Anatomy Unit 2: Cell transport and tissues

Functions of the cell/plasma membrane

physical barrier that separates it from extracellular fluid (ECF)

regulates exchange of materials with ECF

sensitive to changes in ECF and the first to respond

structural support to enable cells to form tissues

exchange of materials

selective permeability: membrane allows some materials to pass in/out while excluding others

depends on size, shape, charge, lipid solubility

membrane transport

movement of substances in and out of the cell by two methods

passive transport: no energy required (high to low)

active transport: energy required (low to high)

passive transport types

diffusion

osmosis

facilitated diffusion

filtration

diffusion

particles distribute evenly within solution

down a concentration gradient/from high to low

ex: CO2 removal from cells

osmosis and types of solutions

simple diffusion of WATER

easily crosses the plasma membrane

hypertonic: water leaves the cell, cell shrinks

isotonic: water is at equilibrium

hypotonic: water enters the cell, cell swells

facilitated diffusion

substances require a protein carrier for passive transport

molecules are too large or lipid insoluble

proteins are VERY selective

filtration

solute: containing fluid is pushed from high → low pressure

water and small solutes are forced through a membrane by fluid or hydrostatic pressure

actove transport

substances too large for diffusion may have to move against concentration gradient

requires: ATP, carrier molecules, specific enzymes

exchange pump

maintains appropriate ion concentration on both sides of a membrane

exocytosis

moves materials out of cell

materials carried in a vessel out to plasma membrane and released out of cell

hormones, mucus

endocytosis and types

materials imported into cell

can be very selective, vessel will not form without recognition by receptors on surface

phagocytosis: cell eating (ex immune system)

pinocytosis: cell drinking (ex intestines taking in solutes)

tissues definition

groups of specialized cells working together to perform a function

cells of the same tissue have similar structure

types of tissues

epithelium

connective

muscle

nervous

what is epithelial tissue? and forms

tissue that covers all internal and external body surfaces, lines body cavities, makes up glands

forms boundaries in the body

covering and lining epithelium (ex skin, stomach)

glandular epithelium (ex salivary glands)

structure and surfaces

cells packed together forming sheets

cells regenerate easily

avascular: lack blood supply

apical surface: not attached to surrounding tissue

basement membrane: attached to underlying connective tissue