The Digestive System

Question 1

What is the largest endocrine organ in the body?

Answer 1

The digestive system, although there are cells scattered throughout the GIT

Question 2

Ingested food is obviously an energy

Answer 2

source

Question 3

Ingested food is digested and absorbed, what happens to the simple molecules obtained

Answer 3

they travel into cells via the circulatory system

Question 4

*Label the following organs of the gastrointestinal tract

Answer 4

there ya go

Question 5

What are the four digestive processes

Answer 5

motility, secretion, digestion and absorption

Question 6

Of the four digestive processes, we have motility, what type of muscle makes up the motility parts?

Answer 6

Smooth muscle

Question 7

Smooth muscle makes up the motility process of digestion, why is this?

Answer 7

Because it is involuntary

Question 8

Although the smooth muscle in the walls of the digestive tract is phasic smooth muscle, it also maintains a constant low level of contraction, what is this called?

Answer 8

It is called tone

Question 9

What is phasic digestive motility?

Answer 9

Phasic smooth muscle that displays action potential induced bursts of contraction

Question 10

What are the two types of movement that come under phasic digestive motility?

Answer 10

Propulsive movements and mixing movements

Question 11

One of the four processes making up digestion is phasic digestive motility, describe propulsive movements

Answer 11

Propelling or pushing the contents forward through the digestive tract with the rate of propulsion varying depending on the function accomplished by the different regions

Question 12

Where would the rate of phasic digestive motility, propulsive movements be quickest and why?

Answer 12

In the oesophagus because the structure merely serves as a passageway from the mouth to the stomach

Question 13

Where would the rate of phasic digestive motility, propulsive motion be slowest and why?

Answer 13

In the small intestines because it allows time for the breakdown and absorption of food

Question 14

Mixing, a type of phasic digestive motility serves a twofold function, what is this?

Answer 14

Firstly, it mixes food with digetive juices, these movements promote digestion of the food. Secondly, they facilitate absorption by exposing all parts of the intesitnal contents to the absorbing surfaces of the digestive tract

Question 15

Mixing occurs in both the small and large intestine, where would it occur at a slower rate?

Answer 15

In the large intestine

Question 16

One of the four digestive processes involves secretion, what two types of secretion may occur

Answer 16

endocrine and exocrine

Question 17

Where does endocrine secretion take place

Answer 17

cells are scattered throughout the GIT - gi hormones and gi peptides

Question 18

where does exocrine secretion take place

Answer 18

cells in the lining of the git and accessory digestive organs

Question 19

what is the difference between endocrine and exocrine gland secretions?

Answer 19

Generally speaking, exocrine glands are duct glands i.e;these glands are provided with ducts to transport their secretions.Eg:-salivary glands,pancres etc; Whereas Endocrine glands are ductless glands i.e;they release their secretions directly into blood stream.

Question 20

what is one of the four processes of digestion, digestion itself?

Answer 20

Digestion is the chemical breakdown of food stuffs, by enzymatic hydrolysis

Question 21

what is enzymatic hydrolysis?

Answer 21

Enzymatic hydrolysis is a process in which enzymes facilitate the cleavage of bonds in molecules with the addition of the elements of water.

Question 22

what is one of the four processes involved in digestion, absorption about?

Answer 22

small units being transferred from the GIT lumen to the blood or the lymph

Question 23

The gastrointestinal tract is made of four layers, name these four layers

Answer 23

1. Mucosa
2. Submucosa
3. Muscularis externa
4. Serosa

Question 24

What does the mucosa line?

Answer 24

The luminal surface

Question 25

What is the function of the mucosa?

Answer 25

It has a protective function

Question 26

There are regional differences in the mucosa in various parts of the GI tract, what are these and why?

Answer 26

Some areas of the GI tract have mucosa which has greater folding because they require a larger surface area

Question 27

What is the submucosa?

