Anatomy & Physiology (BIO 425) - Chapter 3 Cellular Form and Function2

cytology

study of cells

Robert Hooke

first to observe "small chambers" in cork and call them cells.

Schwann

concluded that all animals are made of cells and all living things arise from nonliving matter

Cell Theory

idea that all living things are composed of cells, cells are the basic units of structure and function in living things, and new cells are produced from existing cells

cell shapes

squamous, cuboidal, columnar, polygonal, stellate, spheroidal, discoid, fusiform, fibrous

micrometer (um)

a unit of length equal to one millionth of a meter 10^-6

cytoplasm

fluid between the nucleus and the plasma membrane

T.E.M.

Transmission Electron Microscope; used to study parts inside of a cell; only dead cells can be observed

resolution

the ability to clearly distinguish the individual parts of an object

S.E.M.

Scanning Electron Microscope; Scans a beam of electrons across the surface of the specimen.

plasma membrane

a semi-permeable membrane of lipids and proteins that forms the external boundary of the cytoplasm of a cell or encloses a vacuole, and that regulates the passage of molecules in and out of the cytoplasm

Cytosol or cytoplasm or intracellular fluid (ICF)

clear gel that holds the cytoskeleton, organelles, and inclusions

Extracellular fluid (ECF)

fluid outside the cells; includes intravascular and interstitial fluids

intracellular face

the side of the plasma membrane that faces the cytoplasm

extracellular face

side of plasma membrane that faces outward

Glycocalyx

Fuzzy, sugary coating formed components of glycoproteins and glycolipids; acts as an i.d. tag that enables the body to distinguish cells that should be there and shouldn't

microvilli

fingerlike extensions of plasma membrane of apical epithelial cells, increase surface area, aid in absorption, exist on every moist epithelia, but most dense in small intestine and kidney

cilia

The hairlike projections on the outside of cells that move in a wavelike manner; may be sensory (act as antennae)

axoneme

structure found in eukaryotic cilia and flagella and responsible for their motion; composed of thin protein cylinders called microtubules

basal body

anchors the cilium or flagellum

pseudopods

cytoplasm-filled extensions of the cell varying in shape from fine, filamentous to blunt fingerlike processes (amoebas, neutrophils, macrophages all move by means of pseudopods)

selectively permeable

a property of cell membranes that allows some substances to pass through, while others cannot

Passive mechanisms

-require no ATP
-random molecular motion of particles provides the necessary energy
-filtration, diffusion, osmosis

Active mechanisms

consume ATP
Active transport and vesicular transport

carrier mediated transport

use a membrane protein to transport substances from one side of the membrane to the other

filtration

physical pressure forces fluid through a semipermeable membrane (i.e. blood pressure forces fluid through gaps in the capillary wall but holds back blood cells and protein)

simple diffusion

net movement of dissolved particles down their concentration gradient

osmosis

net diffusion of water across a membrane; significant amounts pass through all areas of the membrane, but water passes easiest though aquaporins

aquaporin

channel protein through which water can diffuse across a membrane

tonicity

the ability of a surrounding solution to cause a cell to gain or lose water

hypotonic solution

lower concentration of solutes outside the cell; cells in this solution absorb H2O & may swell a burts (lyse)

hypertonic solution

higher concentration of solutes outside cell than inside; cells in this solution may shrink and shrivel (crenate)

isotonic solution

concentration of solutes outside the cell equals the concentration inside the cell

vesicular transport

large particles and molecules are transported across the membrane in vesicles

vesicles

small membrane sacs that specialize in moving products into, out of, and within a cell

endocytosis

vesicular process by which a cell takes material into the cell by infolding of the cell membrane

exocytosis

release of substances out a cell by the fusion of a vesicle with the membrane

types of endocytosis

phagocytosis, pinocytosis, receptor-mediated endocytosis

phagocytosis

process in which extensions of cytoplasm surround and engulf large particles and take them into the cell

phagosome

intracellular vesicle containing material taken up by phagocytosis.

lysosome

cell organelle filled with enzymes needed to break down certain materials in the cell

pinocytosis

process by which a cell takes in liquid from the surrounding environment

cytoskeleton

a network of protein microtubules and microfilaments that helps the cell to maintain its shape, support the cell, direct movement of materials

organelles

internal structures of a cell that carry out specialized metabolic tasks

membranous organelles

organelles isolated from the cytosol by phospholipid membranes (nucleus, mitochondria, lysosomes)

cell nucleus

largest organelle of a cell surrounded by a nuclear membrane that contains the genetic material, in form of DNA molecules organized into structures called chromosomes; genetic control center of cell activity

anuclear

not containing a nucleus (red blood cell)

multinuclear

a cell having more than one nucleus (skeletal muscle cells)

nucleoplasm

material within the nucleus; contains chromatin and one or more dark-staining masses called nucleoli where ribosomes are produced

chromatin

fine, threadlike matter composed of DNA and protein

nucleoli

dense masses of RNA and protein that manufacture ribosomes, several of these are located in the nucleus.

endoplasmic reticulum

system of interconnected channels or cisternae enclosed in a membrane

rough endoplasmic reticulum

cisternae are parallel/flat and covered with ribosomes; connected to the nucleus and and connected by bridges

produces phospholipids/proteins of the plasma membrane; synthesizes proteins (most abundant in cells that synthesize a lot of protein (antibody-producing cells)

smooth endoplasmic reticulum

cisternae are more tubular, spread out more and lack ribosomes; connected to the cisternae of the rough E.R.

abundant in cells that engage heavily in detox (liver/kidney)

ribosomes

small particles of RNA and protein found throughout the cytoplasm in all cells

"read" genetic code and produce proteins specified
unattached ones are throughout and make enzymes/proteins for use in the cell
connect to rough E.R. when they make proteins to be packaged in lysosomes or secreted out of the cell

Golgi complex

a small system of cisternae that synthesize carbohydrates and put the finishing touches on protein and glycoprotein synthesis

packages them in Golgi vesicles; some Golgi vesicles become lysosomes and some migrate to the plasma membrane to give fresh protein/phospholipids to the membrane

lysosomes

cell organelle filled with enzymes needed to break down certain materials in the cell engage in autophagy

autophagy

a process in which lysosomes decompose damaged organelles to reuse their organic monomers

mitochondria

powerhouse of the cell, organelle that is the site of ATP (energy) production

energy is not "made" but extracted from organic compounds and transferred to ATP primarily by enzymes on the cristae (small shelves on the inner of two membranes of mitochondrion)

cristae

infoldings of the inner membrane of a mitochondrion that houses the electon transport chain and the enzyme catalyzing the synthesis of ATP

centrioles

a minute cylindrical organelle near the nucleus in animal cells, occurring in pairs in a small clear area of the cytoplasm called a centrosome; involved in the development of spindle fibers in cell division

each basal body of cilium or flagellum is a single centriole perpendicular to the plasma membrane

inclusions

Accumulated cell products like glycogen or fat droplets and foreign bodies like viruses and bacteria phagotized by the cell; no membrane; not essential to cell survival

prokaryote

unicellular organism that lacks a nucleus or nuclear membrane

eukaryote

organism whose cells contain a nucleus