20. Chapter 21- Part 2

Question 1

What are the 3 parts of motility in the digestive system?

Answer 1

1. Slow peristaltic/segmental contractions
2. Haustral rolling or churning- additional muscle layer taenia coli
   When contracted creates pouches called haustra
3. Mass peristalsis- gastrocolic reflex, stimulated by food in stomach

Slide 3 March 11

Question 2

What is the order of relaxation and contraction one two reflexes initiated by distension of rectum are made?

Answer 2

Peristaltic waves
Relaxation of internal sphincter (smooth muscle)
Contraction of external sphincter (skeletal muscle)
Completed by voluntary relaxation of external sphincter
Aided by abdominal contraction

Slide 4 Mar 11

Question 3

What is diarrhea?

Answer 3

Increase in frequency, volume and fluid content of the feces due to increased secretion, reduced absorption or increased motility

Osmotic, secretory, inflammatory, motility induced

Slide 5 March 11

Question 4

What does the use of penicillin alter?

Answer 4

Alters normal bacterial flora and the remaining bacteria have reduced competition for space and nutrients

Leaves you prone to infection by C. Difficile

Question 5

What are M cells?

Answer 5

Play a big role in immune responses: sample lumen contents
Receptor mediated endocytosis

Transport antigens to macrophages, lymphocytes, and dendritic cells

Release cytokines to attract more immune cells to attack invaders

Cytokines can also trigger increased Cl- secretion (diarrhea) to flush out pathogens

Question 6

What is vomiting? (3 responses)

Answer 6

Contents of the stomach and occasionally the small intestine are forcefully expelled through the mouth
Associated with nausea

Vomiting center in medulla causes 3 Responses:

1. Retrograde contractions in the small intestine and stomach
2. Contraction of abdominal and inspiration muscles (diaphragm) increases gastric pressure
3. Relaxation of esophageal sphincters

Slide 8 March 11

Question 7

What is feeding state and fasting state?

Slide 9-11 March 11

Answer 7

Slide 9-11 March 11

Fed state has high amounts of insulin being released from Beta cells

Fasted state has high amount of glucagon released

Slide 3 March 15

Question 8

What is the glucostatic theory and lipostatic theory of long term regulation of feeding behaviour?

Answer 8

1. Glucostatic theory- glucose metabolism in the hypothalamus regulates food intake
2. Lipostatic theory- signals from the bodies fat stores regulate food intake
   Slide 13 March 11

Question 9

What is leptin?

Answer 9

Released from adipocytes and regulates body mass by acting directly on neurons if the hypothalamus that decrease appetite and increase energy expenditure

Question 10

What is response to increased leptin and response to decreased leptin?

Answer 10

Increased leptin:
Acts on arcuate nucleus:
1. Inhibtion of lateral feeding center
2. Activation of PVN (humoral response and visceromotor response)

Decreased leptin:
1. Reduced activation of a-MSH and CART neurons (reduces activation of PVN)
2. Activation of NPY and AgRP containing
Neurons

Slides 14-15 March 11
Slide 4 March 13

Question 11

What is ghrelin?

Answer 11

Released by cells in the stomach in response to emptying
Stimulated NPY/AGRP containing neurons in the arcuate
Ghrelin injection will stimulate food intake experimentally
Slide 6 March 13

Question 12

What is gastric distension?

CCK

Answer 12

Sensed by mechanosensory neurons and this information is sent back to the NTS
CCK is released by I cells in response to fats and amino acids entering the small intestine

Both act on NTS to stimulate the feeling of satiety

Question 13

What does ginger have to do with insulin and blood glucose levels?

Answer 13

During the cephalic and gastric phase increased insulin would cause a drop in blood glucose driving hunger through activation of NOY/AgRP neurons

In intestinal phase the increased blood glucose and corresponding increase in insulin would act as a satiety signal through activation of aMSH/CART neurons in the arcuate nucleus

Question 14

What is energy input and output?

Answer 14

Energy input- diet (hunger/appetite, satiety, social psychological factors)
Energy output- heat (50%) unregulated and thermoregulation
Work (50%)- transport across membranes, mechanical work (movement), chemical work

Question 15

How is energy input and output measured?

Answer 15

Input-bomb calorimeter, heat released from burned food is measured
One kilocalorie is heat needed to raise the temp of 1L of water by 1 degree
Output- energy output=work + heat
Use direct calorimeter

Slides 11-12 March 13

Question 16

What is the basal metabolic rate (BMR)?

6 influencers of it?

Answer 16

Individuals lowest metabolic rate
Measured as resting metabolic rate

1. Age and sex- makes burn more energy
2. Amount of lean muscle mass
3. Activity level- metabolic activity above BMR
4. Diet, diet induced thermogenesis: energetic cost of food digestion and storage differs between different food components
5. Hormones
6. Genetics

Question 17

What is metabolism?

Answer 17

Sum of all chemical reactions in the body

1. Extract energy from nutrients
2. Use energy for work (transport, mechanical, synthesis)
3. store excess energy for later use

Fed state is mainly anabolic

Question 18

What does skeletal muscle, liver and adipocytes do in fed state?

Answer 18

Skeletal muscle- take sup glucose for energy usage and stores glucose as glycogen
Liver- converts glucose to glycogen
Converts glucose to fatty acids
Adipocytes- take up dietary triacylglycerides from chylomicrons
Excess glucose taken up and converted to triacylglycerides
Stores triacylglycerides stored in liver

Question 19

How long can glycogen, proteins, and fats sustain quiet activity?

Answer 19

Glycogen- few hours
Proteins- potentially for long periods of time but decreased protein levels eventually compromise cellular function
Fats- for approximately two months

Question 20

What does skeletal muscle, liver and adipocytes do in fasted state?

Answer 20

Skeletal muscle- converts glycogen to glucose 6P for its own use
Forms pyruvate and lactate
Liver- glycogen converts to glucose and transport throughout body
Produces new glucose from pyruvate, lactate, glycerol and AA’s
Converts FA to ketone bodies for energy usage
Adipocytes- lipolysis occurs, fatty acids and glycerol enter bloodstream to be used as energy in most cells

Question 21

What are the 4 things that increase insulin secretion?

Answer 21

Plasma glucose concentration
Plasma amino acid concentration
Plasma GIP concentration
Parasympathetic activity

Question 22

Study how insulin is released on slide 5 March 15

Study it’s method of action on slide 6 March 15

Answer 22

Ok