#tissues notes

every cell in the body has its own specific job related to maintaining homeostasis

cells are the most basic building blocks in the hierarchy of complex structures

tissues are the fabric of the body

when 2 or more tissues combine, they form organs

type of tissue defines its function

there are 4 primary tissues

nervous tissue provides control and communication

muscle tissue gives movement

epithelial tissue lines the body cavities and organs and cover and protect the body

connective tissue provides support

histology - the study of tissues

carmine - a red dye derived from the scales of crushed-up cochineal insects, used to highlight different cell structures

nervous tissue forms the nervous system which regulates and controls the body's functions

nervous tissue senses stimuli and sends electrical impulses through the body in response to those stimuli

nervous tissue is made up of two types of neurons and glial cells

neurons sense stimuli and send messages to your brain

neurons are made up of the cell body (soma), dendrites, and the axon

cell body (soma) is the cell's life support, it has all the necessary parts like a nucleus, mitochondria, and DNA

dendrites are bushy and look like the trees that they're named after, they collect signals from other cells to send back to the soma

axon is long and rope-like, it's the transmission cable and it carries messages to other neurons and muscles and glands

glial cells provide support, insulation, protection and tether to blood vessels

muscle tissues can contract and move

the three types of muscle tissue are skeletal, cardiac, and smooth

skeletal muscle tissue attaches to all the bones in your skeleton, it pulls on the bones or skin when they contact to make your body move

skeletal tissue is made up of multinucleate and striations

cardiac muscle tissue cells are generally uninucleate meaning one nucleus, have striations

the body needs order to be able to function

epithelial tissue lines, covers, and organizes the body, creating order

proper epithelium - covers and lines the outer and inner body

glandular epithelium - forms your glands and secretes hormones and other substances

primary epithelium - protects the entire body, inside and out -covers the surface of the body when it combines with connective tissues to create skin -also lines the body cavities (pericardial, vertebral, cranial, thoracic, abdominal, and pelvic) and coats the internal and external walls of the organs

membranes covering the lungs are actually invaginations (the action or process being turned inside out or folded in on itself to form a cavity or pouch) of the epithelium

the epithelium does all this to protect your deeper layers of tissue from injury or infection

all epithelial tissues are avascular (not associated with or supplies by blood vessels), they rely on the blood supply of the supporting connective tissues around them or the materials they need

the three basic shapes of epithelial cells are the squamous, cuboidal, and columnar -squamous cells are flat, name means scale, the nucleus is flattened and easy to see, and they provide fast absorption and diffusion, and make thin membranes -cuboidal cells are cube-ish shaped, as tall as they are wide, the nucleus is circular, and they absorb nutrients and produce secretions like sweat -columnar cells are tall and thick and look like columns, the nuclei are stretched into an ellipse, and they cushion underlying tissues -the shape of each kind of epithelial cell correlates with its function

the tissue's first name is its number of layers, and its last name is the shape of the cells

layering of the cell also determines functions -simple epithelium has only one layer of cells -stratified epithelium has multiple layers set on top of each other -pseudo stratified epithelium is mostly just one layer, but the cells can be different shapes and sizes, and the nuclei can be at different levels

epithelial tissue regenerates really quickly

all of the epithelial cells are polar, meaning they have distinct sides -the apical (upper) side is exposed to either the outside of the body, or whatever internal cavity its lining -the basal (inner) side is tightly attached to the base membrane, a thin layer of mostly collagen fibers that helps hold the epithelium together, and anchors it to the connective tissue

many of the boundaries that the cells form aren't absolute, but instead selectively permeable, allowing for some form of absorption, filtration, and excretion of substances