biol 2430 anatomy and physiology lab lab period #2 muse fall 2430 ex 2 9/14/10
TRANSCRIPT
Biol 2430 Anatomy and Physiology lab
Lab period #2Muse Fall 2430ex 2 9/14/10
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 cube-
like 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