Digestive System - Part 1

Front 1

What is the ALIMENTARY CANAL?

Back 1

also known as the DIGESTIVE TRACT / GUT / Gastrointestinal Tract (GIT)
- it is the hollow tube from mouth
to anus
- considered to be external to the body
- relaxed is 9 meters long
- digests & absorbs food

Front 2

Name 3 main ACCESSORY Organs

Back 2

Pancreas
Gall Bladder
Liver

Front 3

Name 3 sub-accessory organs

Back 3

Teeth
Tongue
Salivary Glands

Front 4

Name the 6 ORGANS OF THE ALIMENTARY CANAL

Back 4

- mouth
- pharynx
- oesophagus
- stomach
- small intestine
- large intestine - this leads to the terminal opening (anus)

Front 5

What is SALIVA's PROTECTION function?

Back 5

- cleanses the mouth
- 1st line of chemical digestion (enzym Amylas breaks down starch)
- moistens food
- dissolving food to taste

Front 6

What is INGESTION?

Back 6

Taking food into the digestive tract via the mouth

Front 7

What is MASTICATION?

Back 7

chewing / mechanical digestion

Front 8

What is DEGLUTITION?

Back 8

Swallowing

Front 9

What is PERISTALSIS?

Back 9

(involuntary) Muscular contractions & relaxation that follows a direction

Front 10

What is MECHANICAL digestion?

Back 10

Physically prepares food for chemical digestion by enzymes. Mouth - chewing

Front 11

What is a MECHANORECEPTOR

Back 11

Stimulate smooth muscle of the GI tract walls to mix LUMEN (an opening) contents and move them along the tract, : Stomach - stretch sends message to brain saying "I am full"

Front 12

What is a CHEMORECEPTOR

Back 12

Located in the walls of the GI tract organs: Chemical messages, Ph in Stomach - eg: is more needed?, etc like digestive juices into the LUMEN or hormones into the blood

Front 13

What is PROPULSION?

Back 13

moves food through the ALIMENTARY canal, includes swallowing which is initiated voluntarily (peristalsis)

Front 14

What is CHEMICAL digestion?

Back 14

complex food molecules are broken down to their chemical building blocks by enzymes secreted into the LUMEN of the alimentary canal. Begins in the mouth and essentially complete in the small intestine.

Front 15

What is ABSORPTION?

Back 15

is the passage of digested end products (plus vitamins / minerals / water) from the LUMEN of the GI tract through the MUCOSA cells by active or passive transport into the blood or lymph.
THE SMALL INTESTINE IS THE MAJOR ABSORPTION SITE.

Front 16

What is DEFECATION?

Back 16

eliminates indigestible substances from the body via the anus in the form of feces.

Front 17

TRUE or FALSE
Does the digestive system monitor itself independently of the nervous system?

Back 17

TRUE

Front 18

List the ORDER of digestion

Back 18

- Ingestion (food into mouth)
- Mechanical digestion (chewing <segmentation>)
- Propulsion (swallowing <oropharynx> & Peristalsis <esophagus, stomach, small intestine, large intestine>
- Chemical digestion (stomach)
- Absorption (small intestine - lymph & blood vessels)
- Large intestine
- Defecation (terminal opening <anus>)

Front 19

What is the GUT's BRAIN?

Back 19

nerve plexuses, entire length of gut

Front 20

What is SHORT REFLEXES?

Back 20

STIMULI ARISES FROM WITHIN THE GIT

Front 21

What is LONG REFLEXES?

Back 21

- Intrinsic & extrinsic stimuli
- Involves CNS (autonomic)

Front 22

Identify the LOCATION of the SALIVARY GLANDS

Back 22

- parotid gland
- sublingual gland
- submandibular gland

Front 23

How is salivation controlled?

Back 23

primarily by the parasympathetic division of the ANS. when we ingest food chemoreceptors & mechanoreceptors in the mouth send signals to the salivatory nuclei in the brain stem

Front 24

What are CHEMORECEPTORS most strongly activated by?

Back 24

Acidic substances like vinegar / citrus juices

Front 25

What are MECHANORECEPTORS most strongly activated by?

Back 25

virtually any mechanical stimulus in the mouth

Front 26

If the stomach is full of acid - why does it not EAT itself?

Back 26

At the top of the gastric pit, we have mucous

Front 27

What is the stomach PH?

Back 27

Ph 1-2 VERY ACIDIC

Front 28

Name the 3 stomach muscles

Back 28

- Longitudinal layer
- Circular layer
- Oblique layer

Front 29

Describe the GROSS STRUCTURE of the stomach

Back 29

Top of the stomach is close to the heart, the cardiac sphincter stops the food from going back up, it can be held in the stomach by the pyloric sphincter.

