Cells and Tissue

cells

structural unit of all living things

the nucleus

control center of the cells

nuclear envelope

allows some but not all substances to pass through it, but substances pass through it more freely than elsewhere because of its relatively large pores

nuclear membrane

encloses a jellylike fluid called nucleoplasm in which other nuclear elements are suspended

nucleoli

these are one or more small, dark staining, essentially round bodies found in the nucleus

chromatin

formed when a cell is not dividing, its DNA is carefully wound around proteins called histones to form a loose network of “beads on a string”

plasma membrane

a fragile, transparent barrier that contains the cell contents and separates them from the surrounding environment

fluid mosaic model

the model that describes the plasma membrane as a constantly changing pattern caused by some of the proteins which are free to move and bob in the lipid layer

tight junctions

are impermeable junctions that encircle the cells and bind them together into leakproof sheets

desmosomes

anchoring junctions scattered like rivets along the sides of adjacent cells

gap junctions

commonly found in the heart snd between embryonic cells; communication junctions

cytoplasm

the cellular material outside the nucleus and inside the plasma membrane; site of most cellular activities

cytosol

semitransparent fluid that suspends the other elements

inclusion

chemical substances that may or may not be present, depending on the specific cell type; most are stored nutrients or cell products

organelles

each type of organelle is specialized to carry out a specific function for the cell as a whole; “little organs”

mitochondria

supplies most of the ATP; “powerhouses” of the cell

ribosomes

tiny, bilobed, dark bodies made of proteins; actual sites of protein synthesis in the cell

endoplasmic reticulum

system of fluid-filled tunnels that coil and twist though the cytoplasm; provides a network of channels for carrying substances from one part to another; mini circulatory system

rough e.r.

all building materials of cellular membranes are firmed either in or on it; especially abundant in cells that synthesize and export proteins

smooth e.r.

functions in lipid metabolism and detoxification of drugs and pesticides

golgi apparatus

appears as a stack of flattened membranous sacs that are associated with swarms of tiny vesicles; major function is to modify, package, and ship proteins via transport vesicles

golgi vescicles

where all proteins leaving the golgi apparatus accumulate in saca

lyosomes

membranous “bags” containing powerful digestive enzymes; functions as cellular stomachs

peroxisomes

membranous sacs containing powerful oxidase enzymes that use molecular oxygen to detoxify a number of harmful or poisonous substances, including alcohol and formaldehyde

centrioles

known for generating microtubules and directing the formation of the mitotic spindle during cell division

cytoskeleton

an elaborate network of protein structures that extends throughout the cytoplasm; “bones and muscles” of a cell

cilia

whiplike cellular extensions that move substances along the surface

flagella

projections formed by the centrioles are substantially longer; only example in the human body is the sperm

fibroblast

cell that has an elongated shape; abundant rough ER and a large golgi apparatus to make and secrete the protein building blocks of these fibers

erythrocyte (red blood cell)

this cell carries oxygen in the blood; biconcave disc shaped

skeletal, cardiac, and smooth muscle cells

cells that moves organs and body parts; cells are elongated and filled with abundant contractile filaments

skeletal, cardiac, and smooth muscle cells

cells that moves organs and body parts; cells are elongated and filled with abundant contractile filaments

fat cells

cells that store nutrient; huge spherical shaped produced by a large lipid droplet in its cytoplasm

white blood cells (macrophage)

cells that fight diseases; extends long pseudopods (“false feet”) to crawl through tissue to reach infection sites

nerve cell (neuron)

cells that gather information and controls body functions; has long processes for receiving messages and transmitting them to other structures in the body

oocyte (female)

largest cell in the body; egg cell containing several copies of all organelles

sperm (male)

this cell is long and streamlined for swimming to the egg for fertilization

cell physiology

Most cells have the ability to metabolize, digest foods, dispose of wastes, reproduce, grow, move, and respond to a stimulus

solution

fluid environment on both sides of the plasma membrane

solute

components or substances present in smaller amounts

intracellular fluid

a solution containing small amounts of gases, nutrients, and salts, dissolved in water

extracellular (interstitial) fluid

the fluid that continuously bathes the exterior of our cells

isotonic solutions

solution that have the same solute and water concentrations as cells do

hypertonic solution

solution that contains more solutes, or dissolved substances, than there are inside the cells

hypotonic solution

solution that contains fewer solutes than the cell does

diffusion

process by which molecules move away from areas where they are more concentrated to areas where they are less concentrated

filtration

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

osmosis

passive movement of water molecules through a cell membrane from an area of low solute to high solute

passive processes

substances are transported across the membrane without any energy input from the cell

active processes

the cell provides the ATP that drives the transport process

active transport

requires protein carries thats interact specifically and reversibly with the substances to be transported across the membrane

sodium-potassium (Na+-K+) pump

alternately carries sodium ions (Na+) out of potassium ions (K+) into the cell. Uses ATP to energize its its protein carriers called solute pumps

