git

Question 1

accessory glands of GIT?

Answer 1

teeth, tongue, salivary

glands, liver, gallbladder, pancreas

Question 2

Digestive tract

Answer 2

Open at both ends and continuous with 
the environment
– Considered “outside” the body
– Materials that cannot be digested (cellulose) 
never actually “enter” the body

Question 3

Structure of the Gastrointestinal Tract Wall

Answer 3

it has four layers;
1.Mucosa
lamina propia
muscularis mucosa
epithelium(with exocrine, endocrine and mucous cells)

2.submusosa
major blood and lymphatics vessels
submucosal plexus
3.muscularis externa
circular muscle
myenteric pexus
longitudinal muscles
serosa

Question 4

GI Tract Layers

Answer 4

• Also called tunics
• There are four tunics:
1. Mucosa: inner secretory and absorptive
layer; may be folded to increase surface area

2. Submucosa: very vascular, to pick up
   nutrients; also has some glands
3. Muscularis: smooth muscle; responsible for
   peristalsis and segmentation
4. Serosa: outer binding and protective layer

Question 5

primary fubction of digestive tract

Answer 5

From food, humans must get basic organic
molecules to make ATP, build tissues, and
serve as cofactors (Zn, Mg) and
coenzymes (NADH, FADH).
– Digestion breaks polymers (carbohydrates,
fats, and proteins) into monomer building
blocks.
– Absorption takes these monomers into the
bloodstream to be allocated

Question 6

digestive tract motility function

Answer 6

Motility
– Ingestion: taking food into the mouth
– Mastication: chewing
– Swallowing: food moves from mouth into
stomach
– Peristalsis: one-way movement through tract
– Segmentation: churning/mixing

Question 7

volume of secretions of fluids

Answer 7

salivary secretion=pancreatic secretion=intestinal secretion- 1500 mL
2000mL gastric secretion

Question 8

amount of bile produced

Answer 8

500mL

Question 9

how much is absorbed in small intestine

Answer 9

6700mL

Question 10

how much is absorbed in large intestine

Answer 10

1400mL

Question 11

regulation food intake(feeding behaviour)

Answer 11

it involves 3 hypothalamic nuclei(is a portion of of the brain that contains number of small nuclei with variety of function)
1. Lateral hypothalamus nuclei-regulates feeding
which means it can increase/decrease food intake
if this nuclei is removed you will have no desire to eat
once you are full your GIT will sense chemical being released, blood nutrient which have increased in your blood and distention which will stimulate the satiety center

2.Ventromedial nucleus(satiety center)
This center has inhibitory effect on lateral hypothalamus and prevent food intake(it makes you feel like you have taken enough amount of food)

3. Arcuate nuclei(it controls ventromedial nucleus)

Question 12

Primary Peristalsis

Answer 12

contraction of pharyngeal muscles; wave of
contraction, followed by the wave of relaxation of muscle fibers of
GI tract which travel away from the mouth.

Question 13

Secondary peristalsis

Answer 13

induced by distention of esophagus

Question 14

• Swallowing occurs in three stages:

Answer 14

• I. Oral stage, when food moves from 
mouth to pharynx
• II. Pharyngeal stage, when food moves 
from pharynx to esophagus
• III. Esophageal stage, when food moves 
from esophagus to stomach, regulated by 
Upper and lower esophageal sphincters

Question 15

Oral phase: 1 sec

Answer 15

Initiates swallowing process tongue pushes the bolus of
food to the back of the hard palate, pharynx/throat to
stimulate the sensory (oropharyngeal) receptors in
pharynx - initiate the swallowing reflex- this result in
peristalsis.
These receptors send afferent impulses (via vagus,
glossophyrangeal, trigeminal nerves) to the swallowing
center in the medulla oblongata. This center then elicits
swallowing via efferent impulses to the muscles in the
pharynx (glossophyrangeal nerve) and esophagus (vagus
nerve)

Question 16

Pharyngeal phase: 1-2 sec

Answer 16

• Tongue against soft palate prevent return of bolus back
into mouth
• Soft palate move upward prevent bolus into nasal
cavity/ nasopharynx
• Stimulates larynx movements, cause epiglottis to closed
airways and upper esophageal sphincter (UES) to
open ONE WAY
• Peristalsis is produced by pharyngeal muscles and move
bolus into esophagus
• Swallowing apnea: All these movements arrest
respiration for a few seconds

