Digestion

Question 1

Extracellular Digestion

Answer 1

Digestion occurs within cavities.
Ingestion, digestion, absorption assimilation and egestion

Question 2

Alimentary cand extends
from… to …

Answer 2

Mouth to anus

Question 3

Alimentary canal consists of

Answer 3

Oral cavity
Esophagus
Stomach

Small intestine (duodenum,jejunum,ileum)

Large intestine (caecum, colon)

Question 4

Saliva secreted by 3 pairs of salivary glands known as

Answer 4

1. Sublingual glands
2. Sub maxillary glands
3. Parotids glands

Question 5

Sub maxillary glands location

Answer 5

Located behind jaws.
produce saliva with amylase and mucous

Question 6

Parotids glands

Answer 6

Located in front of ears.
Secrete saliva with amylase

Question 7

Sublingual glands location and production

Answer 7

Below the tongue
Produce saliva

Question 8

Saliva composition

Answer 8

99.5% water
PH 8 (alkaline) and after loss of CO2 PH 6
NaHCO3(sodium bicarbonate)

Question 9

digestion in oral cavity steps

Answer 9

selection of food
grinding or mastication
lubrication
digestion

Question 10

peristalsis and antiperistalsis

Answer 10

waves of circular and longitudinal muscles preeceded by a wave of relaxation squeezing the food down the canal

Antiperistalsis food moves from intestine to stomach and maybe mouth. Causes vomitting.

Question 11

heart burn or pyrosis

Answer 11

painful burning sensation in chest due to overeating fatty food, caffeine alcoho, smoking

Question 12

stomach location and appearance

Answer 12

J shaped elastic MUSCULAR BAG
situated BELOW THE DIAPHRAM on the left side of abdominal cavity

Question 13

cardiac sphincter and pyloric sphincter

Answer 13

ring of muscles located at junction bwtween esophagus and stomach

ring of mucle at junction between stomach and duodenum

Question 14

3 types of cells and their secretions in stomach [mucosa layer]
All are EXOCRINE except?

Answer 14

1. Mucous cells secrete mucus (glycoproteins in nature)
2. Pareital cells(oxyntic) secrete HCl.
   > maintain PH2

3.Zymogen cells(cheif cells) secrete pepsinogen[inactive protein]

Only endocrine is g cells that secrete gastrin
Stimulates gastric juice prod.

Question 15

Walls of stomach

Answer 15

Composed of three layers

Outer most layer (sercosa) connective tissue

Middle layer (muscularis) composed of smooth mucles

Inner layer(mucosa) of gastric glands

Question 16

partially digested food is known as?
and its function

Answer 16

(acidic)Chyme stimulates release of secretions from pancreas, liver and duodenal cells.

Question 17

small intestine parts

Answer 17

1.Duodenum (first part 20-25cm)
2.Jujenum (second part 2.4 meters)
3.Ileum

Question 18

role of pancreas (enzyme of pancreatic juice)

Answer 18

enzymes of pancreatic juice;
>Amylase or amylopsin {convert starch to maltose}
>lipase {hydrolyzes fats to fatty acid and glycerol}
>trypsin {splits proteins into polypeptides and peptones}

[it contains sodium bicarbonate which neutralises the chyme coming from stomach]

Question 19

role of liver in digestion

Answer 19

Detoxification and production of bile.

> secretes bile, which is temporarily stored in gall bladder and released into duodenum

[HAS NO ENZYMES]

> bile is green (due to bile pigments formed from the breakdown of heamoglobin)
if bile pigments dont leave and accumulate in blood, it causes jaundice

Question 20

Role of Jujenum[and all enzymes+products]

Answer 20

food undigested in duodenum is digested in jujenum and ileum by a group of enzymes.

ENZYMES SUBSTRATE PRODUCT

amino- polypeptide. dipeptide
Peptidase
Erypsin dipeptide amino acid

Lipase fats fatty acids+glycerol

maltase maltose glucose

lactase lactose glucose+galactose

sucrase sucrose glucose+fructose

Question 21

gastrin hormone in digestion

Answer 21

produced from pyloric region of stomach by G-cells.

stimulus; proteins.
function: secretes pepsinogen and HCl

{more protein=more gastrin secreted=more gastric juice}

Question 22

secretin hormone in digestion

Answer 22

produced from duodenum by S-cells.

stimulus: entry of acidic chyme in duodenum

Function:
>stimulates bicarbonate-rich pancreatic juice, which helps neutralize the acidic chyme.

> produce *bile rich in bicarbonate,
which further helps in neutralizing the acid in the chyme.

> Inhibit Gastric Secretion

Question 23

large intestine composition.

Answer 23

Caecum: first part. finger like projections arise known as appendix.
>inflammation of appendix called appendicitus

Colon:divided into four parts.
>ascending colom.travels up the right side of abdomen
>transverse colon:runs across abdomen
>descending colon down the left side of colon
>sigmoid colon: short curve before the rectum.

[Removes water, salt and some nutrients, forming a stool.]
[Diarrhea occurs when water and salts arent absorbed]
[constipation occurs when they are excessively absorbed]

Rectum: defecation reflex

Question 24

Chemical digestion and mechanical

Answer 24

Chemical involves secretion of enzymes that break chemical bonds and hold food particles together.
Amylase in saliva[oral cavity]
Gastric juice in stomach
Pancreatic juice in small intestine

Mechanical is purely physical such as mastication by teeth for oral cavity
Churning by muscles in stomach

Question 25

Teeths used for grinding, tearing food in oral cavity (2)

Answer 25

Molars grinddd
Canines tear

Question 26

Ileum of small intestine function

Answer 26

Nearly all products of digestion takes place here.
Ileum has many inner folds called villi supplied with blood vessels and lymphatic system which make surface area for dissusion of simple sugars and amino acids possible

Question 27

Functions of components of large intestine

Answer 27

1. Caecum: first part. involved in absorbing fluids and salts remained after small intestine digestion and absorption.
2. Colon: Absorbs water, electrolytes and vitamins fromm indigestible food matter and converts it into a stool(tatti)
3. Rectum stores stool before defacation reflex

Question 28

Epiglottis

Answer 28

Leaf shaped flap in throat that prevents food from entering windpipe and lungs