Lab 1 ANIMAL TISSUES

Levels of Organization Animals are multicellular heterotrophs whose cells lack cell walls. Most animals exhibit a hierarchical level of organization: Cells are organized into tissues Tissues combine to form organs Organs comprise organ systems

What is a tissue? Group of similar cells that perform a specialized function. Examples include: Bone tissue Blood tissue Muscle tissue

4 basic types of animal tissue: Epithelial Connective Muscle Nervous

Epithelial Tissue Characteristics: Cells fit closely together forming continuous sheets Apical (free) surface covers body surface or lines interior of organs Basal surface adheres to the basement membrane

Epithelial Tissue Supported by connective tissue Avascular, but innervated Have remarkable powers of regeneration Variety of functions depending on type (protection, absorption, filtration, excretion, secretion)

Epithelial Tissue Classification based on # of cell layers and shape of cells on apical surface. # of Cell Layers: Simple – one layer of cells Stratified – two or more layers Pseudostratified – simple, but appears stratified

Epithelial Tissue Cell shape on apical surface: Squamous – flattened & scale-like Cuboidal – box-like Columnar – tall & column-like

Connective Tissue Characteristics: Most are well vascularized Consists of widely-spaced cells and fibers embedded in a non-living extracellular matrix Variety of functions depending on type (support, binding other tissues, transport, defense, storage)

Muscle Tissue Characteristics: Well vascularized Packed with actin & myosin filaments Function to contract producing most types of body movements

Nervous Tissue Characteristics: Composed of two types of cells: Neurons – specialized to generate and transmit impulses; amitotic Neuroglia (glial cells) – protect, support & insulate neurons Main component of the nervous system (brain, spinal cord & nerves)

This week’s lab is devoted to histology (the study of tissues).

Exercise A: Epithelial Tissues Simple squamous epithelium Location – alveoli of lungs, lining of heart & blood vessels Function – allows diffusion of materials surface view lateral view

simple cuboidal epithelium Exercise A: Epithelial Tissues Simple cuboidal epithelium Location – kidney tubules & ducts; ovary surface Function – secretion & absorption simple cuboidal epithelium basement membrane cross section longitudinal section

Exercise A: Epithelial Tissues Simple columnar epithelium Location – lines digestive tract from stomach to the rectum Function – absorption & secretion

Exercise A: Epithelial Tissues Pseudostratified columnar epithelium Location – lining of trachea & upper respiratory tract Function – secretion & propulsion of mucus cilia ciliated cell goblet cell basal cell basement membrane connective tissue

stratified squamous epithelium Exercise A: Epithelial Tissues Stratified squamous epithelium Location keratinized type: epidermis of skin non-keratinized type: linings of esophagus, mouth & vagina Function – protection stratified squamous epithelium connective tissue Keratinized Non-keratinized

Exercise B: Connective Tissues Loose (areolar) connective tissue Location – widely distributed under epithelia Function – cushions organs Gel-like matrix Collagen fiber Fibroblast nucleus Elastic fiber

Exercise B: Connective Tissues Adipose Location – under skin; around kidneys & eyeballs; in breasts Function – supports & protects organs; insulates against heat loss; provides reserve fuel

Exercise B: Connective Tissues Dense (fibrous) connective tissue Location – tendons & ligaments Function – attaches muscle to bone (tendons) & bone to bone (ligaments)

Exercise B: Connective Tissues Hyaline cartilage Location – covers ends of long bones; nose, trachea & larynx Function – support & reinforcement Chondrocytes sitting in lacunae (cavities) Matrix packed with collagen fibers

Exercise B: Connective Tissues Bone Location – bones Function – support & protection; calcium storage; provides levers for muscles to act on; site of blood cell production Canaliculi Central canal Osteocyte sitting a in lacuna (cavity) Osteon

Exercise B: Connective Tissues Blood Location – contained within blood vessels Function – transport of gases (O2 & CO2), nutrients & metabolic wastes Red blood cells Platelet White blood cells: neutrophil monocyte lymphocyte Plasma (liquid matrix)

Exercise C: Muscle Tissues Skeletal muscle Long, cylindrical, multinucleate cells with obvious striations Location – attached to bones or occasionally to skin Function – voluntary movement Nuclei Striations

Exercise C: Muscle Tissues Cardiac muscle Branched, uninucleate cells with striations Location – walls of the heart Function – contract involuntarily to propel blood Branched cell Intercalated disc Striations

Exercise C: Muscle Tissues Smooth muscle Tapered, uninucleate, non-striated cells Location – walls of hollow organs Function – contract involuntarily to propel materials along internal passageways Nuclei Circular layer Longitudinal layer Individual muscle cell

Exercise D: Nervous Tissue Neurons cell body – contains nucleus cytoplasmic processes: dendrites – transmit impulses to cell body axon – transmits impulses from cell body Neuronal processes (axons & dendrites) Neuron nucleus Neuron cell body Neuroglia