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Flashcards in Week 1 Deck (100)
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1

Define digestion

Digestion is the chemical breakdown by enzymatic hydrolysis of complex foodstuffs to smaller, absorbable units.

2

Define absorption

Absorption is the transfer of products of digestion from the digestive tract to the blood or the lymph

3

What are the four layers of the digestive tract wall

Mucosa (inner layer)
Submucosa,
Muscularis Externa,
Serosa (outer layer)

4

What effect does circular muscle and longitudinal muscle contraction have?

Contraction of circular muscle causes the lumen to become narrower and longer
Contraction of longitudinal muscle causes the intestine to become shorter and fatter.

5

How are smooth muscle cells in the GI tract arranged?

The cells are arranged in sheets and coupled by gap junctions

6

Explain the synchronous wave in smooth muscle

- Spontaneous activity is triggered by pacememaker cells (modulated by nerves and hormones)
- This activity causes slow waves which cause hundreds of cells contract at the same time

7

What is meant by slow waves?

Rythmic membrane depolarisation and depolarisation that spreads from cell to cell via gap junctions

8

What is the function of ICCs and where are they located?

These are the pacemaker cells which trigger electrical activity.
They are spread between the smooth muscle cells
(located between the longitudinal and circular muscle layers in the submucosa)

9

In a smooth muscle cell action potential, what is the upstroke and downstroke mediated by?

The upstroke is mediated by voltage-activated calcium channels
The downstroke is mediated by voltage activated potassium channels

10

What 3 stimuli affect whether slow wave amplitude reaches threshold?

Neuronal stimuli
Hormonal stimuli
Mechanical stimuli

11

In terms of basic electrical rhythm, what is the frequency of slow waves in the; stomach, small intestine and large intestine?

Stomach - 3 per min
Duodenum - 12 per min
Ileum - 8 per min
proximal colon - 8 per min
distal colon - 16 per min

12

In the ENS system, what is the purpose of the myenteric plexus and the submucosa plexus

Myenteric plexus - Regulates motility and sphincters
Submucous plexus - Modulates epithelia and blood vessels

13

Which is more important in terms of innervation of the G.I tract; parasympathetic or sympathetic?

PARASYMPATHETIC

14

What effects do parasympathetic have on the G.I tract?

Increase secretions
Increase blood flow
Increase smooth muscle contraction
Relax sphincters and the stomach

15

What effects do sympathetics have on the G.I tract?

Increase sphincter tone
Decrese motility
Decrease secretions
Decrease blood flow

16

Where do parasympathetic and sympathetic fibres synapse?

PARASYMPATHETIC - Ganglion cells
SYMPATHETIC - Prevertebral ganglia

17

What is peristalsis?

A wave of relaxation followed by contraction that proceeds along the gut in aboral direction

18

What do circular and longitudinal muscles do in peristalsis?

Circular muscles contract
Longitudinal muscles relax

19

What is segmentation?

The churning and mixing which is caused by contractions of the circular muscle layer

20

How many sphincters are there in the G.I tract?

6

21

Name the 6 sphincters in the G.I tract

Upper oesophageal
Lower oesophageal
Pyloric
Ileocaecal valve
Internal anal
External anal

22

Which two sphincters have skeletal muscle and are therefore usually under voluntary control?

Upper oesophageal sphincter
External anal sphincter

23

What are the 3 major phases in swallowing?

Oral
Pharyngeal
Oesophageal

24

What diseases can obesity contribute to?

T2DM
Hypertension
Osteoarthritis
NAFLD (fatty liver disease)
Dementia
Stroke
E.T.C

25

What part of the brain is responsible for neural control of factors influencing energy intake and body weight?

HYPOTHALAMUS

26

What is CCK and when is it secreted?

Cholecystokinin
- Secreted in the duodenum and jejunum in proportion to meals

27

What is Ghrelin and when is it produced?

Grehlin is a hunger signal
Its level increase before eating and decrease after eating

28

What are the two hormones which inform the hypothalamus to alter energy balance?

LEPTIN and INSULIN

29

Outline the present drug therapy/management for obesity

ORLISTAT
- Inhibits pancreatic lipase
- Reduces fat absorption in the S.I
BARIATRIC SURGERY
- Gastric by-pass surgery
- Restricts calorie intake
- Substantial weight loss
- Can resolve T2DM

30

Define glycogenesis and glycogenolysis

GLYCOGENESIS - Synthesis of glycogen to from glucose
GLYCOGENOLYSIS -Breakdown of glycogen to form glucose