BIO 156- Module 7: Basic Histology

Microscopes

devices that produce magnified images of structures that are too small to see with the unaided eye micro = small scope =to look at

light microscopes

Light microscopes, also known as compound microscopes, are used to study stained or living cells. They can magnify the size of an organism up to 400 times and are commonly used in college labs

electron microscopes

electron microscopes use a beam of electrons instead of a beam of light, this allows for magnification up to 10,000,000 times!

how small is a human red blood cell

a human red blood cell is about eight millionths of a meter or 8 micrometers. 250 red blood cells could fit on a pinhead

what are the 2 parameters that are important in microscopy

magnification and resolving power

magnification

the process of enlarging an object in appearance

Resolution

the ability to distinguish two structures as separate

how does an electron microscope work

It passes electrons, rather than light through the specimen and can give much better resolution. the method to prepare a specimen for viewing kills it so living organisms cannot be viewed with an electron microscope

Tissue

A group of similar cells that perform the same function and share a common embryonic origin.

what are the 4 broad categories of tissues?

Connective tissue, muscle tissue, epithelial tissue and nervous tissue

CMEN

Histology

the microscopic study of tissue appearance, organization, and function

Epithelial tissue

the sheets of cells that cover exterior surfaces of the body, lines internal cavities and passageways, and form certain glands. like skin

where else is epithelial tissue found other than skin?

airways, the digestive tract, and urinary and reproductive systems. Hollow organs and body cavities that do not connect to the exterior of the body like blood vessels and serous membranes, are lined by endothelium, a type of epithelium.

function of epithelial tissues

protect the body, selectively allows the transfer of materials across its barrier. they are capable of secretion and release mucous onto their apical surface. Ex: the epithelium of the small intestine release digestive enzymes.

what are the main structural features of epithelial tissue?

cells are tightly packed together with little or no extracellular material, and the tissue has so blood vessels (avascular)

How do epithelial cells receive nutrients and oxygen

through diffusion from underlying tissues or absorption from a surface because blood vessels do not enter the epithelium

why is rapid regeneration important in epithelial tissue?

it allows damaged or dead cells the be shed and quickly replaced with new cells, especially in the airways and digestive tract.

how are epithelial tissues classified?

epithelial tissue is classified by the shape of the cells and number of the cell layers formed

what are the classifications of epithelial tissue?

Squamous= flattened and thin.

Cuboidal = boxy, as wide as it is tall

Columnar = rectangular, taller than it is wide

what is the difference between simple and stratified epithelium?

simple epithelium has one layer of cells, and ever cell rest on the basal lamina. Stratified epithelium has multiple layers, and only the basal layers rests on the basal lamina

what is pseudostratified epithelium

A single layer of irregularly shaped cells that appears to have multiple layers.

what is transitional epithelium?

A specialized type of stratified epithelium in which the shape of the cells can vary.

What are the main functions of connective tissue

To connect tissues, protect organs, defend against microorganisms, transport substances, store energy, and provide thermal insulation.

what are the 3 main components of connective tissue?

Cells, ground substances, and protein fibers, which together form the extracellular matrix.

what is the function of the matrix in connective tissue?

The matrix helps determine the tissues function. It can provide support, such as the hard, mineralized matrix in bones and connective tissue can contain specialized cells such as phagocytes, that engulf pathogens and remove cellular debris.

how is connective tissue categorized

by the characteristics of their ground substance and the types of fibers found within the matrix

what are the 3 broad categories connective tissue are classified into

Connective tissue proper, Supporting Connective Tissue, and Fluid Connective Tissue

what does Connective tissue proper include

loose connective tissue where the fibers are loosely organized, leaving large spaces in between. and dense connective tissue which is reinforced by bundles of fibers that provide tensile strength, elasticity and protection.

supporting connective tissue

bone and cartilage- provide structure and strength

Fluid connective tissue

lymph and blood, various specialized cells circulate in a watery fluid containing salts, nutrients and dissolved proteins

what kind of connective tissue is adipose (fat) tissue

loose connective tissue

what kind of connective tissue is tendons and ligaments

Dense connective tissue

what kind of connective tissue makes up hyaline cartilage, fibrocartilage and elastic cartilage

supportive connective tissue

what type of tissue is blood

a fluid connective tissue

what are the 3 types of muscular tissue in animal bodies?

smooth, skeletal, and cardiac

how do the 3 different types of muscular tissue differ

by the presence or absence of striations or bands, the number and location of nuclei, whether they are voluntarily or involuntarily controlled, and their location within the body.

does smooth muscle have striations?

NO they dont

how many nuclei does a smooth muscle cell have

one centrally located nucleus

is smooth muscle voluntary or involuntary

involuntary

what nervous system controls smooth muscle?

the autonomic nervous system

where is smooth muscle found in the body

in the walls of blood vessels and the digestive and reproductive systems

what is another name for smooth muscles

Non-striated muscles

what can cause smooth muscle to contract besides nervous system control?

location conditions in the tissues

does skeletal muscle have striations

Yes, it has striations.

what causes striations in skeletal muscle

the arrangement of the contractile proteins actin and myosin

how many nuclei do skeletal muscle cells have? and where are they located

multiple nuclei that are located along the edges of the cells

is skeletal muscle voluntary or involuntary?

Voluntary

what nervous system controls skeletal muscle?

the somatic nervous system

what is the main function of skeletal muscle?

to move bones

where is the cardiac muscle found?

only in the heart

does cardiac muscle have striations?

yes they do

how many nuclei does a typical cardiac muscle cell have?

one centrally located nucleus

is a cardiac muscle voluntary or involuntary?

involuntary

what are intercalated discs?

lines connecting neighboring cardiac muscle cells

what are the 2 main functions of intercalated discs?

they help electrical impulses pass between cells and keep neighboring cells strongly connected.

how can the autonomic nervous system affect cardiac muscle?

it can speed up or slow down the heart rate.

what are the 2 main cell groups found in nervous tissue?

neurons and glia

what is the main function of a neuron?

to receive input and send electrical information

what is the cell body of a neuron called?

the soma

what is the function of dendrites?

to receive signals

what is the function of an axon?

to carry signals away from the cell body

what are glial cells?

non-electrical support cells that help neurons function properly

what is the function of astrocytes?

to regulate the chemical environment around neurons

what is the function of oligodendrocytes?

to insulate axons so electrical impulses travel more efficiently

what do phagocytic glial cells do?

remove debris and damaged cells from the nervous tissue

why are both neurons and glia important?

both are necessary for healthy nervous tissue and a properly functioning nervous system.

what kind of tissue is lining the edge?

simple cuboidal epithelium, found in ovaries and kidneys

what kind of tissue is lining the empty space?

simple columnar epithelium

simple columnar epithelium

pseudostratified columnar epithelium WITH cilia