Biol 2430 Anatomy and Physiology lab Lab period #2 Muse Fall 2430 ex 2 9/14/10

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