20. Chapter 21- Part 2 Flashcards
What are the 3 parts of motility in the digestive system?
- Slow peristaltic/segmental contractions
- Haustral rolling or churning- additional muscle layer taenia coli
When contracted creates pouches called haustra - Mass peristalsis- gastrocolic reflex, stimulated by food in stomach
Slide 3 March 11
What is the order of relaxation and contraction one two reflexes initiated by distension of rectum are made?
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
What is diarrhea?
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
What does the use of penicillin alter?
Alters normal bacterial flora and the remaining bacteria have reduced competition for space and nutrients
Leaves you prone to infection by C. Difficile
What are M cells?
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
What is vomiting? (3 responses)
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:
- Retrograde contractions in the small intestine and stomach
- Contraction of abdominal and inspiration muscles (diaphragm) increases gastric pressure
- Relaxation of esophageal sphincters
Slide 8 March 11
What is feeding state and fasting state?
Slide 9-11 March 11
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
What is the glucostatic theory and lipostatic theory of long term regulation of feeding behaviour?
- Glucostatic theory- glucose metabolism in the hypothalamus regulates food intake
- Lipostatic theory- signals from the bodies fat stores regulate food intake
Slide 13 March 11
What is leptin?
Released from adipocytes and regulates body mass by acting directly on neurons if the hypothalamus that decrease appetite and increase energy expenditure
What is response to increased leptin and response to decreased leptin?
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
What is ghrelin?
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
What is gastric distension?
CCK
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
What does ginger have to do with insulin and blood glucose levels?
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
What is energy input and output?
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
How is energy input and output measured?
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
What is the basal metabolic rate (BMR)?
6 influencers of it?
Individuals lowest metabolic rate
Measured as resting metabolic rate
- Age and sex- makes burn more energy
- Amount of lean muscle mass
- Activity level- metabolic activity above BMR
- Diet, diet induced thermogenesis: energetic cost of food digestion and storage differs between different food components
- Hormones
- Genetics
What is metabolism?
Sum of all chemical reactions in the body
- Extract energy from nutrients
- Use energy for work (transport, mechanical, synthesis)
- store excess energy for later use
Fed state is mainly anabolic
What does skeletal muscle, liver and adipocytes do in fed state?
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
How long can glycogen, proteins, and fats sustain quiet activity?
Glycogen- few hours
Proteins- potentially for long periods of time but decreased protein levels eventually compromise cellular function
Fats- for approximately two months
What does skeletal muscle, liver and adipocytes do in fasted state?
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
What are the 4 things that increase insulin secretion?
Plasma glucose concentration
Plasma amino acid concentration
Plasma GIP concentration
Parasympathetic activity
Study how insulin is released on slide 5 March 15
Study it’s method of action on slide 6 March 15
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