The Animal Body Chapter 37

Tissues: Epithelial  Cells fit tightly together to form a sheet  One side is exposed on the surface of the body or the lining of a cavity  Functions: protection, absorption, secretion, sensation  Three types of cells classified by shape: Squamous – thin, flat Cuboidal – short, cube-shaped Columnar – column-shaped  Number of layers: Simple epithelium – one layer of cells; in areas of secretion or absorption Stratified epithelium – 2 or more layers; involved in protection

Tissues: Epithelial…  Glands – one or more epithelial cells specialized to produce and secrete sweat, milk, mucus, wax, saliva, hormones, or enzymes  Types: Exocrine – secrete products onto free epithelial surface usually through a duct Endocrine – no ducts; release products (hormones) into interstitial fluid

Tissues: Connective  Supports and cushions organs  Few cells embedded in intercellular substance - fibers scattered through a matrix  Three types of fibers: Collagen – made of collagens; the most numerous; very tough Elastic – made of elastin; form networks; can return to their original shape Reticular – collagen and some glycoprotein; thin, branched fibers; thin and join connective tissue to other tissues

Types of Connective Tissue  Loose –attaches skin to muscles and lower structures  Dense – found in the lower dermis Tendons – connect muscles to bones Ligaments – connect bones to bones  Elastic – in lungs and walls of arteries  Reticular – internal supporting network for many organs

Types of Connective Tissue…  Adipose – stores fat; below skin and in tissue that cushions internal organs  Cartilage – firm yet flexible; provides shape of some organs and cushions joints  Bone – main framework in vertebrates; also involved in blood cell production  Blood and lymph – specialized cells that help body parts communicate  Muscle – allow movement Skeletal – attached to bones Cardiac – found in heart Smooth – wall of internal organs

Tissues: Nervous  Neurons – specialized for receiving and transmitting signal Cell body – main cell with two types of extensions:  Dendrites – carry info to the cell  Axons – carry info away from the cell

Organs and Organ Systems  Integumentary – covers and protects Skin, hair, nails, sweat glands  Skeletal – supports and protects Bones, cartilage, ligaments  Muscular – provides locomotion Skeletal, smooth, and cardiac muscles  Digestive – ingests and digests food Mouth, esophagus, stomach, intestines, liver, pancreas, salivary glands  Circulatory – transports materials throughout body Heart, blood vessels, blood, lymph, lymph nodes

Organs and Organ Systems…  Respiratory – gas exchange Lungs, trachea  Urinary – excretion of metabolic wastes Kidney, bladder, ducts  Nervous – receives and responses to stimuli; coordinates other systems Brain, nerves, sense organs, spinal cord  Endocrine – regulates body chemistry and function Ductless glands (pituitary, adrenal, thyroid)  Reproductive – sexual reproduction Testes, ovaries, uterus

Thermoregulation  Body heat is produced as a by-product of metabolic activity  Ectotherms – use the heat of their environment to supplement body heat Require less food; cannot survive in all climates  Endotherms – supply heat from food to maintain body temperature Require additional food; can live in more places  Acclimation – adjusting to seasonal changes in environmental temperatures (ex: dog growing thicker coat in winter)  Dormancy – a strategy to survive seasonal cold or heat Hibernation Estivation