Question 17

Esophageal phase:

Answer 17

• Begins with relaxation of the UES and continuation of
peristalsis (primary) produced in the pharyngeal stage to
propel bolus into the stomach.
• The lower esophageal sphincter (LES) opens and remains
relaxed throughout the period of swallowing, allowing the
arriving food to enter the stomach.
• Secondary peristalsis: induced by distention of esophagus
• LES closes/constricts after food passes into stomach,
resealing the junction between the esophagus and the
stomach

Question 18

Secretion

Answer 18

– Exocrine: digestive enzymes, acid, mucus

– Endocrine: hormones to regulate digestion

Question 19

Digestion

Answer 19

– Breaking food down into smaller units

Question 20

Absorption

Answer 20

– Passing broken-down food into blood or lymph

Question 21

Saliva functions

Answer 21

Lubrication and binding
• Initiates carbohydrate digestion
• Oral hygiene: Flow of saliva decreases during sleep
allowing bacteria to build up in mouth

Question 22

functions of Saliva

Answer 22

Washes mouth - secretion rate 0.5 ml/min
• Destroys bacteria - proteolytic enzymes (lysozyme)
- thiocyanate
- antibodies
• Xerostomia (dry mouth) - (absence of saliva)

Question 23

Storage and elimination

Answer 23

Temporary storage and elimination of

undigested food

Question 24

Immune barrier

Answer 24

Simple columnar epithelium with tight
junctions prevents swallowed pathogens
from entering body

Question 25

regulation of the GIT

Answer 25

1. Autonomic system: • Sympathetic division: – Inhibits peristalsis and secretion – Stimulates contraction of sphincters • Parasympathetic nerves: – Stimulates motility and secretions via vagus nerve in esophagus, stomach, small intestine, pancreas, gallbladder, and upper portion of large intestine 2.Hormones: – digestive organs 3. Intrinsic regulation: – Intrinsic sensory neurons in gut wall help in intrinsic regulation via separate enteric nervous system (ENS) – ENS: Myenteric plexus (Auerbach’s plexus) Submucosal plexus (Meissner’s plexus)

Question 26

How are Gastrointestinal Processes | Regulated?

Answer 26

Control mechanisms of the gastrointestinal system are governed by the volume and composition of the luminal contents, rather than by the nutritional state of the body. • This means that the body is designed to absorb all the nutrients that are ingested, whether or not the body really needs them to function

Question 27

Enteric nervous system

Answer 27

Substance P: Stimulatory Achetylcholine: stimulatory NO:nitric oxide: inhibition VIP, vasoactive intestinal peptide: inhibition

Question 28

Ek yielding nutrient

Answer 28

Fat • Carbohydrates • Protein

Question 29

None caloric nutrients

Answer 29

* H2O * Vitamins * Minerals

Question 30

Tissues have preferred energy sources.

Answer 30

– Brain: glucose – Red blood cells (erythrocytes): glucose, lacks mitochondria – Skeletal muscles at rest: fatty acids However, when muscle contraction is required for a very short burst of activity, the exercising muscles make use of the intracellular ATP pool

Question 31

Fats vs Sugars

Answer 31

• Carbohydrates are the body’s preferred fuel • Sugars are a quicker source of energy because they are more soluble in water • Triacyclglycerols are the primary energy storage molecules • Fats yield more energy than sugars

Question 32

Essential Nutrients | • There are nine essential amino acids:

Answer 32

Lysine, tryptophan, phenylalanine, threonine, | methionine, leucine, isoleucine, and histidine

Question 33

• There are two essential fatty acids:

Answer 33

– Linoleic acid (an omega-6) | – Linolenic acid (an omega-3)

