BY 124L - Animal Tissues

What are the levels of organizations?

cell to tissue to organ to organ system to organism

How do cells recognize and communicate with each other?

recognize each other by the extracellular matrix and communicate through the cell membranes

What are desmosomes?

button-like welds that join opposing cell membranes, rivet cells into a strong sheet but allows substances to pass freely through the intercellular space, intracellular filaments attach the plasma membranes of both cells, found in sheets of tissue that are subjected to severe stress (heart muscle)

What are tight junctions?

intracellular junctions that are tight enough to block transport of substances through the intercellular space, specialized membrane proteins that bond cells tightly together like a set of belts, found in epithelial layers that separate two kinds of solutions

What are gap junctions?

channels or pores through membranes of two cells and across the intracellular space, allow electrical communication between cells and for the flow of ions and small molecules, found in areas like the heart where rapid communication is a necessity

What are the four tissue types?

epithelial, connective, muscular, and nervous tissue

What is epithelial tissue?

tissue that makes up coverings

What is simple?

one layer

What is stratified?

more than one layer

What is pseudostratified?

only in columnar cells, have weird column shapes

What is squamous?

flat/circular

What is cuboidal?

cube/square

What is columnar?

column/rectangle

What is simple squamous epithelium?

single layer of flattened cells, very leaky so excellent for diffusion, linings of blood vessels (alveoli of lungs)

What is stratified squamous epithelium?

several layers of flattened cells stacked upon each other, can be keratinized or non-keratinized

Where are stratified squamous epithelium tissues found?

areas that are subject to abrasion; outer layer of skin, linings of vagina, anus

What does keratinized mean?

has protein keratin that confers waterproofing and helps resist friction and bacterial invasions (outer layer of skin)

What does non-keratinized mean?

occurs in areas that stay moist but are subject to wear and tear (linings of anus, vagina, mouth, esophagus)

What is a basement membrane?

where cells are in a junction with each other

What is simple cuboidal epithelium?

found in areas where the main function is secretion, endocrine glands

What are endocrine glands?

glandular epithelium that work in groups, secrete products directly in the bloodstream (without duct)

What is stratified cuboidal epithelium?

found in areas such as the sweat glands, exocrine glands

What are exocrine glands?

glandular epithelium that work in groups, secrete products into a duct (sweat glands secreting sweat)

What are simple columnar epithelium?

found in areas such as the intestinal lining (mucosa layer), finger-like projections in intestinal lining are called villi and are involved in absorption and secretion (digestive enzymes), goblet cells

What are goblet cells?

glandular epithelium that works individually, secrete mucus that helps lubricate foodstuffs as it passes down through the intestines

What is pseudostratified ciliated columnar epithelium?

found lining the upper respiratory tract (trachea and bronchi), functions to sweep mucus and foreign objects up and out of the airway using cilia located on the luminal/apical surface of the cells

What are the matrix fiber types of connective tissue?

collagen, elastic, reticular

What is loose (areolar) connective tissue?

very thin and delicate tissue; no patter or arrangement of fibers, used to hold organs in place and to bind epithelial tissue to the underlying tissues, contains all three fibers, has fibroblasts and macrophages

What are fibroblasts?

cell type in loose areolar connective tissue; secrete the proteins of the extracellular matrix (makes fibers)

What are macrophages?

cell in loose areolar connective tissue; phagocytic, amoeboid cells that function in the immune system

What is adipose connective tissue?

fat; specialized type of loose in which adipocytes (fat cells) enlarge and store lipids

What are the functions of adipose connective issue?

insulation against heat loss, pads/cushions against injury, provides nutrient storage

What is dense regular connective tissue?

matrix is a thick interlacing matted network of collagen fibers in parallel bundles, allowing for great tensile strength; no space between fibers; tendons and ligaments

What are tendons?

not elastic but are flexible, cable-like cords that connect skeletal muscle to bone

What are ligaments?

somewhat elastic and connect bone to bone

What is dense irregular connective tissue?

matrix is a thick interlacing matter network of collagen fibers in parallel bundles, allowing for great tensile strength; has fibers in interwoven bundles with more space between them

What is submucosa?

