Lecture 2 Animal Cells and Tissues Mrs. Higgins, LVT Locust Trace Agriscience Center Veterinary Assistant Program

The Cell “Cells” construct ALL living things, both plants and animals Ameba – single cell (simplest creature) Capable of performing all functions commonly associated with life Functions of the cell Growth = increase in size Metabolism = use of food Response to stimuli = moving toward light Contraction = shortening in one direction Reproduction = development of new individuals of the same species

Typical cell consists of 3 main parts Cytoplasm Nucleus Cell membrane Figure 2.1

The Cell Cells – tissues – organs - systems – animal Example: cells that specialize in holding structures together make up connective tissue. Tissue with a common function make organs A group of organs that share a common function make up systems Stomach, liver, pancreas, and intestines = digestive system

Primary Types of Tissues Epithelial – cover the surface of body, line body cavities, and form glands Connective – support and bind other tissues together Muscle – specialize in contracting Nervous – conducts impulses from one part of the body to another

Epithelial Cells Classified into two groups: Simple- made up of a single layer Stratified- made up of many layers Can be further broken down within each category: Simple Squamous (plate-like) Cuboidal (cubic) Columnar (cylindrical) Pseudostratified columnar Stratified Squamous Columnar Transitional

Epithelial Cell Simple (one) Squamous Coverings of viscera and linings of body cavities and blood vessels Cuboidal Found in ducts and may have glands Columnar Honeycomb, have cilia, cells line the trachea Pseudostratified columnar Found in upper respiratory tract, cells different length, but still one layer Stratified (many) Forms outer layer of skin pharynx and salivary ducts Transitional Lining of portions of urinary system that are subjected to stretching

Special Glandular Epithelial Cells Specialized for secretion or excretion Secretion: release from the gland cell of a substance that has been synthesized by the cell that affects other cells Excretion: expulsion of waste products from the cell Glands are either endocrine or exocrine Endocrine: No ducts, empty directly into blood stream (hormones) Exocrine: empty their secretions onto epithelial surfaces, have ducts (scattered throughout body)

Connective Tissue Serves to connect other tissues Give form & strength to many organs and often provide protection and leverage Classified into the following categories: Elastic Collagenous (white fibrous) Reticular (netlike) Adipose (fat) Cartilage Bone

Connective Tissue Connective Tissues Description Elastic Kinked fibers that regain original shape after being stretched Collagenous Found throughout body in various forms Reticular Consists of fine fibrils and cells, make up framework for endocrine and lymphatic system Adipose Forms when connective tissue cells (adipocytes) store fat as inclusion within the cytoplasm Most often white or yellowish in color Cartilage Firm but not as hard as a bone, three types of cartilage (chondrocytes) Ex: ears and joints Bone Produced by bone forming cells, osteoblasts. Can form in a sponge like network to make spongy bone or in a closely packed network to form compact bone

Muscle Tissue 3 types of muscle tissue: Skeletal Smooth Cardiac Skeletal and cardiac consist of fibers, so they are considered striated muscle

Muscle Tissues Muscle Tissue Skeletal Striated Each must have its own nerve supply, when stimulated, entire fiber contracts. (Skeletal muscle tissue and connective tissue makes up flesh of meat-producing animals) *Voluntary* Smooth Line walls of the digestive tract, blood vessels, urinary organs, and reproductive organs *Not voluntary* we can’t control these Cardiac Aka *Involuntary* Not under conscious control. Have modified muscle cells called Purkinje fibers that conduct the impulses within the heart

Nervous Tissue Neuron- nerve cell Consist of Nerve body Two or more nerve processes (fibers) Axon: nerve process that conduct impulses away from the cell body Dendrite: nerve process that conducts impulses towards the cell body Nerves – bundles of axons in the periphery

Review and Pictures What are the three main parts of the cells? ______________ Epithelial cells do what? ________________________________________________________________________ Connective tissue offers __________ to other tissues.

Review and Pictures Muscle tissues specialize in ______________. Function of nervous tissue ________________________________________________________________________

Review and Pictures Label the pictures on the handout with the correct type of cells.