Levels of Structural Organization

Cells are the smallest unit of organizationthat can live independently.

Cells are organized into tissues.

Tissues are organized into organs.

Organs are organized into systems.

Tissue—group of cells with a commonstructure and function

4 main types:

1) epithelial—outside of body, linings oforgans and cavities. Free surface isexposed to air or fluid; other side is attached to the basement membrane, adense mat of extracellular matrix.

QuickTime™ and aTIFF (Uncompressed) decompressor

are needed to see this picture.

Types of epithelialcells

simple—single layerstratified—multiple

layers

cuboidal—cube shapecolumnar—sideways

stacked brickssquamous—flat

2. Connective tissue—binds and supports

other tissues—3 types of fibers

a.collagenous fibers—nonelastic fiber (skin does not come off on pulling)

b. elastic fibers—made of elastin(guess what—they’re elastic! Skin pulls back; blood vessels)c. reticular fibers—thin, branched,made of collagen, join connective tissueto adjacent tissues (around muscle fibers)

QuickTime™ and aTIFF (Uncompressed) decompressor

are needed to see this picture.

QuickTime™ and aTIFF (Uncompressed) decompressor

are needed to see this picture.

QuickTime™ and aTIFF (Uncompressed) decompressor

are needed to see this picture.

QuickTime™ and aTIFF (Uncompressed) decompressor

are needed to see this picture.

Types of connective tissues—all have anextensive extracellular matrix

a) Loose connective tissue binds epithelial cells to other tissues, holds organs in place; ex. fibroblasts (secrete proteins), macrophages (engulf bacteria and dead cells)b) Adipose tissue stores fat, insulates bodyc) Fibrous connective tissue is made of dense collagenous fibers; ex. tendons (attach muscles to bones), ligaments (join bones together)d) Cartilage is used for flexible supporte) Bone is a mineralized connective tissue—osteoblasts deposit collagen, Ca++, Mg+, PO4

- that hardenf) Blood has a matrix of plasma

3. Nervous tissue—senses stimuli and transmits signals—functional unit is theneuron (nerve cell)

4. Muscle tissue—made of long musclefiber cells that can contract

• Skeletal—voluntary movements• Cardiac—heart muscle • Smooth—involuntary movements

Tissues are arranged into organs—many organs live in cavities filled withfluid: --lungs and heart are in thoracic cavity--stomach is in abdominal cavity

diaphragm (muscle) separates these 2cavities

Systems consist of several organs

Your systems are connected!!

Bioenergetics—howwe make energy fromwhat we eat—is itefficient?

Amount of energy an animal uses/unit time = metabolicrate

Energy is measured incalories or kilocalories

Use of chemical energy generates heat.Minimum metabolic rates maintain lifemaximum rates occur during peak activity

BMR= basal metabolic rate—for anendotherm (that’s us!) at rest, emptystomach, no stress

SMR= standard metabolic rate—forectotherms—have to know temperature

Homeostasis—”steady state”—animalswant to keep a constant condition in internal environments(ex. humans—temp, blood pH, blood sugar)

Cells ofvertebrates

live ininterstitial

fluid

Parts of a homeostatic control system:Receptor—detects a change in internal

environment

Control Center—processes informationand directs and appropriate response

Effector—effects the changes mandatedby the control center

Negative feedback is a common control mechanism