L17-metabolism Flashcards
Metabolism
All Chemical & energy transactions in organisms
Energy input is from
Food energy
Energy output is caused from
Internal work - breathing, digestion, nerve conduction
External work - eyes movement, posture
What are the three states of energy balance
- Energy output = energy output
- Energy input > energy output = gain weight
- Energy input < energy output = lose weight
Energy balance equation
E in= E out
(Food intake) (metabolic rate)
Adaptive thermogenesis
Heat energy expended in response to
1. Ambient temperature ( shivering/ sweating)
2. Digestion/ absorption of food
Basal metabolic rate
Rate of burning fuel in cells when awake, resting, fasting, and at comfortable temperature (“coat of living”)
What is regulated by the body?
- Food intake (hormones)
- Adaptive thermogenesis (by shivering/sweating)
- Basal metabolic rate ( by thyroid hormone)
Regulation of food intake to maintain energy balance equation
Food intake = BMR + activity + adaptive thermogenesis
Hunger regulation is maintained by what 3 hormones
Leptin, insulin and ghrelin
Leptin (adipocytes) and insulin (pancreas) stimulates
“satiety” ( satisfy) center in hypothalamus
- long term regulation of body fat
Ghrelin
Released by empty stomach
- stimulates “hunger” center in hypothalamus
- short term/immediate regulation
Where are the two places fat or adipocytes can be found
- Subcutaneous fat
- Visceral fat
Subcutaneous fat
Located under skin/ subcutaneous
Visceral fat
Located around internal organs
Is subcutaneous or visceral fat more sensitive to insulin
Subcutaneous fat = lowers risk of diabetes
Visceral fat = higher risk to diabetes
Not all fat is created equal
TRUE or False
True
Regulation of body temperature NFL
Sensors, integrator, effectors
Sensor: thermoreceptors in hypothalamus & skin
Integrator: hypothalamus via sympathetic NS
Effectors:
Heat - vasodilation, sweating
Cold - vasoconstriction , shivering, piloerectiom
Relationship between ambient temperature, body temperature, and metabolic rate
- body temperature must remain constant
- body will compensate to a point for heat loss/ heat gain
- metabolic rate will increase as body compensates to maintain body temperature
Ambient temperature (T) demonstrates
Stable body temp to appoint until it’s too high or too low
Metabolic rate (mb) demonstrates
- BMR is maintained w/in a narrow range of ambient temperatures
Outside narrow range = body compensate for heat gain/ loss
Thermoneutral zone (TNZ)
Narrow range metabolic rate is maintained
- 79-91 F
How is the TNZ maintained
Body temperature is maintained by dilation/constriction of vessels
MR = BMR
If Temperature is outside the TNZ such as too high and too low what needs to be done
Lose heat = sweat
Gain heat = shiver
( this causes metabolic rate to increase)
How is basal metabolic rate (BMR) measured
- amount of heat generated
- amount of oxygen consumed
How is basal metabolic rate regulated?
Thyroxine (T4) - converted to active T3 inside target cell
Mechanism of basal metabolic rate
Increase rate of cell respiration = increases BMR
- metabolic rate = BMR + physical activity + adaptive thermogenesis
What are the 2 fuel sources (pool of energy substrates)
Reserves & circulating
Reserves
Used between meals when we are fasted
- glycogen - glucose
- fat stores - fatty acids
- protein = amino acids
Circulating
Use after meals when we are feasted
- glucose
- fatty acids
- amino acids
Fuel metabolism
All reactions involving degradation, synthesis and transformation of fats, proteins, and carbohydrates
Ambolism
Synthesis: building up
Catabolism
Degradation: breaking down
Fuel metabolism rules
- Cell respiration is ongoing (independent of eating)
- Cell respiration can burn all monomers ➡️ ATP
- Ingestion provides excess nutrients that must be dealt with
- Brain normally uses only glucose
- Glucose can be made form:
- amino acids ( during starvation/ fasting)
- glycerol
-
Goal of fuel metabolism
Provide cells with what they need
Problem with fuel metabolism
We switch from feasted to fasted states
And brain always needs glucose
How does the body ensure glucose for the brain at all times?
Hormones!!
- store fuel after feasting
- release fuel during fasting
What organs are involved in fuel metabolism
Intestines, liver, adipose tissue & muscle
Intestines function in fuel metabolism
Supplies fuel after a meal
Livers function in fuel metabolism
Stores fuel and inter conversion of free fatty acids to ketones during starvation ➡️ for brain
Muscles function in fuel metabolism
Stores fuel
Adipose tissue function in fuel metabolism
Stores fuel
Gluconeogenesis (as’s, glycerol)
Make new glucose from amino acids and glycerol ( triglycerides)
Glycogenolysis
Break down glucose it already has
Glycogenesis
After a meal store glucose
Ketogenesis
Turn free fatty acids into ketones for the brain to use as fuel
Short term regulation of blood glucose
(Meal to meal)
Insulin - decrease blood sugar
Glucagon- increase blood sugar
Long term regulation of blood glucose
( response to stress, cold exposure, growth spurts)
Regulated by hormones
- epinephrine = increase blood sugar
- cortisol = increase blood sugar
- growth hormone = increase blood sugar
Insulin
Lowers blood sugar, promotes nutrient storage (anabolism)
How does insulin lower blood sugar levels?
Inserts glucose channels into cell
Lipogenesis
Formation of new triglycerides (fat) in adipose tissue
Lipoysis
Breakdown of triglycerides in adipose tissue
Insulin effects on the liver, muscles and adipose tissue
Liver = stores glucose ( glycogenesis)
Muscles = store glycogen/ build protein ( glycogenesis , protein synthesis)
Adipose tissue = creates fat ( lipogenesis)
Glycogen
Raises blood sugar levels, promotes energy release (catabolism)
How does glycogen raise blood sugar levels?
Phosphorylates enzymes by cAMP (2nd messengers)
Glucagons effects on the liver and adipose tissue
Liver = breaks down glycogen to glucose (glycogenolysis, gluconeogensis)
Adipose tissue = breaks down fat (lipolysis)
Stress
Physical, mental, or emotional factor that causes bodily or mental tension
Stress response
A generalized nonspecific response to any major threat to homeostasis
Stressors
Anything that causes stress
- physical trauma
- emotional trauma
- strenuous exercise
- cold
Adrenal gland ________ stress response
Mediates
Cortisol
- releases by adrenal cortex
- responds to long term stress ( sickness)
Epinephrine
- released by adrenal medulla
- it responds to fast stress (short term) - fight or flight
Lambic system
Emotions
What stress requires a physical response “fight or flight”
- acute stress
- activated adrenal medulla via Sympathetic NS
What stress doesn’t require a physical response
- cold stress, growth, emotional stress, trauma, sickness
- activated adrenal cortex ( cortical)
- causes immune suppression overtime = illness
