What are the four types of motility related to the large intestines?

Back 72

Segmenting Movement
Tonic Contractions
Mass Movement
Defecation

Front 73

Describe Mass Movement

Back 73

Strong peristaltic wave that moves feces into the rectum

Front 74

Describe Defecation

Back 74

Rectum stretches as it fills
Stretch receptors are Stimulated, also stimulating peristalsis. Contraction of rectal muscles and the relaxation of the internal sphincter occur, which stimulates the cerebral cortex (voluntary). The relaxation of the externals sphincter and contraction of the diaphragm occur, causing defecation