Answer 27

A layer of connective tissues

Question 28

Name two vessels present in the submucosa connective tissue

Answer 28

Blood and lymph vessels

Question 29

What nerve plexus is found in the submucosa and what is it called?

Answer 29

The submucosal plexus

Question 30

What is the muscularis externa made of?

Answer 30

A smooth muscle layer

Question 31

The smooth muscle layer making up the muscularis externa is made of two muscle layers, what are these?

Answer 31

The inner circular layer and the outer longitudinal layer

Question 32

What is the function of the inner circular layer

Answer 32

to contract to decrease diameter

Question 33

what is the function of the outer longitudinal layer

Answer 33

to contract to decrease length

Question 34

What movements do the muscles in the muscularis externa aid in

Answer 34

propulsive and mixing movements

Question 35

There is a nerve plexus found in the muscularis externa which is the third layer of the GI tract, what is it called?

Answer 35

The myenteric plexus

Question 36

what is a nerve plexus?

Answer 36

A nerve plexus is a plexus (branching network) of intersecting nerves. A nerve plexus is composed of afferent and efferent fibers that arise from the merging of the anterior rami of spinal nerves and blood vessels.

Question 37

what is the serosa?

Answer 37

a connective tissue layer

Question 38

what does the serosa layer of the GI tract secrete?

Answer 38

serous fluid

Question 39

what is the serosa, being one of the layers of the GI tract continous with?

Answer 39

The mesentary

Question 40

what is the mesentary?

Answer 40

a fold of the peritoneum which attaches the stomach, small intestine, pancreas, spleen, and other organs to the posterior wall of the abdomen.

Question 41

the regulation of digestive function involves four factors, what four factors are these?

Answer 41

1. autonomous smooth muscle function 2. intrinsic nerve plexuses 3. extrinsic nerves 4. gi hormones

Question 42

GIT smooth muscle undergoes rhythmic depolarisations/repolarisations under autonomous smooth muscle function, what self induced cells allow this to happen?

Answer 42

The interstitial cells of Cajal

Question 43

What are the interstitial cells of Cajal and what do they resemble?

Answer 43

They are pacemaker cells, like self excitable cardiac muscle cells

Question 44

What is the function of the interstitial cells of Cajal

Answer 44

They are pacemaker cells that display rhymthmic spontaneous variations in the membrane potential

Question 45

What is the prominent type of self induced electrical activity in the digestive smooth muscle?

Answer 45

Slow-wave potentials, also referred to as the diestive tract's basic electrical rhythm, BER

Question 46

The electrical activity under autonomous smooth muscle control spreads from cells by what?

Answer 46

gap junctions

Question 47

The sheets of muscles which are under basic electrical rhythm act as one unit, what is this called?

Answer 47

functional synctium

Question 48

BER produces slow waves and not action potentials but if the threshold potential is reached what happens?

Answer 48

Action potentials are triggered resulting in muscle contraction

Question 49

Various factors determine whether a threshold is reached in BER, list three

Answer 49

Mechanical - distension of GIT - so like a bolus of food Nervous Hormonal

Question 50

The frequency of slow waves is detemined by the inherent rate by what?

Answer 50

pacemaker cells establish an inherent rate

Question 51

The frequency of slow waves varies along the

Answer 51

GI tract

Question 52

The intensity of contraction by BER once the threshold potential is reached can vary, this is determined by which two factors?

Answer 52

The number of action potentials and the cytosolic Ca2+ concentration

Question 53

The enteric nervous system acts on a local scale, what is this therefore referred to as?

Answer 53

Intrinsic regulation

Question 54

What nerve is part of the enteric nervous system and runs along the entire length of the GI tract?

Answer 54

Intrinsic nerve plexus

Question 55

The enteric system is a sub division of what nervous system?

Answer 55

the peripheral nervous system

Question 56

The ENS nerves are embedded in the walls of what?

Answer 56

The GI tract

Question 57

On what scale does the enteric nervous system act?