layer between the muscle (muscularis layer) and intestinal lining (mucosa layer); compromised of dense irregular connective connective tissue

What is cartilage?

specialized form of dense connective tissue that is strong but somewhat flexible, forms embryonic supporting skeleton of vertebrates

What is chondroitin sulfate?

very dense, collage fibers embedded in a rubbery matrix; secreted by chondrocytes

What are chondrocytes?

makes cartilage; found in small chambers/spaces of the ground substance called lacuna (hole); also secrete collagen

How does cartilage form the embryonic supporting skeleton of vertebrates?

as embryo ages, the cartilage gets replaced in most areas by bone except in locations such as the ear flaps, trachea, larynx, tip of nose, and end of long bones

Replacement of cartilage with bones happen in what?

all vertebrates except Chondrichthyes (sharks and rays), Myxini (hagfish), Cephalaspidomorphi (lampreys)

What is fibrocartilage?

characterized by a scattering of chondrocytes throughout collagenous fibers (in rows); found in inter-vertebral discus

What do collagen fibers do in fibrocartilage?

give a wavy appearance

What is elastic cartilage?

high number of elastic fibers present, tissue can bounce back into shape, found in areas that need flexible support (ear, esphogus)

What is a hyaline cartilage?

characterized by lack of elastic fibers, does not have ability to bounce back into shape, found in areas that need a more rigid support (ends of the long bones, sternal ends of the ribs, cartilage rings of the trachea that help keep trachea from collapsing)

What is bone?

mineralized connective tissue with a hard, rigid matrix; remains alive, secreting a calcified matrix throughout life

How is bone made?

osteoblasts lay down deposits of calcium phosphate and collage; magnesium, calcium, and phosphate form a substance called hydroxyapatite

What do calcium salts and collagen do for bones?

calcium makes the bone hard and collagen keeps it from being too brittle; give bone strength with some elasticity

What are osteons?

basic structural unit of bone; found in compact bone

Where are NOT true osteons found?

spongy bone; has irregular latticework of thin plates of bone called trabeculae with spaces between filled with red marrow that produces erythrocytes

What are osteoblasts?

build the bone tissue; when trapped in their own matrix, become osteocytes

What are osteoclasts?

function in bone degradation

What are osteocytes?

maintain bone tissue and reside in the spaces known as lacuna, which are surrounded by the matrix secreted originally by the osteoblasts

What is special about osteocytes?

switch with osteoblasts and osteoclasts depending on what cell needs

What are Haversian canals?

channels contain blood vessels and nerves to supply and control the bone cells; run through the matrix

What is a lamella?

located concentrically around the canals that are calcified rings

What is the collective term for Haversian canal and surrounding Lamella?

osteon

What are Canaliculi?

cell extensions that are how lacuna are interconnected

What are the three types of muscle?

skeletal, smooth, and cardiac

What is skeletal tissue?

cylindrical cells, striated, multinucleated, peripheral, unbranched fibers, under voluntary control; makes up large muscle masses that attch to the bones

What does exercise do to muscle cells?

increases their size not number; adults have a fixed number of muscle cells

What is cardiac muscle?

cylindrical cells, striated, up to 2 central nuclei, branched fibers, under involuntary control; found in walls of the heart

What is special about cardiac muscle?

has branched fibers joined by intercalated discs that help speed the relaying of the stimulus for contraction from cell to cell

What is smooth muscle?

spindle-shaped cells, non-striated, single nucleus, unbranched fibers, under involuntary control; found in walls of the alimentary, genital, and urinary tracts and in the walls of arteries and veins; contractions are slower but can stay contracted longer

What is a neuron made up of?

has soma, dendrites, and axon

What is a soma?

cell body of neuron; contains the nucleus and most of the organelles

What are dendrites?

extensions that are responsible for conducting stimuluses into the soma

What is the axon?

extension that is responsible for conducting impulses away from soma

What makes up nerve fibers?

axons and dendrites together

How are nerve fibers bound together outside the central nervous system?

by connective tissue to form nerves

What do nerves do?

send messages from the sense organs to the brain and conduct impulses from the brain and spinal cord to make muscle contract