Ch. 12 bionergetics and regulation of metabolism (skipped Ch. 11- lipids & amino acid metabolism)

biological systems are considered open or closed when

• open → matter and energy can be exchanged with the environment

• closed → only energy can be exchanged with the environment

changes in ___ in a closed biological system are equal to changes in internal energy, which is equal to heat exchange within the environment

enthalpy

is any work performed in closed biological systems?

no, because pressure and volume remain constant

a measure of energy dispersion in a system

entropy

free energy calculations must be adjusted for

• pH (ΔG°’)

• temperature (37C = 98.6 F = 310K)

• concentrations

ATP contains high-energy ___ bonds that are stabilized upon hydrolysis by resonance, ionization, and loss of charge repulsion

phosphate

ATP provides energy through ___ and ____ to energetically unfavorable reactions

hydrolysis, coupling

ATP can also participate in ____ ____ ____ as a phosphate donor

phosphoryl group transfers

biological oxidation and reduction reactions can be broken down into component

half-reactions

many oxidation-reduction (redox) reactions involve an

electron carrier to transport high-energy electrons

electron ___ may be soluble or membrane-bound

carriers

one subclass of electron carriers that are derived from riboflavin (vitamin B₂)

flavoproteins

_______ is an undesirable state for most biochemical reactions because organism need to harness free energy to survive

equilibrium

in the postprandial/well-fed (absorptive) state, insulin secretion is

high and anabolic metabolism prevails

in the postabsorptive (fasting) state, insulin secretion

decreases while glucagon and catecholamine secretion increases

anabolism

synthesis of biomolecules

catabolism

breakdown of biomolecules for E

the postabsorptive state is observed in _____ fasting, there is a transition to catabolic metabolism

short-term (overnight)

prolonged fasting (starvation) dramatically increases

glucagon and catecholamine secretion

in starvation, most tissues rely on ___ ____ and a max 2/3 of the brains energy can be derived from _____ _____

fatty acids, ketone bodies

______ and ____ nave opposing activities during most aspects of metabolism

insulin, glucagon

insulin causes

a decrease in blood glucose levels by increasing cellular uptake

insulin increases the rate of

anabolic metabolism

insulin secretion by pancreatic Beta cells is regulated by

blood glucose levels

glucagon increases blood glucose levels by

promoting gluconeogenesis and glycogenolysis in the liver

glucagon secretion by pancreatic alpha cells is stimulated by both

low glucose and high amino acid levels

glucocorticoids do what

increase blood glucose in response to stress by mobilizing fat stores and inhibiting glucose uptake

glucocorticoids increase the impact of

glucagon and catecholamines

catecholamines promote glycogenolysis and increase basal metabolic rate through their

sympathetic nervous system activity

____ ____ modulate the impact of other metabolic hormones and have a direct impact on basal metabolic rate

thyroid hormone

T₃ is more potent than T₄ but has a shorter half-life and is available in ___ concentrations in the blood

lower

T₄ is concerted to T₃ at the

tissues

the most metabolically diverse tissue is the

liver

hepatocytes are responsible for the

maintenance of blood glucose levels by glycogenolysis and gluconeogenesis in response to pancreatic hormone stimulation

the liver also participates in the processing of

• lipids

• cholesterol

• bile

• urea

• toxins

adipose tissue stores lipids under the influence of ___ and releases them under the influence of _____

insulin, epinephrine

skeletal muscle metabolism differs based on the

current activity level and fiber type

______ muscle conserves carbohydrates in glycogen stores and uses free fatty acids from the bloodstream

resting

____ muscle may use anaerobic metabolism, oxidative phosphorylation of glucose, direct phosphorylation from creatine phosphate, or fatty acid oxidation depending on fiber type and exercise duration

active

____ muscle uses fatty acid oxidation in both well-fed and fasting states

cardiac

the ____and _____ _____ _____consume glucose in all metabolic states, except for prolonged fasts where 2/3 of the brain’s fuel may come from ketone bodies

brain, other nervous tissues

metabolic rates can be measured using

• calorimetry

• respirometry

• consumption tracking

• measurement of blood concentrations of substrate and hormones

composition of fuel that is actively consumed by the body is estimated by the

respiratory quotient (RQ)

body mass regulation is multifactorial with ____ and ____ as modifiable factors

consumption, activity

the hormones ____, ____, and ____ as well as their receptors play a role in body mass

leptin, ghrelin, orexin

long term changes in body mass result from changes in

lipid storage

changes in consumption or activity must surpass a ___ to cause weight change

threshold

the threshold is ___ for weight gain than for weight loss

lower (aka it is harder to lose than it is to gain weight)

body mass can be measured and tracked using the

body mass index (BMI)