Vesicular transport

moves substances into or out of cells “in bulk” without actually crossing the plasma membrane directly

exocytosis

the mechanism that cells use to actively secrete hormones, mucus, and other cell products such as cellular waste; “out of the cell”

endocytosis

includes ATP-requiring processes that engulf extracellular substances by enclosing them in a vehicle; “into the cell”

cell division

process of producing more cells for growth and repair

mitosis

process of dividing a nucleus into two daughter nuclei with exactly the same genes as the mother nucleus

interphase

phase in which the cell grows and carries on its metabolic activities

prophase

the centrioles separate from each other and move toward opposite sides of the cell, directing the assembly of a mitotic spindle between them as they move

stage of cell division where the chromosomes line up at the center of the ay between the centrioles so that a straight line of chromosomes is seen

anaphase

phase where the centromeres that held the chromatids together split ensuring each daughter cell gets one copt of every chromosome

telophase

in this stage of cell division, the chromosomes at opposite ends of the cell uncoil to become threadlike chromatin again. spindle breaks down and disappear, a nuclear envelope forms around each chromatin mass, and nucleoli appear in each of the daughter nuclei

cytokinesis

the division of the cytoplasm, usually begins during late anaphase and completes during telophase

epithelial tissue

fit closely together to form continuous sheets; have no blood supply of their own; regenerate easily if well nourishes

simple epithelia

most concerned with absorption, secretion, and filtration; usually very thin

simple squamus

this type of epithelium usually forms membranes where filtration or exchange of substances by rapid diffusion occurs

simple cuboidal

type of epithelium common in glands and ducts (i.e., salivary glands, pancreas, walls of the kidney tubules)

simple columnar

epithelium that is made up of a single layer of tall cells that fit closely together

stratified epithelia

epithelia consisting of two or more cell layers; more durable than simple epithelia

stratified squamous

most common type of stratified epithelium in the body; usually consists of many cell layers

stratified cuboidal & stratified columnar

fairly rare epithelia; found mainly in the ducts of large glands

transitional epithelium

highly modified, stratified squamous epithelium that forms the lining of only a few organs: urinary bladder, ureters, and part of the urethra

pseudostratified columnar epithelium

all of its cells rest on a basement membrane but some of its cells are shorter than others, and their nuclei appear at different heights above the basement membrane

endocrine

it directly diffuses secretions into the blood vessels that weave through the glands; ductless glands; includes the thyroid, adrenals, and pitituitary

exocrine

secretions exit through the ducts to the epithelial surface; can be both internal and external; retain their ducts

connective tissue

type of tissue that perform many functions but they are primarily involved in protecting, supporting, and binding together other body tissues

bone

composed of osteocytes sitting in cavities called lacunae; sometimes called osseous

cartilage

has abundant collagen fibers hidden in rubbery matrix with a glassy, blue-white appearance; it forms the trachea, attaches the ribs to the breastbone, and covers bone ends at joints

dense connective tissue

forms strong, ropelike structures such as tendons and ligaments

tendons

attach skeletal muscle to bones

ligaments

connect bones to bones at joints

loose connective tissue

softer and have more cells and fewer fibers than any other connective tissue type except blood

adipose tissue

protects some organs; kidneys surrounded by a capsule of fat, adipose tissue cushions the eyeballs in their sockets

blood

considered a connective tissue because it consists of blood cells surrounded by a nonliving fluid matrix called blood plasma; vascular tissue

muscle tissue

type of tissue that is highly specialized to contract which generates the force required to produce movement

cardiac muscle

muscle tissue found only in the heart wall

skeletal muscle

tissue is packaged by connective tissue sheets into organs called skeletal muscles, which are attached to the skeleton

smooth muscle

muscle tissue found in the walls of hollow organs such as the stomach, uterus, and blood cells

nervous tissue

irritability and conductivity are their two major functions as all neurons receive and conduct electrochemical impulses from one part of the body to another