6.1 Nutrition and the Human Digestive System

Question 1

What is Nutrition

Answer 1

Nutrition is the process by which organisms obtain food and energy for growth, repair and
maintenance of the body.

Question 2

In humans, nutrition consists of

Answer 2

• Feeding or Ingestion
• Digestion
• Absorption
• Assimilation

Question 3

The process of Feeding or Ingestion

Answer 3

Food is taken into the body

Question 4

The process of Digestion

Answer 4

• Large food molecules are broken down into smaller, soluble molecules that
  can be absorbed into the body cells.
• Physical digestion: Mechanical break up of food into smaller particles.
• Chemical digestion: Breakdown of large food molecules into smaller soluble
  molecules catalysed by digestive enzymes through hydrolytic reactions.

Question 5

The process of Absorption

Answer 5

Digested food substances are absorbed into the body cells.

Question 6

The process of Assimilation

Answer 6

Some of the absorbed food substances are converted into new protoplasm
or used to provide energy.

Question 7

The mouth contains ?

Answer 7

• Teeth
• Salivary glands
• Tongue

Question 8

What do teeth do?

Answer 8

Chewing action of the teeth breaks down large pieces of food into smaller
pieces. This increases the surface area of the food so enzymes can act on it
more efficiently.

Question 9

what do the Salivary glands do?

Answer 9

• Secretes saliva into the mouth. Saliva flows into the buccal cavity via tubes
  called salivary ducts.

Question 10

what does the tongue do?

Answer 10

• Helps to mix food with saliva. Taste buds on the tongue help to identify and
  select suitable foods.

Question 11

Pharynx

Answer 11

• The pharynx is the part of the gut which connects the buccal cavity to the oesophagus and
  the larynx. The pharynx also leads to the trachea.
• The larynx has a slit-like opening called the glottis.

Question 12

Where and What is the Oesophagus

Answer 12

The oesophagus or gullet is a narrow, muscular tube. It passes through the thorax and the
diaphragm to join the stomach.

Question 13

what is a diaphragm

Answer 13

a sheet of muscle which separates the thorax from the abdomen

Question 14

The wall of the oesophagus contains two layers of muscles, where are these muscles present

Answer 14

These muscles are present along
the whole gut from the oesophagus to the rectum.

Question 15

What are the 2 sets of muscles along the oesophagus?

Answer 15

The two layers of muscles are:
- Longitudinal muscles, on the outer side of the gut wall
- Circular muscles, on the inner side of the gut wall.
- Both sets of muscles produce long, slow contractions that move food along the gut by
peristalsis.

Question 16

What is Peristalsis

Answer 16

Peristalsis is the rhythmic, wave-like muscular contractions in the wall of the alimentary
canal.

Question 17

Peristalsis enables… ?

Answer 17

Peristalsis enables food to be mixed with the digestive juices, and also pushes or propels the
food along the gut.

Question 18

The circular muscles ____ the lumen whereas the longitudinal muscles ____ and
____ the lumen.

Answer 18

The circular muscles constrict the lumen whereas the longitudinal muscles shorten and
widen the lumen.

Question 19

The circular and longitudinal muscles are ____?

Answer 19

The circular and longitudinal muscles are antagonistic muscles.

Question 20

When the circular muscles contract, what hppens

Answer 20

When the circular muscles contract, the longitudinal muscles relax. As a result, the
wall of the gut constricts, and the gut becomes narrower and longer. The food is
squeezed or pushed forwards.

Question 21

When the longitudinal muscles contract, what happens

Answer 21

When the longitudinal muscles contract, the circular muscles relax. The gut dilates,
and it becomes wider and shorter. This widens the lumen for food to enter.

Question 22

What is a stomach

Answer 22

The stomach is a distensible muscular bag, with thick and well-developed muscular walls.

Question 23

When the stomach is fully distended, what does it tell the brain?

Answer 23

it sends signals to the brain that it is full.

Question 24

The stomach wall has numerous pits that lead to _____ that secrete _____ into
the ____ cavity.

Answer 24

The stomach wall has numerous pits that lead to gastric glands that secrete gastric juice into
the stomach cavity.

Question 25

Where is the pyloric sphincter located

Answer 25

The pyloric sphincter is located at the place where the stomach joins the small intestine.

Question 26

What happens when the pyloric sphincter contracts or relaxes?

Answer 26

When the muscle contracts, the entrance to the small intestine closes. When the ring
relaxes, the entrance opens, allowing food to pass from the stomach into the small intestine.

Question 27

Liver ( physical charcateristics and purpose)

Answer 27

• The liver is dark red and is made up of five lobes.
• The liver secretes bile, which is stored in the gall bladder

Question 28

Gall bladder purpose

Answer 28

• Bile is stored temporarily in high concentration in the gall bladder
• Bile flows into the duodenum via the bile duct.

Question 29

Small intestine consists of?

Answer 29

• The small intestine consists of the U-shaped duodenum, the jejunum, and the ileum.

Question 30

The wall of the small intestine is adapted to absorb____?

Answer 30

The wall of the small intestine is adapted to absorb digested food products and water.

Question 31

The lining of the walls of the small intestine contains ____ which secrete ___?

Answer 31

The lining of the walls of the small intestine contains glands which secrete digestive
enzymes.

Question 32

Large intestine consist of?

Answer 32

• It consists of the colon and the rectum.

Question 33

In humans, these have no specific functions, and where are they located

Answer 33

At the junction between the colon and small intestine are the caecum and the appendix.

Question 34

What is The main function of the colon?

Answer 34

absorb water and mineral salts from the undigested
food material. No digestion occurs in the large intestine.

Question 35

Where is Faecal matter temporarily stored

Answer 35

rectum

Question 36

When the rectrum contracts what happens

Answer 36

faeces is
expelled through the anus