Biol 2430 Anatomy and
Physiology lab
Lab period #2
Muse s 2430 ex 2 5/9/12

Fig. 3.1 Generalized Body
Cell

Plasma Membrane
• Flexible yet sturdy barrier
• The fluid mosaic model - the arrangement of molecules within the membrane resembles a sea of lipids containing many types of proteins
• The lipids act as a barrier to certain substances
• The proteins act as “gatekeepers” to certain molecules and ions

Structure of the Plasma
Membrane

Membrane Permeability
• The cell is either permeable or impermeable to certain substances
• The lipid bilayer is permeable to oxygen, carbon dioxide, water and steroids, but impermeable to glucose
• Transmembrane proteins act as channels and transporters to assist the entrance of certain substances, for example, glucose and ions

Transport in Vesicles
• Vesicle - a small spherical sac formed by budding off from a membrane
• Endocytosis - materials move into a cell in a vesicle formed from the plasma membrane three types: receptor-mediated endocytosis phagocytosis bulk-phase endocytosis (pinocytosis)
• Exocytosis - vesicles fuse with the plasma membrane, releasing their contents into the extracellular fluid
• Transcytosis - a combination of endocytosis and exocytosis

Phagocytosis

Bulk-phase Endocytosis

The Cytoskeleton

Ribosomes

Endoplasmic Reticulum

Golgi Complex

Cell Division:
Mitosis & Cytokinesis

Dna Packaging
(Chromosomes)

Life Cycle/Cell Division
• Life cycle - 2 phases:
 Interphase - growth & usual activities
 Cell division - reproduces itself
• Cell division - 2 phases:
 Mitosis - nuclear division
 Cytokinesis - cytoplasmic division
• Occsionally, mitosis takes place without cytokinesis, resulting in a binucleate cell

Mitosis
• Produces 2 daughter nuclei that are genetically identical to the mother nucleus
• Consists of 4 stages:
 Prophase
 Metaphase
 Anaphase
 Telophase

Prophase
• Chromatin threads coil & shorten to form chromosomes, which will appear as double stranded structures connected by centromeres
• Centrioles separate & act as focal points for the spindle & asters
• Nuclear envelope & nucleus breakdown & disappear

Metaphase
• Brief stage
• Chromsomes align along metaphase plate (viewed from poles, looks like a rosette)

Anaphase
• Centromeres split
• Chromosomes separate & move to opposite ends of the cell
• “Arms” dangle behind
• Anaphase ends when movement stops

Telophase
• Basically, reverse of prophase
• Chromosomes uncoil & resume chromatin form
• Spindle breaks down & disappears
• Nuclear envelopes form around each chromatin mass

Cytokinesis
• Begins during telophase
• Cleavage furrow appears over spindle equator
• Cytoplasm gets pinched, resulting in 2 daughter cells with less cytoplasmic mass than the mother cell, but genetically identical

Mitosis Overview

Mitosis Overview

What is a Tissue?
• A tissue is a group of cells
 Common embryonic origin
 Function together to carry out specialized activities
• Hard (bone), semisolid (fat), or liquid
(blood)
• Histology is the science that deals with the study of tissues.
• Pathologist specialized in laboratory studies of cells and tissue for diagnoses

Tissues
• Tissues consist of groups of cells similar in structure & function
• 4 main types:
 Epithelial
 Connective
 Muscle
 Nervous

4 Types of Tissues
 Epithelial
• Covers body surfaces and lines hollow organs, body cavities, duct, and forms glands
 Connective
• Protects, supports, and binds organs.
• Stores energy as fat, provides immunity
 Muscular
• Generates the physical force needed to make body structures move and generate body heat
 Nervous
• Detect changes in body and responds by generating nerve impulses

Epithelial Tissues
• Cover surfaces
• Functions: protection, absorption, filtration, excretion, secretion, & sensory reception

Epithelial Tissues
• Classification - based on 2 criteria:
 Number of layers (arrangement)
 Cell shape

Epithelial Cells

Epithelial Tissues
• Alternate arrangements:
 Pseudostratified - actually simple, but cells are of varying height & nuclei lie at different levels, which gives false appearance of being stratified; often ciliated
 Transitional - stratified squamous; rounded cells have ability to slide over one another, giving an organ the ability to stretch (bladder)

Epithelial Tissues
• Characteristics:
 Cellularity - cells fit closely together to form membranes or sheets
 Polarity - always have a free surface (apical surface)
 Supported by connective tissue (basal surface)
 Avascular - no blood supply; rely on diffusion of nutrients
 Regeneration - if well nourished, they can regenerate

Epithelial Tissues
• Arrangement:
 Simple - 1 layer
 Stratified - >1 layer
• Shape:
 Squamous - scale-like
 Cuboidal - cube-like
 Columnar - column-shaped

Epithelial Tissues
• Glands:
 Endocrine - lose surface connection; excretions go directly into bloodstream or lymphatic vessels
 Exocrine - retain ducts; secretions empty through ducts onto epithelial surface

Epithelial tissues
• Simple squamous
 Single layer of flattened cells
 Disc-shaped central nuclei
 Sparse cytoplasm
 Simplest of epithelia

Epithelial Tissues
• Simple cuboidal
 Single layer of cubelike cells
 Large, spherical, central nuclei

Epithelial Tissues
• Simple columnar
 Single layer of tall cells
 Round to oval nuclei
 Can be ciliated

Epithelial Tissues
• Pseudostratified columnar
 Single layer of cells of differing heights
 Nuclei at different levels
 Can be ciliated

Epithelial Tissues
• Stratified squamous
 Several cell layers
 Basal cells cuboidal or columnar
 Surface cells squamous
(named for surface layer)

Epithelial Tissues
• Stratified cuboidal
 Typical 2 layers of cuboidal cells

Epithelial Tissues
• Stratified columnar
 Several cell layers
 Basal cells usually cuboidal
 Surface cells columnar
(named for surface cells)

Epithelial Tissues
• Transitional (relaxed)
 Resembles both stratified squamous & stratified cuboidal
 Basal cells cuboidal or columnar
 Surface cells dome-shaped or squamous, depending on amount of organ stretch

Cell Junctions
• Contact points between the plasma membranes of tissue cells
 5 most common types:
• Tight junctions
• Adherens junctions
• Desmosomes
• Hemidesmosomes
• Gap junctions

Tight Junctions
• Web-like strands of transmembrane proteins
 Fuse cells together
 Seal off passageways between adjacent cells
• Common in epithelial tissues of the stomach, intestines, and urinary bladder
• Help to retard the passage of substances between cells and leaking into the blood or surrounding tissues