Chapter 28 Overview of Tissues

A. The Hierarchy of Structural Organization Anatomy – structure Physiology – function Structure and function are related in Biology.

For example: Molecules  cells  tissues  organs  systems  organism Protein  muscle cell  muscle tissue  heart  cardiovascular system  animal

Tissue: similar cells that perform a common function Organ: structure made of two or more types of tissue that together perform a specific task Organ system: multiple organs that together perform a vital body function

B. Stem Cells Specialized cells that start off as generic cells and become specialized.

C. There are four main types of animal tissues: Epithelial Connective Muscle Nervous

Epithelial tissue: sheets of tightly packed cells that cover body surfaces and line internal organs & cavities - Cover both inner and outer surfaces of internal organs

Layer Cell Shape Location & function Simple (single layer) Squamous (floor tiles) capilary and air sac lining Great for diffusion Cuboidal (like dice) kidney tubules and thyroid gland secretes Columnar (like bricks on end) intestinal lining Secretes Stratified (more than one) Skin Takes a beating/ regenerates fast sweat and mammary glands pharynx and anus Pseudostratified (one layer but looks like more) upper respiratory

2. Connective tissue binds and supports other tissues Contains fewer cells, scattered throughout an matrix Matrix: Secreted by the cells Contains a web of fibers embedded in a liquid, jelly, or solid Non- living Made from collagen, and elastin CFLABB

Types Loose connective tissue: binding and packing material to hold organs in place Fibers are mainly loosely woven collagen and elastic Fibrous connective tissue: tendons and ligaments Fibers are densely packed bundles of collagen

Adipose tissue: pads and insulates the body and stores energy Stores fat within cells Little matrix Cartilage: shock absorber in joints, nose, and ears Many collagen fibers embedded in a rubbery matrix

Bone: support structure Blood: functions in transport and immunity Collagen fibers embedded in a hard mineral matrix of calcium, magnesium, and phosphate Blood: functions in transport and immunity Consists of cells suspended in a liquid matrix (plasma) red blood cells (RBCs or erythrocytes) white blood cells (WBCs or leukocytes) platelets

3. Muscle tissue functions in movement Muscle tissue bundles of muscle cells Most abundant tissue in most animals In cytoplasm of muscle, large amounts of contractile proteins. (uses ATP from Mito to fuel proteins.)

Types Cardiac muscle Skeletal muscle Forms the heart Cells are striated and branched Cells connect at specialized junctions for coordinated contraction Involuntary Skeletal muscle Attached to bones by tendons voluntary body movements Striped or striated appearance

Smooth muscle Lacks striations Responsible for involuntary organ motions Ex: intestinal movements (peristalsis)

4. Nervous tissue forms a communication network Nervous tissue: senses stimuli and quickly transmits information from one part of the animal to another

Structure Neuron: Specialized to conduct electrical impulses Dendrites convey information toward the neuron cell body Axons convey information away from the neuron cell body Nervous tissue also includes supporting cells

D. Organs made up of tissues DERNCRIMUILS

Organ systems work together to perform life’s functions Skeletal: supports the body allows movement Endocrine : secretes hormones to regulate body functions

Circulatory: exchanges nutrients, gases, and wastes Respiratory : exchanges gases with the environment

Muscular : produces movement and heat Integumentary : protects against injury, infection, and dehydration

Immune : defends against infection and cancer Lymphatic : provides fluid balance and immunity

Digestive : ingests, breaks down, and absorbs nutrients Urinary : excretory; removes wastes from the blood

Reproductive : initiates and supports developing embryos Nervous : detects, interprets, and directs response to stimuli

E. Animals regulate their internal environment Regulating both internal & external An animals internal environment is the interstitial fluid that surrounds the cells. Internal salt and water balance and blood temperature must be kept stable Homeostasis: maintaining a “steady state” internal environment There are always slight fluctuations

Homeostasis depends on negative feedback Negative feedback: a change in a variable triggers mechanisms that reverse that change Analogous to a thermostat that controls a furnace Many animal control centers are located in the hypothalamus of the brain Shivering and sweating are ways of controlling human body temperature