KNES 323 Midterm Review

Homeostasis

is a condition of equilibrium, or balance, in the body's internal environment

How is homeostasis maintained?

regulatory processes

to maintain homeostasis, control system must be able to:

detect deviations from normal.

integrate the information with other relevant information

make. appropriate adjustments to restore a factor to its desired value.

circadian rhythm

endogenous autonomous oscillators that result in a ~24 hour day/night cycles

two homeostasis control systems:

intrinsic and extrinsic

intrinsic homeostasis control system

local controls that are inherent in an organ

extrinsic homeostasis control system

regulatory mechanisms initiated outside an organ. accomplished by nervous and endocrine systems.

- hormones

-epinephrine and adrenaline

- nerves

- sympathetic

- increase heart rate

- vagus

- decrease heart rate

control of homeostasis

to make dynamic equilibrium adjustments

feedback loops

responses made after a change

- negative and positive

feedforward loops

responses made in anticipation of a change

steps to control homeostasis

1. stimulus

2. controlled condition

3. response

4. homeostasis

macromolecules

large molecules necessary for life built from smaller organic molecules

4 main macromolecules

carbohydrates, lipids, proteins, nucleic acids

how are lipids broken down?

lipolysis

polymers are broken down via

hydrolysis

carbohydrates

simplest of macromolecules

types of saccharides

monosaccharides, disaccharides, polysaccharides

Monosaccharides

simplest sugars and cannot be broken down by hydrolysis, can readily be used as fuel sources in the body

3 monosaccharides

glucose, fructose, galactose

glucose

source of energy during cellular respiration, used to make ATP

fructose

naturally occurring sugar found in fruits used to aid in glycolysis and helps replenish liver glycogen stores

ribose and deoxyribose

pentose sugars found in nucleic acids. deoxyribose is found in DNA, ribose in RNA

Disaccharide

two monosaccharides bonded together, one always being glucose

3 main disaccarides

sucrose, lactose, maltose

sucrose

most common dietary disaccharide, makes up 25% of calories consumed, in most foods that contain carbohydrates

lactose

only natural source is from milk

maltose

made from two glucose molecules, found in beer, contributes small amount to the dietary carbohydrate

Polysaccharides

a long chain of monosaccharides; may be branched or unbranched

main types of polysaccharides

starch, glycogen, cellulose, chitin

starch

storage form of carbohydrates in plants

Amylose (starch)

long, straight chains the are twisted to form helical coils (slow to breakdown)

Amylopectin

highly branched glucose chains (fast to breakdown)

glycogen

storage form of carbohydrates within animals (muscle and liver), highly branched, converted to glucose in the body via glycogenolysis

cellulose

most abundant naturally occurring polysaccharide, long straight chains, very hard to breakdown

chitin

found in exoskeleton of anthropods, similar to cellulose (long straight chain), made into flexible surgical thread that decomposes

proteins

perform essential functions, long chains of amino acids

proteins are important for:

catalyzing chemical reactions

synthesizing and repairing DNA

transporting materials across the cell

receiving and sending chemical signals

responding to stimuli

providing structural support

what are proteins made of?

20 different amino acids required by the body that make up the proteins

50 000 different proteins in the body

function of each protein will depend on how each protein is shaped

primary protein structure

chain of amino acids

secondary protein structure

folding of the polypeptide chain into helices or sheets

tertiary protein structure

3D folding pattern of a protein due to side chain interactions

quaternary protein structure

protein consisting of more than one amino acid chain

enzymes

proteins that catalyze biochemical reactions

- essential for chemical processes like digestion and cellular metabolism

- without; processes would go so slow, life would not exist

anabolic enzymes

enzymes that build more complex molecules from their substrates

catabolic enzymes

enzymes that break down their substrates

enzymes for digestion

amylase, pepsin, lipase, trypsin

amylase

digestion carbohydrates in mouth and small intestine

pepsin

digestion of proteins in the stomach

lipase

emulsify fats in then small intestine

trypsin

further digestion of proteins in the small intestine

hormones

proteins secreted by the endocrine cells and act to control or regulate specific physiological processes

hormone uses

growth

development

metabolism

reproduction

insulin

A protein hormone synthesized in the pancreas that regulates blood sugar levels by facilitating the uptake of glucose into tissues

hormones(not proteins)

estrogen and testosterone (lipid steroids)

lipids

fats, oils, waxes and other similar compounds in our bodies

What are lipids made of?

