Introductory Biology II Lab - Animal Tissues

Quiz 4

Levels

Chemical → Cellular → Tissue → Organ → System → Organism

Cell Junctions

• Desmosomes

• Tight Junctions

• Gap Junctions

Desmosomes

• adhering

• “button-like”

• strong support, but allow for intracellular channels

• intercellular connecting filaments

• disk reinforced with keratin intermediate filaments

• found in stressed tissues (heart tissue)

Tight Junctions

• impermeable

• tight intercellular junction

• no intracellular transport

• epithelial layers

Gap Junctions

• areas with rapid communication

• pores/channel that allow for transport across intracellular space

• great for electrical impulses/ion flow

4 Major Tissue Types

• epithelial

• connective

• muscle

• nervous

Epithelial Tissue

- polarity

• apical side → exposed to fluid/air

• basal side → anchored to basement membrane

• protection, secretion, metabolism, sensation

• epidermis, stomach lining, windpipe, kidneys

Basement Membrane

• separates dermis and epidermis

• extracellular matrix

• collagen fibers

• protective

Simple Squamous

• “leaky”

• blood vessels and alveoli of lungs

Stratified Squamous

• tougher protection

• lining of esophagus

Simple Cuboidal

• secretion

• thyroid hormones, kidney tubules

Simple Columnar

• mucosa layer of intestinal lining

• villi (increased surface area)

Pseudostratified Ciliated Columnar Epithelium

• upper respiratory track

• mucous producing goblet cells

Exocrine

secreted into ducts

Endocrine

secreted into bloodstream (ductless)

Connective Tissue

- binds and supports

- secretes a matrix (like the basement membrane)

- can be solid, liquid, or semiliquid

- 3 Connective Fibers:

• collagen - strong, sturdy

• elastin - elastic

• reticular - woven sheet of collagen

Areolar/Loose

• thin, delicate

• holds organs in place

• connects epithelial tissue to other tissues

• fibroblasts (secretory)

• macrophage (immune)

Adipose

• specialized

• adipocytes store lipids

• prevents heat loss

• cushions

• nutrient storage

Fibrous/Dense

• thick matrix/network of collagen fibers

• parallel structure → tensile strength

• regular → extremely tightly packed (tendons/ligaments)

• irregular → interwoven bundles, less tight (dermis)

Cartilage

• dense collagen fibers

• matrix → chondroitin sulfate

• secreted by chondrocytes in lacuna spaces

• embryonic skeleton

Elastic Cartilage

• elastic fibers

• flexible support

• ears, esophagus

Hyaline Cartilage

• lacks elastin

• rigid support

• tracheal wall rings

Fibrocartilage

• has chondrocytes throughout

• wavy

• intervertebral discs

Bone

• mineralized connective tissue

• rigid matrix

• alive

Bone Lifecycle

• osteoblasts deposit calcium phosphate and collagen

• magnesium is added to form hydroxyapatite

• calcium hardens; collagen prevents brittleness

• haversian canals contain blood vessels and nerves

• osteocytes → trapped

• osteoblasts → maintain bone tissue

Types of Bone

- compact bone

• rigid

- spongy bone

• irregular trabeculae

• red marrow

• less rigid than compact bone and no osteons

Cellular Components of Blood

- erthrocytes

• make up 45% of blood

• most numerous

• denucleated in mammals

• important for gas exchange

• short lived

- leukocytes

• amoeboid movement

• two main groups: Granulocytes and Agranulocytes

Granulocytes

- neutrophils

• most common WBC

• 3-5 nucleus lobes

• phagocytosis

- eosinophil

• 2-5%

• bilobed nucleus; red cytoplasm

• phagocytosis; allergic reactions; parasitic worm infections

- basophils

• rarest (0.5%)

• “S” shaped nucleus

• dark purple cytoplasm

• releases histamines

Agranulocytes

- monocytes

• 3-5%

• largest

• horseshoe nucleus

• wandering macrophages

- lymphocytes

• 20-25%

• spherical purple nucleus

• immunological memory

Skeletal Muscle

• muscular tissue

• attached to bone

• voluntary

• fastest contraction

• striated

• myofibrils (make up each muscle fiber; actin and myosin)

• multinucleated

• unbranched

Cardiac

• striated

• branched

• connected by intercalculated discs

• heart

• single nucleus

Smooth

• no striations

• spindle shaped

• sphincters

• glands/arteries/veins

• slowest

Neurons

• axons → send message

• dendrites → receive message

• soma (body) → process information, maintain cell health, and generates energy

• node of ranvier

• axon terminal

• nucleus

• myelin sheath

• schwann cell