Front 30

Name the 5 SECRETIONS of the stomach

Back 30

- hydrochloric acid (HCI)
- Pepsinogen
- Lingual Lipase
- Intrinsic Factor
- Enteroendocrine cells

Front 31

State the FUNCTION of HYDROCHLORIC ACID

Back 31

- secreted by Parietal cells
- extremely acidic
- denatures dietary proteins
- kills bacteria

Front 32

State the FUNCTION of PEPSINOGEN

Back 32

- secreted by chief cells which is the inactive form of Pepsin
- most important protein digesting enzyme
- once Pepsin is present, it also catalyses the conversion of Pepsinogen to Pepsin

Front 33

State the FUNCTION of LINGUAL LIPASE

Back 33

- released by the intrinsic salivary glands
- may digest some triglycerides (type of fat found in your blood) in the stomach

Front 34

State the FUNCTION of INTRINSIC FACTOR

Back 34

- secreted by Parietal cells (stomach epithelium cells)
- is required for intestinal absorption of vit B12
- needed to produce erythrocytes (red blood cells)

Front 35

State the FUNCTION of ENTEROENDOCRINE CELLS

Back 35

- release a variety of chemical messenges into the interstitial fluid
- histamine & serotonin & gastrin (a hormone that plays essential roles in regulating stomach secretion & motility {move spontaneously & consume energy})

Front 36

Describe the 3 phases of GASTRIC SECRETION

Back 36

- CEPHALIC PHASE : NO FOOD IN SYSTEM; using brain not stomach
(sight & thought of food, stimulation of sight & smell receptors)
- GASTRIC PHASE : FOOD IN STOMACH; getting ready to receive food, stomach starts stretching (stomach distension activates stretch receptors, food chemicals {especially peptides & caffeine} & rising pH activate chemoreceptors
- INTESTINAL PHASE : STARTING TO PUT FOOD INTO INTESTINE; arrive 1st part of small intestine, (presence of low pH, partially digested foods, fats or hypertonic solution in DUODENUM when stomach begins to empty

Front 37

List the CELLS of the STOMACH

Back 37

- Mucosus neck Cells
- Parietal Cells
- Chief Cells
- Enteroendocrine Cells

Front 38

What do the Mucosus Cells of the STOMACH secrete?

Back 38

- Mucosus Neck Cell
produce a thin, soluble mucus

Front 39

What do the Parietal Cells of the STOMACH secrete?

Back 39

- Parietal Cells
secrete HCl which makes the stomach contents extremely acidic, necessary for activation & optimal activity of PEPSIN, it also helps food digestion by denaturing proteins and is harsh enough to kill bacteria. It also secretes Intrinsic factor, which is a glyco protein required for vitamin B12 absorption in the small intestine.

Front 40

What do the Chief Cells of the STOMACH secrete?

Back 40

- Chief Cells
produce PEPSINOGEN, the inactive form of the protein-digesting enzyme PEPSIN.

Front 41

What do the Enteroendocrine Cells of the STOMACH secrete?

Back 41

- Enteroendocrine Cells
release a variety of chemical messengers directly into the interstitial fluid. Examples, HISTAMINE, SOMATOSTATIN, GASTRIN

Front 42

What is the CEPHALIC Phase?

Back 42

sight & thought of food, stimulation of taste & smell receptors

Front 43

What is the GASTRIC Phase?

Back 43

stomach distension activates stretch receptors, food chemicals & rising pH activate chemoreceptors

Front 44

What is the INTESTINAL Phase?

Back 44

presence of low pH, partially digested foods, fats or hypertonic solution in duodenum when stomach begins to empty.

Front 45

Explain how gastric activities (gastric, motility & emptying) are regulated.

Back 45

Stomach contractions not only accommodate its filling and cause emptying, but they also compress, knead & continually mix the food with gastric juice to produce chime.

Front 46

Is SEROTONIN more prevalent in the brain or stomach?

Back 46

stomach

Front 47

When does RECEPTIVE RELAXATION occur?

Back 47

in both anticipation of and in response to food movement through the oesophagus and into the stomach; the process is coordinated by the swallowing centre of the brain stem & mediated by the VAGUS nerves acting on serotonin.

Front 48

What is GASTRIC ACCOMMODATION an example of?

Back 48

it is an example of smooth muscle plasticity; to be stretched without greatly increasing its tension.

Front 49

What does GASTRIC CONTRACTILE ACTIVITY exhibit?

Back 49

in the oesophagus, the stomach exhibits PERISTALSIS. Normally each "wave" squirts 3ml or less of CHYME into the small intestine.

Front 50

Describe the REGULATION of GASTRIC EMPTYING

Back 50

- the stomach usually empties completely within FOUR hours after a meal;
- fluids pass quickly through; solids linger, remaining until they are well mixed with gastric juice & converted to a liquid state;
- gastric emptying depends mostly on the contents of the DUODENUM;
- the stomach & duodenum act in tandem; as chyme enters the DUODENUM, receptors in its wall respond to chemical signals & to stretch, initiating the enterogastric reflex & hormonal mechanisms that inhibit acid & pepsin secretion.
- when chyme entering the DUODENUM is fatty, food may remain in the stomach 6 hours or more.

Front 51

The enzymatic breakdown of any type of food molecule in water is called

Back 51

hydrolysis

Front 52

The terminal portion of the small intestine is known as the

Back 52

ileum

Front 53

You have just eaten a meal high in complex carbohydrates. Which of the following enzymes will help to digest the meal?
a. amylase
b. cholecystokinin
c. gastrin
d. trypsin

Back 53

a. amylase

Front 54

which BRANCH of the ANS is most important to GASTRIC ACTIVITY?

Back 54

Parasympathetic