Physiology Test 1

Feedback Loop

Negative Feedback Loop

A mechanism that counteracts a change in the body, promoting stability by reducing the output or activity when limits are exceeded. Maintains Homeostasis.

Positive Feedback loops

are mechanisms that enhance or amplify changes in the body, leading to an increase in output or activity until a specific event occurs. Keeps going until the outcome comes ex: birth

homeostasis

the process of maintaining a stable internal environment in the body despite external changes.

The 4 major cell and tissue types

Muscle cells and tissue, Neuron and nervous tissue, Epithelial cells and tissue, and connective cells and tissue

Muscle cell and tissue

3 types: smooth, skeletal, and cardiac that are responsible for movement and force generation in the body.

Neuron and Nervous cells and tissue

Send signal to body to get reactions

Epithelial cells and tissues

specialized for the selective secretion and absorption of ions and organic molecules, and for protection.

Connective tissue cells and tissue

Connect, anchor, and support the structure of the body: loose connective, dense connective, blood, bone, cartilage, adipose

60/40/20

60% total water in body, 40% intracellular volume, 20% extracellular volume, 15% interstitial volume, 5% plasma

Communication signals in three categories:

Endocrine, paracrine, autocrine

Endocrine

signal reaches distant targets after blood transport

paracrine

signal reacher neighboring cells via ISF

Autocrine

signal effects the cell that synthesized the signal

Chemical communication between cells that don’t require a chemical messenger.

Gap junctions and Juxtacrine signaling

Gap Junctions

allow molecules to move from one cell to an adjacent cell without entering the ECF. Jack and Jill bathroom

Juxtacrine signaling

requires 2 cells to physically touch for signal to happen

primary reactions that body uses to assemble and break down biological macromolecules

dehydration synthesis and hydrolysis

Dehydration synthesis

Putting together by removing water, combines small molecules to larger ones =, releases a molecule of water to form new chemical bond.

Hydrolysis

Breaks down large polymers into smaller monomers. A molecule of water is added splitting apart to attach the broken ends to cleave the chemical bond.

3 monosaccharides

Glucose, frustose, galactose

Glucose

main sugar your body uses for energy

Fructose

sugar found in fruits

Galactose

one of the sugars found in milk

Disaccharides

2 sugars joined together (sugrose, maltose, lactose)

Polysaccharides

Many sugar units ex: starch, glycogen, cellulose

Carbohydrates

immediate energy, limites storage, exercise

Lipids (fats)

Main source of energy when you are resting, doing low intensity tasks, or going long periods without food.

Glucose + fructose =

sucrose (table sugar)

glucose +glucose=

maltose

galactose+glucose =

lactose (milk sugar)

What is Glycogen?

How your body stores glucose for later

Where is glycogen stores:

Liver ( it’s main purpose is to maintain blood glucose) , and muscles ( when exercising your muscles can use the stored glycogen)

Your body can only store a limited amount of glycogen:

Muscle glycogen: 1,600 kcal

Liver glycogen: 400kcal

Blood glucose: 40kcal

Glucose is a simple sugar =

monosaccharide

Glycogenolyis

Breakdown process of glucose, uses hydrolysis, an enzyme called glycogen phosphorylase to cut individual glucose units from the long chain.

Lipids

main source of energy in the body, body’s multi purpose toolbox. Each lipid is made up of 3 things: carbon, hydrogen, and oxygen.

Fatty acids

The building blocks with 3 structural styles

Saturates fatty acid (bad for you)

straight piece of string, no double bonds, solid

Unsaturated fatty acids

Double bonds, wire like, liquid

Glycerides and Tryglycerides

Glycerol is the backbone where fatty acids attach to, triglycerides are 3 amino acids attached.

Triglycerides

Body’s main long term storage unit, how your body store’s extra food energy for later, degrades in mitochondria for energy.

Phospholipids

Split personality makes them perfect for creating cell membranes, physical barrier, gateway for exchange, communication, cell structure.

Steroids and eicosanoids

ex: cholesterol, cortisol; body converts cholesterol into essential signaling hormones, don’t contain any ffa, hydrophobic

Adipse tissue

The storage of fat

4 main functions of steroids

control metabolism, inflammation and immunity, salt and water balance, development of sexual characteristics

Most abundant steroid in the body

Cholesterol

Nucleic acids

Genetic code stores in genes as DNA, RNA used to decode this information to determine AA sequence.

Proteins

Primarily structure and building blocks, made of carbon, hydrogen, oxygen, nitrogen, sulfur

Important concept about proteins:

they don’t have a warehouse so they can’t be stored long-term

Proteins are constantly being:

Built, used broken down, ad recycled in organelles.