Question 34

small intestine structure

Answer 34

``` Three sections: – Duodenum – Jejunum – Ileum • Mucosa and submucosa folded into into villi; and epithelial plasma membranes folded into microvilli ```

Question 35

Absorption in the Small Intestine

Answer 35

• The small intestine is anatomically arranged for a large surface area, which enhances the absorption of nutrients. • One of the specialized anatomical structures is the Villi. Villi increase surface area and contain blood vessels and lacteal, which play a role in the absorption of nutrients. • Another specialized structure is the microvilli. Microvilli increase surface area and form the brush border

Question 36

Villi and Microvilli

Answer 36

• Columnar epithelium with goblet cells (mucus) • Blood vessels/Capillaries absorb sugars and amino acids, and lacteals absorb fatty acids. • Intestinal crypts with Paneth cells (secrete antibacterial molecules) and mitotic stem cells-enterocytes

Question 37

Small Intestine Functions

Answer 37

``` • Complete digestion of carbohydrates, proteins, and fats • Absorption of nutrients – Sugars, lipids, amino acids, calcium, and iron absorbed in duodenum and jejunum – Bile salts, vitamin B12, water, and electrolytes in ileum – Very rapid due to villi and microvilli ```

Question 38

Intestinal Contractions/Motility

Answer 38

• Peristalsis is weak. Movement of food is much slower due to pressure at pyloric end. • Segmentation is stronger and serves to mix the chyme.

Question 39

Large Intestine Function

Answer 39

• Absorption of water, electrolytes, vitamin K, and some B vitamins • Production of vitamin K and B vitamins via microbial organisms • Storage of feces

Question 40

The Hepatic Portal System

Answer 40

is a specialized vasculature that delivers absorbed nutrients to the liver for processing before they enter the general systemic circulation. • Nutrients are absorbed from the small intestine into mesenteric veins which then carry them to the liver via the hepatic portal vein

Question 41

the liver

Answer 41

The liver serves as a secretory organ. One of its major functions is to secrete bile. • The liver also processes and stores nutrients. • The liver also serves as a filter and functions in the removal of old red blood cells which leads to hemoglobin processing and the generation of bilirubin. • The liver is also responsible for the synthesis of plasma proteins (albumin, clotting proteins, angiotensinogen, steroid binding proteins)

Question 42

trypsin, eleptase and chymotrypsin

Answer 42

proteins that break peptide bonds into peptide fragment

Question 43

carboxypeptidase

Answer 43

protein that splits off terminal amino acids from carboxyl end of protein

Question 44

lipase

Answer 44

splits off two fatty acids from triglycerides forming free fatty acids and monoglycerides

Question 45

amylase

Answer 45

Amylase is a protein made by your pancreas and by glands in and around your mouth and throat. It helps you break down carbohydrates and starches into sugar

Question 46

deoxy/ribonuclease

Answer 46

nucleic acids that splits nucleic acids into free nucleotides

Question 47

pancrease

Answer 47

The pancreas has both exocrine and endocrine functions. • The exocrine portion produces “pancreatic juice.” This is rich in bicarbonate as well as digesting enzymes.

Question 48

phases of regulation

Answer 48

cephalic gastric intestinal phase

Question 49

cephalic phase of regulation

Answer 49

1.sight, smell and taste of food cause stimulation of vagus nuclei in brain 2.Vagus nuclei stimulates acid secretion indirect stimulation of parietal cells(major effect) stimulation of gastrin secretion(lesser effect)

Question 50

Gastric phase of regulation`

Answer 50

Distention of stomach stimulates vagus nerve,vagus stimulates acid secretion 2. Amino acids and peptides in stomach lumen stimules acid secretion(lesser effect) - Indirect stimulation of parietal cells(lesser effect) - Stimulation of gastrin secretion; gastrin stimulates acid secretion (major effect) 3. Gastrin secretion inhibited when pH of gastric juice falls below 2.5

Question 51

intestinal phase of regulation

Answer 51

Neural inhibition of gastric emptying and acid secretion - Arrival of chyme in duodenum causes distention, increase in osmotic pressure - These stimulate activate a neural reflex that inhibits gastric activity 2. In response to fat in chyme, duodenum secretes a hormone that inhibits gastric acid secretion

Question 52

carbohydrates

Answer 52

Most carbohydrates in the diet are consumed as disaccharides or polysaccharides: – Sucrose – Lactose – Maltose – Starch – Glycogen – Cellulose • Only monosaccharides are absorbed by the intestinal cells for use in the body. • Disaccharides and polysaccharides must be digested to monosaccharides before they can be absorbed for use in the body.