carbon, hydrogen, oxygen

non-polar (do not dissolve in water)

transported in blood via lipoproteins

lipids uses

cell membranes, insulation, storage of energy

fats

single glycerol molecule and three fatty acids

saturated fatty acids

have the maximum number of hydrogen atoms possible and no double bonds

- solid at room temp

unsaturated fatty acids

have one or more double bonds

- liquid at room temp

- can be mono or poly

phospholipids

major components of the plasma membrane

- have 2 fatty acids and a phosphate group that help form diacylglycerol

-head is hydrophilic

- tail is hydrophobic

phosopholipid bilayer

only lipophilic solutes can easily pass the bilayer

- cell communication and metabolism

steroids

play roles in reproduction, absorption, metabolism regulation, and brain activity

- have a fused ring structure

- four linked carbon

- hydrophobic and insoluble in water

cholesterol

most common steroid

- plays a role in synthesizing aldosterone

- contributes to formation of cortisol

cholesterol is a precursor to:

Vitamin D, steroid hormones

nucleic acids

DNA (deoxyribonucleaic acid) and RNA (ribonucleic acid)

DNA

genetic material found in all living organisms

RNA

involved in protein synthesis

energy balance

every intake= internal heat produced + external work+ internal work+ energy storage

law of thermodynamics

energy cannot be created or destroyed, only transformed

energy input

Energy in ingested food

- high energy bonds of ATP

energy output

external work

energy from nutrients that is not used to perform work

internal work

3 states of energy balance

neutral, positive, negative

neutral energy balance

Energy input = energy output

Body weight remains constant

positive energy balance

energy intake is greater than energy expended, generally resulting in weight gain

negative energy balance

energy intake is less than energy expended, resulting in weight loss

metabolic rate

total amount of energy we need to expend (both internal and external) in order to perform a given task

metabolic rate=energy expenditure/unit of time

basal metabolic rate (BMR)

minimal internal energy expenditure we need to maintain in order to get the basic physiological functions in our body

to determine BMR a calorimetry assessment under which conditions:

person at physical rest

person at mental rest

done at comfortable room temp

no food within 12 hours

factors influencing metabolic rate

thyroid hormone levels

sympathetic stimulation (epinephrine/norepinephrine)

exercise

daily activities

sex/gender

age

metabolism

set of life- sustaining chemical processes that enables organisms transform the chemical energy stored in molecules into energy that can be used for cellular processes

- breaks down carbohydrates, lipids, proteins, nucleic acids we consume to prove chemical energy for ou cellular processes

exothermic reactions

reactions that release energy

endothermic

reaction that require energy to proceed

How enzymes act as catalysts

1. substrate enters the active site to change the shape

2. active site acts to speed up the reaction by:

- acting as a template for substrate orientation

- stressing the substrates and stabilizing the transition state

- providing a favourable microenvironment

- participating directly in the catalytic reaction

3. substrates converted to products

4. products are released

5. active site available for two new substrate

enzyme are able to:

control a single type of chemical reaction, so if it isnt working (inactivated) entire pathway will quit working

metabolic regualtion

specific molecules regulate enzymes in order to promote or inhibit certain chemical reactions

competitive inhibition

an inhibitor molecule is similar enough to a substrate that it can bind to the enzymes active site to stop it from binding to the substrate

non-competitive inhibitor

inhibitor molecule binds to the enzyme at a location other than the active site (allosteric site)

- changes the shape of the enzyme so no longer optimal position to catalyze

allosteric activators

increase reaction rates

- bind to allosteric site which induces a conformational change that increases the affinity of the enzymes active sit for its substrate

feedback inhibition

when a reaction product is used to regulate its ow further production

what do we require ATP for?

any time we wither build or breakdown something through a reaction in the body

what re the 4 major macromolecular groups

carbohydrates

lipids

proteins

nucleic acids

what is the most common source of energy used to fuel the body?

carbohydrates

what does sugar catabolism do?

break polysaccharides into their individual monosaccharides

what is the most common fuel for ATP production via cellular respiration?

glucose

what is most often used for energy via beta oxidation?

triglycerides

what can amino acids be used for?

building blocks of new proteins or for the production of ATP

What is the formula for cellular respiration?

C6H12O6 + 6O2 --> 6CO2 + 6H2O + energy

3 main phases to cellular respiration

glycolysis, Krebs/ TCA/ citric acid cycle, electron transport chain

glycolysis

the breakdown of glucose by enzymes, releasing energy and pyruvic acid.