a & p 2.... chapter 25

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cells are chemical factories

that break down organic substrates to obtain energy

cells need

oxygen and nutrients

energy released

inside the cell supports growth, cell division, contraction, secretion, and various other special functions

a lot of energy is released as

...

cells synthesize new compounds to

perform maintenance or repairs, support growth, produce secretions

energy yields of glycolisis, TCA and ETS

Glycolysis..... 2 ATP
TCA cycle......2 ATP
ETS.............28 ATP
NADH from glycolysis...4 ATP
-----------------------------------------------
total 36 ATP

many cells will shift from glucose based to

lipid based ATP production. Cells will shift to proteins for energy only when lipids and carbs are unavailable.

lipids are broken down into

pieces that can be converted into puruvic acid, or channeled into the TCA cycle

which yields more energy...glucose, lipids or protein catabolism?

lipid

one drawback to lipid catabolism

lipids cannot provide large amounts of ATP in a short amount of time.

which lipoprotein is "good" chol

HDL

which lipoprotein is "bad" chol

LDL

amino acids are derived from

proteins taken in a food, tissue proteins that are broken down during normal growth, repair and tissue restructuring

fates of ingested protein

small amounts may be excreted
used to build new proteins
may be oxidized in the Kreb's cycle to produce ATP

*****LISTING QUESTION ****
protein catabolism is an impractical source for quick energy because...

********LISTING QUESTION********
1. proteins are more difficult to break down than complex carbs or lipids
2. one of the byproducts, ammonia, is a toxin that can damage cells
3. proteins form the most important structural and functional components of cells

minerals and vitamins are essential

components of your diet. your body cannot synthesize minerals, and you can generate small quantities of very few vitamins.

mineral functions

act as cofactors in a cariety of enzymatic actions
contribute to osmolarity of body fluids and play a role in transmembrane potentials, action potentials, neurotransmitter release, muscle contraction, construction and maintenance of the skeleton, transport of gases, buffer sustems, fluid absorptions, and waste removal

biochemical reactions produce heat

...

mechanisms to increase heat loss

1. peripheral vasodilation - allows more blood to flow to the skin and the heat will be lost tot he environment through radiation and conduction
2. increased perspiration - cools the body through evaporation of sweat
3. increased respiration - increases evaporative losses through the lungs

mechanisms to promote heat gain

1. decreased blood flow to the dermis - less heat is lost by radiation and conduction to the environment
(a) countercurrent exchange - diffusion
between fluids that are moving in opposite directions Heat diffuses from the warm blood flowing outward to the limbs into the cooler blood returning from the periphery
2. shivering thermogenesis - a form of muscular exercise in which heat is produced as a byproduct of oxidative metabolism
3. nonshivering thermogenesis - hormones speed up oxidative metabolism and hence more heat is produced

thermoregulatory responses differ

between individuals: acclimatization, body weight, age, tissue distribution, surface-to-volume ratios, and hypothalamic thermostats

catabolism

breakdown organic substances to release energy that can be used to make ATP or other high energy compounds (DESTROY-faster)

anabolisn

syntheses of new organic molecules (BUILD)

respiration

the process by which cells produce energy (ATP)

anaerobic respiration

GLYCOLYSIS-porceeds in the abscence of O2. occurs in the cytoplasm

aerobic respiration

TCA OR KREBS CYCLE-occurs only in the presence of O2. occurs in the motochondria

glycolysis

the anaerobic breakdown of glucose to pyruvic acid.
requires glucose molecules, cytoplasmic enzymes, atp and adp, organic phosphates and nad

TCA cycle

function-remove hydrogen atoms, form organic molecules, and transfer them to coenzymes.

