Digestion

Question 1

What is the function of the gastrointestinal system?

Answer 1

Disassemble ingested materials into absorbable forms, absorb the nutrients then expel the waste

Question 2

What are the 4 mouth processes?

Answer 2

Apprehension
Mastication
Salivation
Deglutition

Question 3

What is apprehension?

Answer 3

Teeth, lips and tongue moving food and retaining it in the mouth

Question 4

What initiates mastication?

Answer 4

Somatic motor

Question 5

Once initiated what happens to mastication?

Answer 5

It becomes automatic

Question 6

How does mastication occur?

Answer 6

Rhythmic alternating in jaw depressor and elevator muscles

Question 7

What is mastication controlled by?

Answer 7

Pattern generator in brainstem

Question 8

What does chewing do?

Answer 8

Grinds food down, stimulates taste buds and increases saliva, gastric, pancreatic and bile secretions

Question 9

What is saliva secreted from?

Answer 9

Parotids, sublingual and submaxillary glands

Question 10

What does saliva contain?

Answer 10

99.5% water and the rest is ions, mucus, alpha-amylase and lysozyme

Question 11

1st step of salivation

Answer 11

Plasma is filtered into the acinus

Question 12

2nd step of salivation

Answer 12

Amylase and HCO3- are added to plasma

Question 13

3rd step of salivation

Answer 13

Ions are reabsorbed from ductile into larger ducts

Question 14

What does saliva break polysaccharide down to?

Answer 14

Maltose

Question 15

How does saliva kill bacteria?

Answer 15

Lysozyme

Question 16

How does saliva neutralise acid?

Answer 16

They include bicarbonate buffers

Question 17

What reflexes cause saliva to be secreted?

Answer 17

Spontaneous, in response to stimulus, unconditional reflex and conditioned reflex

Question 18

What causes spontaneous saliva secretion?

Answer 18

Parasympathetic nerves

Question 19

What produces an unconditioned reflex for saliva secretion?

Answer 19

Chemo and pressure receptors

Question 20

What produces a conditioned reflex for saliva secretion?

Answer 20

Oral stimulation

Question 21

How does deglutition initiate swallowing?

Answer 21

Pushes the food to the back of the mouth

Question 22

How is food moved through the oesophagus?

Answer 22

25 skeletal muscles propel food down where it is pushed through active peristalsis

Question 23

What is the pharynx?

Answer 23

Part of the throat

Question 24

What is the oropharyngeal stage?

Answer 24

Mouth through pharynx into oesophagus

Question 25

How does the stomach help with digestion?

Answer 25

Strongly acidic (pepsin) medium weakens food structure

Question 26

What is chyme?

Answer 26

The acidic slurry that material becomes in the stomach

Question 27

Where is chyme ejected after digestion?

Answer 27

Duodenum

Question 28

What is the inner lining of the stomach called?

Answer 28

Mucosa

Question 29

What are the ridges of the stomach called?

Answer 29

Rugae

Question 30

What are the dotted pits in the stomach?

Answer 30

Gastric glands

Question 31

What is the top and bottom of the stomach called?

Answer 31

Fundus and antrum

Question 32

What material is in the gastric juice?

Answer 32

Water, HCl, pepsinogen, intrinsic factor and mucous

Question 33

Why is intrinsic factor important?

Answer 33

Absorption of B12

Question 34

What cells are in the gastric gland?

Answer 34

Parietal, enteroendocrine, chief and mucous cells

Question 35

Function of parietal cells

Answer 35

Use proton pumps to secrete acid and intrinsic factor into stomach

Question 36

Function of enteroendocrine cells

Answer 36

Secrete hormones into blood

Question 37

Function of chief cells

Answer 37

Secrete pepsinogen

Question 38

What causes gastric secretion to begin?

Answer 38

Arrival of food in stomach activates parasympathetic nerve

Question 39

How do parasympathetic nerves cause gastric secretion?

Answer 39

Activates gastrin and histamine release from G-cells and H-cells

Question 40

How long does it take the stomach to empty after eating?

Answer 40

2-4 hours

Question 41

What causes the stomach to empty?

Answer 41

Signals from small intestine

Question 42

What type of foods are held up for the longest?

Answer 42

Hot, fatty, acidic, hypertonic foods

Question 43

What is located between the oesophagus and stomach?

Answer 43

Rumen, reticulum and omasum

Question 44

Function of the rumen

Answer 44

Provides access to cellulose and hemicellulose

Question 45

Function of rumen in symbiotic microorganisms

Answer 45

Allows removal of waste such as volatile fatty acids and gases

Question 46

Disadvantages of the rumen

Answer 46

Takes up large amount of space for low nutrient content food

Question 47

What is in the top half of the rumen?

Answer 47

'Raft' of fibrous material Surface lined with honeycomb pockets CO2 and CH4 bubble

Question 48

What are the honeycomb pockets lined with?

Answer 48

Plicae

Question 49

What is in the lower half of the rumen?

Answer 49

Liquid containing digested material, microorganisms and saliva

Question 50

What is rumination?

Answer 50

Allows material to be chewed again to increase surface area and bacteria work

Question 51

Where does digested material go after the rumen?

Answer 51

Omasum

Question 52

Function of motor action in the rumen

Answer 52

Removes gas products of fermentation and initiates rumination

Question 53

What are the 2 cycles involved in mixing contents in the rumen?

Answer 53

A and B cycle

Question 54

1st step of A cycle

Answer 54

Double contraction of reticulum ejects material into omasum

Question 55

2nd step of A cycle

Answer 55

Fibrous 'raft' dislodges causing particles to sink

Question 56

3rd step of A cycle

Answer 56

Final contraction propels digested material into reticulum

Question 57

What is the B cycle?

Answer 57

Fermentation produces gas therefore gas bubbles move over cardia which allows them to escape