digestive system(advanced)

Question 1

What is the digestive system?

Answer 1

The digestive system or the digestive
tract.

This like tube some nine meter in total
through the middle of the body. Its
start at the mouth where the food an
drink enter the body and finished at
the anus where the food and waste
leave the body.

Question 2

What are the main parts of the digestive system?

Answer 2

➢ The mouth (buccal cavity)
➢ Esophagus
➢ Stomach

➢ Small intestine (duodenum-jejunum-
ileum

➢ Large intestine(caecum-colon-rectum)-
Auns.

Question 3

What are the accessory glands?

Answer 3

➢ Salivary gland

➢ Liver

➢ Pancreas.

Question 4

What is the buccal cavity?

Answer 4

The buccal cavity or oral cavity is entrance
to the digestive tube , it contain:
The tongue, the teeth and the two lips.
In the mouth cavity the major and minor
salivary gland open by difference duct.

Question 5

How does teeth act and what are the basic secretary units?

Answer 5

Teeth bite off and chew food into a soft pulp
that is easy to swallow, chewing mixes the
food with watery saliva from salivary gland,
to make it moist.
The basic secretary units of salivary gland
are water, mucus and enzymes which flow
out through collecting ducts to the mouth.

Question 6

What are the major salivary glands?

Answer 6

➢Parotid gland (which found in front of both
ears) which secreted water at the buccal
cavity.
➢Submandibular glands (which found inner
to the mandible) these glands produce
mucus secretion.
➢Sublingual glands (which found under the
tongue) these glands secreted saliva.

Question 7

What are the important functions of saliva?

Answer 7

• Lubricates and moistens the buccal mucosa and
  lips.
• It washes the mouth cavity from the food debris.
• It transforms the food into a semi-solid mass in
  order to be swallowed and to be tasted easily.
• Saliva helps digestion of certain food because it
  contains glycoprotein and maltase enzymes,
  thus saliva initiates starches and
  polysaccharides digestion

Question 8

What is the esophagus?

Answer 8

Is the long muscular tube, its lining
membrane of compound epithelium is very
much folded and at the opening-leading
pharynx. Food passes through the
esophagus using the process
PERISTALSIS( the mechanism of
movement of food inside the esophagus)
which extends through the chest and
diaphragm to reach stomach.

Question 9

What is the stomach?

Answer 9

The stomach is an expanded section of the
digestive tube between the esophagus
and small intestine. It has an ovoid shape
and lies inside the abdominal cavity. The
esophagus enters the stomach at its wider
portion, the cardiac portion. The most
distal and narrow section of the stomach is
termed pylorus as food is liquefied in the
stomach it passes through the pyloric
canal into the small intestine.

Question 10

What are the functions of the contents of the stomach?

Answer 10

• The function of oxyntic cells is secrete
  HCL acid.
• The function of peptic cells is produce
  enzyme such as (pepsin).
• The function of columnar cells is
  Absorption of liquids.
  The main function of stomach are:-
• Digestion of food.
• Store of food.
• Kill the pathogens by HCL.
• Absorption of liquids such as water and
  alcohol and medicine

Question 11

What is the small intestine?

Answer 11

Following the stomach comes the longest
section of the digestive tube which consist
(duodenum, jejunum, and ileum).
Duodenum:-
A short section that takes the form u-or C
shaped.
Duodenum receives secretions from the
pancreatic duct into the distal limb and the
bile duct opening beginning of the
duodenum.Following the duodenum the rest of small
intestine (jejunum 8 feet and ileum 12 feet)
The small intestine which is the longest part
of the alimentary canal and forms of loop
and coils.
The main function of small intestine is
ABSORPTION OF DIGESTED FOOD.

Question 12

What are the functions of the contents of the small intestine?

Answer 12

❖Function of Crypts of lieberkuhn is
secretion water mainly and secrete
alkaline fluids to neutralize the acidity of
the chyme.
❖Function of the goblet cells is secretion
mucus which prevent auto-digestion .
❖The function of columnar cells is
Absorption of digested food.
❖ Function of the lymphatic vessel (lacteal)
is absorption of fatty acids

Question 13

What is the large intestine?

Answer 13

This formed of Caecum, colon and rectum.
Caecum:
Is recognized by its large size, most of its
thin walled end by a thick walled much
narrower and finger- like, vermiform
appendix.

Question 14

What is the colon?

Answer 14

Is Sacculated (to delay passage of food ) and lead
into the narrower rectum.
Any useful substances in the leftovers, such as
water and body minerals, are absorbed through
the walls of the large intestine, back into the
blood.
Therefore the main function of large intestine is
Reabsorption of water. The remains substance
are formed into brown, semi-solid (feces) ready
to be removed from the body.

Question 15

What is the rectum and the anus?

Answer 15

The end of the large intestine , the rectum,
its function is to store the feces. These are
finally squeezed through a ring muscle,
(the anus) and out of the body.

Question 16

What is digestion?

Answer 16

Digestion is the breakdown of large
substances into small parts, these
changes are brought out by organic
catalysts known as enzymes. This process
takes place in the digestive system.
Digestion is usually divided into mechanical
and chemical action, and the digestion
separated into five separated processes:- ingestion, mechanical digestion, chemical digestion, absorption and elimination.

Question 17

What is ingestion?

Answer 17

• Ingestion: placing food into mouth .

Question 18

What is mechanical digestion?

