L17-metabolism Flashcards by Hailey Lopez

Metabolism

All Chemical & energy transactions in organisms

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Energy input is from

Food energy

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Energy output is caused from

Internal work - breathing, digestion, nerve conduction

External work - eyes movement, posture

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What are the three states of energy balance

Energy output = energy output
Energy input > energy output = gain weight
Energy input < energy output = lose weight

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Energy balance equation

E in= E out

(Food intake) (metabolic rate)

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Adaptive thermogenesis

Heat energy expended in response to
1. Ambient temperature ( shivering/ sweating)
2. Digestion/ absorption of food

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Basal metabolic rate

Rate of burning fuel in cells when awake, resting, fasting, and at comfortable temperature (“coat of living”)

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What is regulated by the body?

Food intake (hormones)
Adaptive thermogenesis (by shivering/sweating)
Basal metabolic rate ( by thyroid hormone)

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Regulation of food intake to maintain energy balance equation

Food intake = BMR + activity + adaptive thermogenesis

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Hunger regulation is maintained by what 3 hormones

Leptin, insulin and ghrelin

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Leptin (adipocytes) and insulin (pancreas) stimulates

“satiety” ( satisfy) center in hypothalamus
- long term regulation of body fat

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Ghrelin

Released by empty stomach
- stimulates “hunger” center in hypothalamus
- short term/immediate regulation

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Where are the two places fat or adipocytes can be found

Subcutaneous fat
Visceral fat

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Subcutaneous fat

Located under skin/ subcutaneous

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Visceral fat

Located around internal organs

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Is subcutaneous or visceral fat more sensitive to insulin

Subcutaneous fat = lowers risk of diabetes

Visceral fat = higher risk to diabetes

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Not all fat is created equal

TRUE or False

True

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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

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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

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Ambient temperature (T) demonstrates

Stable body temp to appoint until it’s too high or too low

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Metabolic rate (mb) demonstrates

BMR is maintained w/in a narrow range of ambient temperatures
Outside narrow range = body compensate for heat gain/ loss

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Thermoneutral zone (TNZ)

Narrow range metabolic rate is maintained

79-91 F

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How is the TNZ maintained

Body temperature is maintained by dilation/constriction of vessels

MR = BMR

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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)

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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

1. Cell respiration is ongoing (independent of eating) 2. Cell respiration can burn all monomers ➡️ ATP 3. Ingestion provides excess nutrients that must be dealt with 4. Brain normally uses only glucose 5. 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