Answer 57

On a local scale- coordinates local activity

Question 58

what are the two types of ganglia making up the enteric nervous system

Answer 58

the myenteric plexus and the submucosal plexus

Question 59

what is the function of the myenteric plexus

Answer 59

responsible for motility

Question 60

what is the function of the submucosal plexus

Answer 60

controls secretory activity and blood flow

Question 61

On what scale does the autonomic nervous system act and what is this therefore referred to as?

Answer 61

Not on a local scale lol and it is therefore extrinsic

Question 62

What is the autonomic nervous system a part of?

Answer 62

The cns

Question 63

What are the two divisions that innervate the smooth muscle of the GI tract?

Answer 63

parasympathetic and sympathetic - opposing actions mostly

Question 64

List two neurotransmitters that influence the regulation of digestive function through the autonomic nervous system

Answer 64

acetylcholine and noradrenaline

Question 65

Is acetylcholine involved in the parasympathetic or sympatheic nervous system?

Answer 65

parasympathetic

Question 66

What does acetylcholine do in the parasympathetic system of the autonomous regulation of the digestive tract

Answer 66

It increases motility and increases secretion

Question 67

is noradrenaline involved in the parasympathetic or sympathetic nervous system?

Answer 67

sympathetic

Question 68

what does noradrenaline do in the sympathetic system for the regulation of digestive function?

Answer 68

It decreases motility and decreases secretion

Question 69

GI hormones have an affect on the regulation of the digestive function, what two things can they do

Answer 69

they may have an inhibitory or excitatory effect on the GIT smooth muscle and exocrine gland cells

Question 70

what is the first step in the digestive process?

Answer 70

mastication

Question 71

What are the three functions of mastication?

Answer 71

1. break down food into smaller pieces 2. mix food with saliva 3. stimulate taste buds

Question 72

one of the functions of mastication is to break down food into smaller pieces for what?

Answer 72

to facilitate in swallowing and to increase the surface area for salivary enzymes

Question 73

How many major pairs of salivary glands are there?

Answer 73

three homie

Question 74

What are the three major pairs of salivary glands?

Answer 74

sublingual, submandibular and parotid

Question 75

what is saliva made of?

Answer 75

h20, electrolytes and protein

Question 76

WHat are three important salivary proteins?

Answer 76

amylase, mucus and lysosyme

Question 77

*Label the three salivary glands

Answer 77

There ya go

Question 78

How does the saliva aid in the breakdown of food?

Answer 78

Due to the presence of dietary starches such as amylase

Question 79

How does the saliva facilitate in swallowing

Answer 79

because it has mucus

Question 80

Saliva has an antibactrial action, due to what?

Answer 80

lysosyme

Question 81

Saliva has bicarbonate buffers, what is this for?

Answer 81

to neutralise pH

Question 82

Salivary secretion is continous, roughly what is the average secretion per day

Answer 82

1/2 litres

Question 83

What is the basal salivary secretion?

Answer 83

it is low level parasympathetic activity which is continous and occurs in the absence of any stimulus

Question 84

Salivary secretion can be reflexly increased from the basal salivary secretion in which two ways

Answer 84

simple reflex and conditioned reflex - by the autonomic nervous system

Question 85

what causes the simple reflex for salivary secretion to be activated

Answer 85

chemoreceptors and pressure receptors are activated

Question 86

explain how the simple reflex involved in salivary secretion works

Answer 86

stimulus - impulses - salivary centre - implulses (extrinsic autonomic nerves) - salivary glands - secretion

Question 87

What is a conditioned reflex

Answer 87

a learned response

Question 88

How does a conditioned reflex of the salivary secretion come about

Answer 88

salivation occurs without oral stimulation, from thinking/seeing/smelling food

Question 89

what mediates the conditioned reflex of salivary secretion?

Answer 89

mediated via cerebral cortex

Question 90

what is special about salivary secretion, the simple and conditioned reflex

Answer 90

they are both ONLY under neural control