ETS

cytochrome system responsible for most of the energy production in living cells. a complex bound to the inner mitochondrial membrane

glucogenesis

the formation of glycogen from fatty acids and proteins instead of carbohydrates

glycogenesis

the conversion of glucose to glycogen when the glucose in the blood exceeds the demand

substrate level phosphorylation

when an enzyme uses the energy released by a chemical reaction to transfer a phosphate group to a suitable acceptor molecule

oxidative phosphorylation

capture of energy as ATP during a series of oxidation-reduction reactions. a sequence that occurs in mitochondria. involves coenzymes and the electron transport system

oxidation

loss of electrons--becoming "+"
*electrons carry chemical energy

reduction

acceptance of electrons--becoming "-"
*electrons carry chemical energy

glycoenolysis

when blood glucose levels dec, this takes place in the liver, and glucose is returned to the blood.

lipogenesis

creation of triglycerides (fat-- fatty acids and glycerol) - move out of bloodstream to store in adipose tissue, (converting excess glucose into lipids)

free fatty acids

water-soluble lipids that can easily diffuse across cell membranes; they are an important energy source during periods of starvation (when glucose supplies are limited)

lipoproteins

-lipid-protein complexes that contain large glycerides and cholesterol with a superficial coating of phospholipids and proteins

nutrition

the absorption of nutrients from food

malnutrition

unhealthy state resulting from inadequate or excessive intake of one or more nutrients

bioenergetics

study of how organisms acquire and use energy

thermoregulation

The homeostatic regulation of body temperature

transamination

enzymatic transfer of an amino group from an amino acid to a keto acid; cells of the liver, skeletal muscles, heart, lung, kidney and brain perform a lot of transaminations

deamination

the removal of an amino group from an amino acid, it generates an ammonia molecule or an ammonium ion (highly toxic).

essential amino acids

(amino acids your body cannot make them) that must be acquired through the diet.

nonessential amino acids

amino acids your body can make

absorptive state

period following a meal, when nutrient absorption is under way. 3 meals a day = 12 hours in absorptive state each day

postabsorptive state

extends from the end of the absorptive state to the next meal; your body relies on internal energy reserves; 12 hours each day

five metabolic components include

liver, adipose tissue, skeletal muscle, neural tissue, and other peripheral tissues

liver... metabolic component

the focal point for the metabolic regulation and control. Liver cells can breakdown or synthesize most carbohydrates, lipids, and amino acids. Contains significant energy reserves (glycogen deposits)

adipose tissue..metabolic component

stores lipids, primarily in the form of triglycerides.

skeletal muscle...metabolic component

contains substantial glycogen reserves, and the contractile proteins can be mobilized and the amino acids used as an energy source

neural tissue...metabolic component

does not contain energy reserves, depends on aerobic metabolism for energy production

peripheral tissue...metabolic component

are able to metabolize glucose, fatty acids, or other substrates under the direction of the endocrine system.

inborn errors of metabolism

inherited inability to produce specific enzymes involved with amino acid metabolism: ex.- phenylketonuria (PKU), albinism, lactose intolerance, Tay-Sach's disease, and hypercholesterolemia

obesity

20% over ideal weight, serious health risks. Obese individuals take in more food energy than they are using

hypervitaminosis

when dietary intake exceeds the ability to store, utilize, or excrete a particular vitamin

anorexia nervosa

individual who is underweight and thinks that they are still too fat, refuse to eat normal amounts of food

bulimia

individual goes on an "eating binge", the meal is then followed by induced vomiting, laxatives (promote movement of material through the digestive tract), diuretics (promote fluid loss in urine

acclimatization

adjusting physiologically to an environment over time

heat cramp

characterized by profuse sweating, cardiovascular and thermoregulator mechanisms are intact

heat exhaustion

there are unreplaced losses of salts and water, sweating, weakness, reduced blood pressure, rapid pulse, normal or slightly elevated temperature

heat stroke

results from a breakdown in thermoregulation. Sweat glands cease to function and body temperature rises. The patient lapses into a coma; the skin is flushed, hot an dry

hypothermia

below-normal body temperature

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