Ribosomes (protein factories)

Assemble AA chains using instructions carried by messenger RNA.

Free ribosomes (floating in cytosol)

make proteins meant to stay inside the fluid of the cell

Attached ribosomes (on rough ER)

make proteins meant to be shipped out of the cell membranes, or sent to specific organelles, packaged by golgi.

4 levels of protein folding

Primary, secondary, tertiary, and qauternary

Primary structure

linear polypeptide chain

Secondary

Cahins start to coil/fold due to hydrogen bonds: alpha helix (a corkscrew coil), Beta pleated sheets (A zig zag, like fold)

Tertiary

once secondary structure formed, associations between side chains become possible. This allows polypeptide to fold into its final 3D conformatio.

Quaternary

2 or more separate folded protein chains join together to form one big functional protein complex

Proteins made of multiple subunits

hemoglobin

What is a ligand?

any molecule or ion that physically binds to a protein (receptor)

How do they stick?

use non-covalent, reversible forces (-+) electrical charges attracting each other.

Induced fit model

The proteins binding site slightky reshapes itself to snuggle fit the incoming ligand.

Binding site

Specific pocket on folded protein where ligand fits based on shape and electrical charges.

Change of conformation:

When ligand plugs into binding site, it forces the entire protein to change it’s shape. This chnage is what turns the protein “on” or “off”, activating an enzyme opening a channel or triggering a signal.

Binding site characteristics:

Specificty, affinity, saturation, competition

Specifity (shape and change match)

The ability of a protein’s binding site to pick out and bind specific ligands.

3 requirements of specificity:

proximity (closeness), opposite charges attracting, and matching 3D shape.

Drug Specificity

Broad-binding frugs hit many protein sites across the body, causing more side effects. Highly specific drugs hit only one target site, fewer side ffects.

Affinity (binding strength)

How tightly a ligand sticks to a binding site. High affinity= tighter, requires little ligand to work, low affinity= loose, lets go easily, does the shape match.

Saturation (occupied seats)

% of total binding sites currently filled by ligands. 100% saturation every ligand is full adding more won’t increase the effect.

The % saturation depends on what two factors:

The concentration of unbounding ligands in the solution (ligand concentration) and binding affinity.

Competition (fighting for same site)

When multiple ligands try to bind to same protein site. Who wins? The ligand with higher concentration or affinity binds first.

exam example:

On saturation graph high affinity protein reaches a higher % saturation much faster than a lower ligand concentrations that a lower affinity protein.

The golden rule:

Homeostasis keeps the body compartments in a stable state, but NOT in a chemical or electrical equilibrium.

Osmotic equilibrium

Only water reaches equilibrium across fluid compartments

Chemical disequilibrium

ions and molecules are kept at different concentrations inside vs outside the cell

Electrical disequilibrium

The inside of the cell is slightlly more negative than the outside

High concentrations outside cell

sodium, calcium, chloride

High concentration inside the cell

potassium

Concentration gradient

Movement naturally goes from high to low. The steeper the difference the stronger the gradient.

3 ways to substances pass through the membrane

passive transport, active transport, vesicular transport

Passive transport

No energy, moves down concentration gradient (simple or facilitated diffusion)

Active Transport (2 types)

requires energy, moves against gradient low to high.

primary active

Direct use of ATP pumps

Secondary active

Uses the chemical gradient set up by primary transport ( includes uniport, symport, and antiport.

Uniport (passive)

move one specific molecule across the cell membrane at a time , facilitated diffusion

Symport (secondary active)

Moves two different substances in the same direction across membrane at the same time

Antiport (secondary active)

Moves two different substances in opposite directions at the same time

Simple diffusion (passive)

molecules slip directly though phospholipid bilayer without ATP, hydrophobic molecules

Facilitated diffusion (passive)

use protein channels to diffuse into cells ( sodium, potassium chloride, calcium)

Diffusion equilibrium

Net movement continues until the concentration on both sides becomes equal. Once equal molecules still move back and forth.

What do fatty acids use to get by?

Simple diffusion (lipid-soluble)

What does glucose use to get buy?

facilitated diffusion (needs a carrier protein)

Conformation changes

A conformational change is a temporary change of a protein that allows it to perform a specific function—like opening or closing a gate to move molecules across a cell membrane.

Sodium Potassium pump (primary active)

pumps 3 sodium out of cell and two potassium In to the cell per ATP molecule used

Ca2+-ATPase pump (primary active)

pumps calcium to ER

H+-ATPase pump (primary active)

found in stomach and kidney

H+/K+-ATPase pump (primary active)

found in mitochondria

Secondary active transport directions

Cotransport (symport), or Countertransport(antiport)