Hunger and Eating (ch.12) Flashcards
1
Q
Homeostasis
A
- Maintains internal states within a critical range
- Because things like warmth water and food are VITAL and SCARCE
- > We have elaborate systems to monitor and maintain them
- Primarily employs negative feedback mechanisms (deviation from a set point triggers a compensatory (recompense someone who has experienced loss) response.
- Generally a set zone and not a set point
- Otherwise no tolerance in the system leading to constant fluctuations between on and off
2
Q
2 hallmarks of these systems:
A
- Redundancy think “failsafe” backup system
2. Rely on Behaviour to acquire more water and food etc
3
Q
Food and energy regulation
A
- Requires an anticipation for future needs
4
Q
What us food necessary for:
A
- Energy
- Critical nutrients (essential amino acids/ vitamins/ minerals)
5
Q
Because food availability is unpredictable…
A
We must have a reserve at all times
6
Q
Why is it difficult to lose weight?
A
- As intake decreases so does basal metabolism (# of calories your body would burn if you stayed in bed all day) - in effort to maintain body weight
7
Q
Calories Restriction:
A
Only known way to increase longevity in animals
- Reduction of daily caloric intake by 50-75 % increases lifespan
- > May be related to a decrease in the basal metabolism
- > may involve SIRT a ubiquitous protein that can control the production of trophic factors ( promote cell growth and survival
8
Q
JAPANESE STUDY IN TEXTBOOK
A
gfs
9
Q
Immediate Energy Sources
A
- Immediate source of energy for the body: complex carbs
- Complex carbs are broken into sugars
- Primary sugar used by body: glucose
10
Q
Short Term Energy Sources
A
- We need steady supply of energy between meals - body has mechanisms for storing it
- GLUCOSE is converted to GLYCOGEN in a process called glycogenesis
- > promoted by Insulin
- > Glycogen is primarily stored in the liver and muscles
- When blood glucose decreases (between meals) Glycogen is removed from storage back into glucose
11
Q
Longer Term Energy Sources:
A
- Take place in the form of fat
- fat is deposited into fat storing cells that form adipose tissue
-> some fats are stored directly from diet (fatty acids)
Others are from excess sugars - during SHORT TERM food storage (process = gluconeogensis)
- during LONGER TERM food storage (process= ketogenesis) -> brain can also use ketones for energy in this case
12
Q
What is the basis for ketogenic diets?
A
High protein; low carb
13
Q
What is crucial for regulation of body metabolism?
A
Insulin
- 2 key points:
1. Insulin is crucial for conversion of glucose to glycogen
2. Insulin is crucial for enabling the body to use glucose - Glucose transporters span cell membranes and move glucose into cells
- Peripheral cell glucose transporters only function in the presence of insulin
- Glucose transporters in the brain do not require insulin
14
Q
3 Factors that stimulate Insulin Release:
A
- Sensory stimulation from food elicit conditioned release of insulin - Cephalic Phase
- During digestion - food entering the stomach/intestine - gut hormones - insulin release
- Absorptive Phase - glucodetectors: cells in the liver detect glucose entering circulation and signal for pancreas to release insulin
15
Q
Lack of Insulin - Diabetes Mellitus (Type 1)
A
- Pancreas stops making insulin
- Brain can still use clucose as insulin not needed to uptake by cells HOWEVER body cannot use glucose in the absence of insulin
- Body starts using fatty acids for energy
- Lack of insulin also prevents glucose from being stored as glycogen THEFORE it is excreted in urine
- Diabetes Mellitus literally means
“passing honey”