Question 53

proteins

Answer 53

Proteins are broken down to peptide fragments in the stomach by pepsin, and in the small intestine by trypsin and chymotrypsin, the major proteases secreted by the pancreas. • These fragments are further digested to free amino acids by carboxypeptidase from the pancreas and aminopeptidase, located on the luminal membranes of the small intestine epithelial cells. • The free amino acids then enter the epithelial cells by secondary active transport coupled to Na+. • Short chains of two or three amino acids are also absorbed by a secondary active transport coupled to the hydrogen ion gradient

Question 54

vitamins

Answer 54

Fat-soluble vitamins (A, D, E, and K) are absorbed like other lipids. • Water-soluble vitamins are absorbed by diffusion or mediated transport, except for vitamin B12, which must first bind to a transport protein known as intrinsic factor

Question 55

production of HCL

Answer 55

Drops pH to 2 – Proteins are denatured (allows enzymes access). – Pepsinogen is converted to active pepsin (digests proteins). – Serves as the optimal pH for pepsin activity

Question 56

stomach defenses

Answer 56

Acid and pepsin could eat the stomach lining. • Defenses that help prevent this: – Adherent layer of mucus with bicarbonate – Tight junctions between epithelial cells – Rapid epithelial mitosis that replaces epithelium every three days

Question 57

digestion and absorption in the stomach

Answer 57

• Proteins begin digestion in the stomach. – Starches begin digestion in the mouth, but salivary amylase is not active at pH 2, so this activity stops in the stomach. • Alcohol and non-steroidal anti inflammatory drugs (NSAIDs, eg. aspirin) are the only common substances absorbed in the stomach (due to high lipid solubility).

Question 58

functions of saliva

Answer 58

Moistens and lubricates food (facilitates swallowing) Initiates very small amount of digestion of polysaccharides by amylase (described in detail later) Dissolves a small amount of food (which facilitates taste) Kills bacteria and other pathogens (helps maintain gum and tooth health) Secretes HCO, "(neutralizes ingested acidic foods and thereby protects tooth enamel and the lining of the esophagus)

Question 59

secretions and functions of mouth and pharynx related to absorption and digestion

Answer 59

function:Chewing begins initiation of swallowing reflex

Question 60

secretions and functions of salivary glands related to absorption and digestion

Answer 60

Moisten and dissolve food: help neutralize ingested acid ( secretion: :lons and water) Lubrication (mucus) Polysaccharide-digesting enzyme (relatively minor function) (amylase) Help prevent tooth and gum decay( antibodies and other immune factors)

Question 61

secretions and functions of oesophagus related to absorption and digestion

Answer 61

Move food to stomach by peristaltic waves. Lubrication(secretion: mucus)

Question 62

secretions and functions of stomach related to absorption and digestion

Answer 62

Store, mix, dissolve, and continue digestion of food; regulate emptying of dissolved food into small intestine Solubilization of some food particles; kill microbes, activation of pepsinogen to pepsin (HCL) Begin the process of protein digestion in the stomach(Pepsin) Lubricate and protect epithelial surface(Mucus)

Question 63

secretions and functions of pancreas related to absorption and digestion

Answer 63

Secretion of carymes and bicarbonate: also has nondigestive endocrine functions Digest carbohydrates, fats, proteins, and nucleic acids (enzymes) Neutralize HCI entering small intestine from stomach (Bicarbonate)

Question 64

secretions and functions of liver related to absorption and digestion

Answer 64

Organic waste products and trace metal Secretion of bile Solubilize water-insoluble fats (Bile salts) Neutralize HCI entering small intestine from stomach( Bicarbonate) Elimination in feces ( Organic waste products and trace metals)

Question 65

secretions and functions of gall bladder related to absorption and digestion

Answer 65

Store and concentrate bile between meals

Question 66

secretions and functions of small intestine related to absorption and digestion

Answer 66

Digestion and absorption of most substances; mixing and propulsion of contents Digestion of macromolecules (enzymes) Maintain fluidity of haminal contents (Ions and water) Lubrication and protection (Mucus)

Question 67

secretions and functions of large intestine related to absorption and digestion

Answer 67

Storage and concentration of undigested matter, absorption of ions and water, mixing and propulsion of contents; defecation Lubrication (Mucus)