Answer 18

• Mechanical digestion: Mastication; the use
  of teeth to tear and crush food and
  movement of food by the muscles of the
  stomach.

Question 19

What is chemical digestion?

Answer 19

• Chemical digestion: Addition of the
  chemical (acid,bile,enzymes and water) to
  breakdown complex molecules into simple
  molecules.

Question 20

What is absorption?

Answer 20

• Absorption: movement of nutrients from
  the digestive system to circulatory and
  capillaries through Osmosis and active
  transport, and diffusion.

Question 21

What is elimination?

Answer 21

• Elimination: removal of undigested
  material from the digestive system through
  defecation.

Question 22

What is hydrolysis?

Answer 22

Digestion consists of a process of
hydrolysis during which the molecular
size of the substances progressively
reduced until a true solution is possible.
These changes are brought out by organic
catalysts knows as enzymes.

Question 23

How do enzymes have specificity?

Answer 23

Each particular enzyme act only upon
particular substance or group of substances
called substrate, and the end of the reaction
it self remain unchanged.

Question 24

What are the conditions of enzymes?

Answer 24

Enzyme can be rendered in active or killed
by heat and others they act best at
particular temperature called optimum
temperature and require that the medium
in which they work shall have a certain
alkalinily or acidity( pH value).

Question 25

What are enzymes classified into?

Answer 25

❖Amylolytic enzymes digest carbohydrates. ❖Proteolytic work on proteins. ❖Lipolytic enzymes act on fats.

Question 26

Where does most absorption take place?

Answer 26

very little absorption of digested food takes place either in the buccal cavity or stomach certain drugs and alcohol may be absorbed in the stomach , the greater part of the absorption take place in the jejunum and ileum where digestion completed the food will pass through the walls into the capillary blood vessels by absorption .

Question 27

Where do digested carbohydrates, lipids, and proteins get absorbed?

Answer 27

the digested carbohydrates (glucose) and proteins (amino acid ) are absorbed by the blood vessels while the fats (fatty acid) is absorbed by lymphatic vessels (lacteal)..

Question 28

What does the liver act as?

Answer 28

The liver besides acting as a regulator also acts a store house for carbohydrates. The amino acid which form the basis for elaborating the body proteins, are liberated in suitable quantities into blood stream, but any excess is subjected in the liver to the process of deamination to form harmless substance, urea into other product, which can inter the glycolytic cycle.

Question 29

What are the intestinal enzymes?

Answer 29

the inner wall of the small intestine is cover by millions of tiny finger like projection called villi. The villi covered with even tinier projection called microvilli. It secreted alkaline watery fluid containing must important enzymes, but also containing mucus. This enzymes complete the various digestive processes of all kind of food substances.

Question 30

Where does digestion begin?

Answer 30

Digestion begins in the buccal cavity, where chemical and mechanical digestion occurs. The food is chewed with teeth, the process stimulate salivary gland produced saliva. Saliva begins to break down food, moistening it and make it easier to swallow, saliva which usually contains enzymes (amylolytic enzyme) this act on certain polysaccharides or starches turning them into compound sugars such as dextrin and maltose.

Question 31

How does digestion proceed down the throat?

Answer 31

Digestion begins in the buccal cavity, where chemical and mechanical digestion occurs. The food is chewed with teeth, the process stimulate salivary gland produced saliva. Saliva begins to break down food, moistening it and make it easier to swallow, saliva which usually contains enzymes (amylolytic enzyme) this act on certain polysaccharides or starches turning them into compound sugars such as dextrin and maltose.

Question 32

How does digestion occur in the stomach?

Answer 32

In the stomach the food is subjected to the action of the gastric juice, the flow of which is included by the hormone gastric secreted by gastric gland. The secretion of gastric juice also promoted by appetite. These responses are mediated by the nerves system. The chemical nature of the food also act directory on the gastric mucosa as also does presence of any food in the stomach by stimulating it mechanical by contraction and relaxation of the muscles(L.M.L,C.M.L).

Question 33

What does gastric juice contain?

Answer 33

In this juice which contains 90% water, two enzymes are usually present, pepsin and rennin. Pepsin is the proteolytic enzyme acting upon protein and reducing them to peptones {polypeptide}. Rennin are is a proteolytic enzyme its rule in digestion is to coagulate milk in the stomach longer periods in the stomach for initial digestion of it’s proteins.

Question 34

How is the efficiency of the gastric juice's enzymes increased?

Answer 34

it’s necessary for the medium to be acid and this is produced by the hydrochloric acid secreted by oxyntic cell of gastric gland, further action of the HCL acid helps to sterilize the food, thus giving the protection against pathogenic bacteria.

Question 35

How does digestion proceed into the duodenum?

Answer 35

the food meets further conditions in the form of the bile from the liver, the pancreatic juice from pancreas and brush border from the wall of the intestine. Bile is greenish alkaline watery fluid contains no digestive enzymes secreted by hepatocytes The bile containes two salts: 1- bicarbonate, which reduces the acidity of intestinal contents, 2- glycocholate active the pancreatic lipase and lower the surface tension of the fat so that they become emulsified.

Question 36

What is the pancreatic juice?

Answer 36

The pancreatic juice is watery, alkaline fluid very rich in enzymes it contains: * Trypsin act on undigested protein and convert them into amino acid. * Amylase converts polysaccharide starches into maltose. * Lipase splits certain fats into glycerol and fatty acid.