BioLab Quiz 3

Permeability

How easily substances can pass through a membrane

Selectively permeable

Allows some substances through but blocks others

Impermeable

Does not allow substances through

Freely permeable

Allows substances to pass through easily

Concentration Gradient

A difference in the concentration of a substance between 2 areas

High Concentration → Low Concentration

Active transport

Moves substances from low → high concentration

Requires energy (ATP)

Moves against the concentration gradient

Active is moving up the concentration gradient

Passive transport

Movement of substances that does NOT require energy

Moves high→low concentration

Goes down the concentration gradient

Ex. Diffusion, facilitated diffusion

Osmosis

Diffusion

Movement of particles from an area of high concentration → low concentration

No energy required

continues until equilibrium is reached

Simple diffusion

Substances move directly through the membrane

Ex. Oxygen, carbon dioxide, small lipid-soluble molecules

Facilitated diffusion

Substances move high → low but need a membrane protein to help them cross

No ATP

Still passive transport

Facilitated= proteins help

Rate of diffusion

Things that affect diffusion

Smaller molecules → diffuse faster

Larger molecules → diffuse slower

Higher temperature → faster diffusion

Lower temperature → slower diffusion

Osmosis

Movement of water across selectively permeable membrane

Water moves toward the side with the higher solute concentration

Water follows solute

Solutions and Tonicity

Solute: the substance that dissolves

Ex: salt=solute

Solvent: the substance that does the dissolving

Ex. water=solvent

Solute+solvent = solution

Hypertonic

The solution has a higher solute concentration than the cell

Water moves outside the cell → cell Shrinks

Hyper= higher solute

Hypotonic

The solution has a lower solute concentration than the cell

Water moves: into the cell → cell swells

Hypo = lower solute

Isotonic

The solute concentration is equal inside and outside the cell

Water moves in and out at equal rates

Cell stays about the same size

Iso=equal

Equilibrium

When the concentration of a substance is evenly distributed

There can still be movement of molecules, but there is no net movement in one direction

Epithelial Tissues

They are tissues that cover body surfaces

Lines organs and body cavities

Form glands

They are classified based on number of cell layers and shape of cells

Simple

One layer

Stratified

Two or more layers

Pseudostratified

Looks like multiple layers, but is actually one layer

Pseudo = fake

Squamous

Flat

Cuboidal

Cube shaped

columnar

Tall

Think column

Epithelial tissue types

SIMPLE SQUAMOUS EPITHELIUM

Simple = one layer

Squamous = flat

Function = Diffusion & Filtration

Locations: Lungs & Blood Vessels

Simple Cuboidal Epithelium

One layer of cube shaped cells

Functions: absorption and secretions

Locations: kidney tubules & glands

Simple Columnar Epithelial

One layer of tall cells

Functions: Absorption & Secretion

Locations: Digestive tract

Pseudostratisfied columnar epithelium

Looks like multiple layers, but is actually one layer

Often has cilia

Function: secretes mucus and Moves mucus/debris

Pseudostratisified = respiratory system

Stratified squamous epithelium

Multiple layers of + flat cells at the surface

Two types:

Keratinized: skin, protection, water- resistant

Nonkeratinized: mouth, esophagus

Function: protection from abrasion

Stratified = protection

Stratified cubodial epithelium

Multiple layers + cube-shaped cells

Functions: protection/secretion

Location: larger glands, some ducts

Stratified Columnar Epithelium

Multiple layers + tall cells at the surface

Function: protection and secretion Location

Location: larger ducts and some reproductive/urinary tract areas

Transitional epithelium

Special type of epithelium that can stretch

Function: allows organs to expand and contract

Location: urinary bladder, ureters, parts of urinary tract