NURS 8022 – Patho –Exam 1 Study Guide

NURS 8022 – Patho –Exam 1 Study Guide

Module 1 – Ch: 1-2

Cellular biology, membrane physiology, action potentials, skeletal and smooth

muscle contraction, altered cellular tissue, and biology of aging

Positive and negative feedback – what are they? Understand basics of what they do

and how they affect Physiology

• Negative feedback: promotes stability

o Cancels out the original response – original stimulus or response is cancelled

out at the end

o Body must sense a change and attempt to return to normal - restores

homeostasis o Ex: increased blood glucose – body increases insulin

production – lowers blood glucose/homeostasis is restored

• Positive feedback: promotes a change in one direction; instability;

disease o Exaggeration or more of the original response

o May be unstable or normal

o Normal Ex: oxytocin release during childbirth stimulating labor contractions;

platelets and blood

clotting cascade

Explain the structure of the membrane and the organization of its polar and

non-polar components, including lipids and proteins

• Membrane structure: phospholipid bilayer

o Negative, hydrophobic tails inward; positive, hydrophilic heads

outward o Semipermeable meaning permeable, but selective

• Proteins

o Provide selectivity to the membrane

o Integral: channels, pores, carriers, enzymes, receptors, second messengers

– spread through

entire membrane

o Peripheral: enzymes, intracellular signal mediators

• Carbohydrates

o Negative charge of carbo chains repels other negative charges

o Involved in cell-cell attachments/interactions - often act as receptors

o Play a role in immune reactions

• Cholesterol – Fat/Lipids

o Gases such as N2, O2, and CO2 (uncharged substances) can freely dissolve/Move

across the lipid region of the cell membrane, these gases are nonpolar and hydrophobic,

like the lipid region of the cell membrane, so they are able to freely pass across it

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o Present in membranes in varying amounts

o DECREASES membrane fluidity and permeability (except in plasma

membrane) o INCREASES membrane flexibility and stability

Cell energy and ATP production basics

• Breakdown of carbs into glucose, proteins into amino acids, and fats into fatty acids

• Glucose, amino acids, and fatty acids are processed into acetyl-coA

• Acetyl-coA reacts with oxygen to produce ATP (aerobic process)

o 38 ATP created per molecule of glucose degraded

o Only 2 ATP created without oxygen (anaerobic)

• ATP is chemical fuel for cellular processes

• Adenosine + 3 phosphate groups = ATP

o Bonds between 2nd and 3rd phosphates contain abundant

energy o ATP converted to ADP produces energy

o Mitochondrial enzymes reconvert ADP and liberated phosphate

to ATP o 3 R’s: rupture, release, recycle

• 3 uses of ATP

o Membrane transport, synthesis of chemical compounds, and mechanical work

Transport of molecules through the membrane; diffusion and what affects it;

facilitated diffusion; active transport; osmosis and what it is

• Molecules transported through membrane

o Intracellular: K more abundant

o Extracellular: Na more abundant

• Membrane permeability and ion permeability

o High permeability: easily move across membrane

▪ Water (even though water is polar, bc it is such a small molecule it

can move freely across cell mem via protein or slipping btw the lipid tails

itself), carbon dioxide, oxygen

o Low permeability: more difficult to move across membrane

▪ Chloride, potassium, sodium

• Ion permeability

o Conductance: depends on probability that channel is

open o Characteristics:

▪ Un-gated (passive movement): determined by size, shape, distribution of charge

▪ Gated:

• voltage (ex: voltage dependent Na channels)

• Chemically (ex: nicotinic ACh receptor channels) - substance binds to open gate

• Diffusion: movement of ions/substances/molecules

o Passive: down a concentration gradient from higher concentration to lower

o Active: against concentration gradient from an area of lower concentration to higher

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o Will not occur if the membrane is non-permeable to the molecule

▪ Na and K will naturally want to diffuse in and out but cannot without

channels because they are not permeable through the membrane

o Lipid soluble (non-charged) substances move more

readily o No energy required; no carrier required o

Factors that affect net rate of diffusion:

▪ 1. concentration difference

▪ 2. electrical potential – charge difference on each side of membrane

▪ 3. pressure difference – higher pressure results in increased energy to

cause net movement from high to low pressure

• Facilitated diffusion (a type of passive diffusion): molecules move down its concentration

gradient via a carrier or channel protein molecule that facilitates its passage

o Diffusion depends on concentration of the carrier molecule – can

reach Tmax depending on concentration of the carrier molecule

o Does not move against electrochemical

gradient o No energy required

• Osmosis (a type of passive diffusion): movement of fluid across a membrane;

passive transport from an area of lower solute

concentration into an area of higher solute concentration

o Water moves down it’s concentration gradient

o Osmotic pressure: difference in solute concentration across the membrane

creates osmotic

pressure difference – this is driving force for movement of

water o Hypotonic (low solute); hypertonic (high solute)

o Osmosis stops when enough fluid has moved through the membrane to

equalize the solute

concentration on both sides of the membranes

• Active transport-uses Carrier proteins

o Primary active transport: molecules are pumped against a concentration

gradient at the expense of energy (ATP)

▪ Direct use of energy

o Secondary active transport: transport driven by the energy stored in the

concentration gradient of another molecule or driver molecule (often Na+)

▪ Created originally by primary active transport – indirect use of energy

• PRIMARY ACTIVE TRANSPORT EXAMPLES

▪ PRIMARY ACTIVE TRANSPORT

▪ Carrier protein located on the plasma membrane of all cells

▪ Na/K ATPase = enzymes that converts ATP to ADP to release energy

▪ Regulates osmotic balance by maintaining Na+ and K+ balance –

preventing cells

from swelling and bursting

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Version 2021
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