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A & P 3
Tissues
Question | Answer |
---|---|
cells are organized into more complex units called | tissues |
tissues | groups of cells that perform a common function |
study of tissues | histology |
four types of tissues | epithelial, connective, muscle and nervous |
epithelial tissue | covers body surfaces, lines body cavities, and forms majority of glands |
epithelial tissues acts as | physical protection, selectively permeable membrane, a source of secretions and sensations |
epithelium is classified by two-part name... | 1 - number of epithelial cell layers and 2 - shape of cells at apical surface |
simple epithelium (classification by layers) | one cell layer thick and is found where filtration, absorption, or secretion are the primary function |
example of simple epithelium | lining of air sacs of lungs, intestines and blood vessels |
stratified epithelium (classification by layers) | two or more layers of epithelial cells that are found in areas subjected to mechanical stress (better able to resist wear and tear) |
example of stratified epithelium | skin lining of the pharynx, esophagus |
pseudostratified epithelium (classification by layers) | type of simple epithelium that appears to be layered |
squamous cells (classification by cell shape) | flat, wide, irregular in shape and arranged like flattened floor tiles |
cuboidal cells (classification by cell shape) | cube-shaped |
columnar cells (classification by cell shape) | slender and taller than they are wide |
transitional cells (classification by cell shape) | change shape depending on stretch of epithelium and occur where epithelium stretches and relaxes |
example of transitional cells | lining of the bladder |
glands | individual cells or multicellular organs that are composed of predominantly epithelial tissue and secrete substances for use3 elsewhere or for elimination |
secretions of the glands | mucin, electrolytes, hormones, enzymes, and urea (nitrogenous waste) |
endocrine glands | lack ducts and secrete hormone products into intestinal fluid and blood to act as chemical messengers or influence cell activity elsewhere |
exocrine glands | connected with epithelial surface by duct |
duct | epithelium-lined tube for gland secretion |
types of exocrine gland | sweat glands, mammary glands, and salivary glands |
connective tissue | the most diverse and most widely distributed tissue, and it is designed to support, protect, and bind organs (all with proteins, protein fibers, and ground substance) |
examples of connective tissue | tendons and ligaments, body fat, cartilage, and bone, and blood |
functions of connective tissue | physical protection, support and structural framework, binding of structures, storage, transport, and immune protection |
ligaments | bind bone to bone |
tendons | bind muscle to bone |
loose connective tissue | contains relatively fewer cells and protein fibers, is an abundant ground substance, and acts as the body's packing material by supporting structures |
three types of connective tissues | areolar, adipose, and reticular |
areolar loose connective tissue | surrounds organs, nerve and muscle cells, and blood vessels |
adipose loose connective tissue | commonly known as fat |
reticular loose connective tissue | contains meshwork of reticular fibers, fibroblasts, and leukkocytes |
dense connective tissue | composed primarily of protein fibers, has proportionately less ground substance than loose connective tissue, and collagen fibers are usually the dominant fiber type |
three types of dense connective tissue | dense regular connective tissue, dense irregular connective tissue, and elastic connective tissue |
dense regular connective tissue | contains tightly packed parallel collagen fibers (resembles lasagna noodles), and is found in tendons and ligaments (with stress typically applied in a single directions), has few blood cells, and takes a long time to heal |
dense irregular connective tissue | contains clumps of collagen fibers in all directions, provides support and resistance to stress in multiple directions, and has extensive blood supply |
dense irregular connective tissue is found in... | most of the skin dermis, periosteum of bone, perichondrium of cartilage, and capsule around some internal organs (i.e. liver) |
dense elastic connective tissue | branching, densely packed elastic fibers that is able to stretch and recoil |
dense elastic connective tissue is found in | walls of large arteries, trachea, and vocal cords |
muscle tissue | cells that can contract with nervous system stimulation and cause movement (voluntary motion of body parts, contraction of the heart, and propulsion of material through digestive and urinary tracts) |
three types of muscle tissue | skeletal, cardiac and smooth muscle tissue |
skeletal muscle tissue | aka striated or voluntary muscle tissue; it is primarily responsible for movement of the skeleton and does not contract unless stimulated by somatic nervous system (considered voluntary) |
cardiac muscle tissue | responsible for heart contraction, contains visible striations, and does not require nervous system to initiate a contraction (contraction initiated by specialized cardiac muscle cells) |
smooth muscle tissue | lacks striations seen in other tissues, appears smooth, and aka visceral muscle tissue, helps to protect movement through specific organs, and considered involuntary |
where smooth muscle tissue is found... | the walls of intestines, stomach, airways, bladder, uterus, and blood vessels |
nervous tissue | located within the brain, spinal cord, and nerves, consists of cells called neurons, and conains large number of glial cells |
neurons | receive, transmit, and process nerve impulses |
glial cells | do not transmit nerve pulses, but are responsible for protection, nourishment, and support |
parts of neurons | cell body, dendrites, and the axon |
cell body | houses the nucleus and organelles |
dendrites | shorter, more numerous process that receives incoming signals and transmits information |
axon | single, long process extrending from cell body and carries outgoing signals to other cells |
organs | structure composed of two or more tissue types and work together to perform specific complex functions |
example of an organ | stomach (contains all four tissue types) |
stomach | lined by epithelium, has areolar and dense connective tissue in the walls, contains three layers of smooth muscle in walls, and has abundant nervous tissue |
purpose of epithelium in stomach | secretes substances for chemical digestion of nutrients |
purpose of areolar and dense connective tissue in walls of stomach | houses blood vessels and nerves and provides shape and support |
purpose of the three layers of smooth muscle in the walls of the stomach | contract and relax to mix materials |
purpose of nervous tissue in the stomach | responsible for regulating muscle contraction and gland secretion |
body membranes | formed by epithelial tissue bound to underlying connective tissue that lines body cavities, covers viscera, and covers body's external surface |
four types of body membranes | mucous, serous, cutaneous, and synovial |
mucous membrane | aka mucosa, lines compartments that open to the external environment (i.e. digestive, respiratory, urinary, and reproductive tracts), and performs absorptive, protective and secretory functions |
serous membrane | lines body cavities that do not open to external environment and produces a watery serous fluid that is derived from blood plasma and reduces friction between opposing surfaces |
cutaneous membrane | aka skin, covers the external surface of the body and protects internal organs and prevents water loss |
synovial membrane | lines some joints in the body, and synovial fluid is secreted by the epithelial cells to reduce friction among moving bone parts and distribute nutrients to cartilage |