Chapter 3 Outline

Chapter 3: Cells & Tissues: Part I: Cells: The Living Units

1) Cells (See Fig. 3.4)
a) Definition – carry out all chemical activities needed to sustain life, cells are the building blocks of all living things
b) Cytology – study of cells
c) Tissues – when we group cells together that are similar in structure and function
d) Cell structure – cells are not all the same, all cells share general structures, all cells have three main regions: nucleus, cytoplasm, and plasma membrane
i) Plasma membrane – barrier for cell contents
ii) Cytoplasm – is the material outside the nucleus and inside the plasma membrane
iii) Cytosol – fluid that suspends other elements
iv) Organelles – metabolic machinery of the cell, “little organs” that perform functions for the cell
v) Inclusions – chemical substances such as stored nutrients or cell products
vi) Nucleus – control center of the cell, contains genetic material. Three regions: nucleolus, nuclear envelope (membrane), and nucleoli
vii) Nucleolus – the dot within the nucleus, chromatin
viii) Nuclear envelope – barrier of the nucleus, consists of a double membrane, contains nuclear press that allows for exchange of material with the rest of the cell
ix) Nucleoli – site of the ribosomes, they migrate into the cytoplasm through nuclear pores
x) Chromatin – composed of DNA and protein, present when the cell is not dividing, scattered throughout the nucleus


2) Cell (plasma) membrane
a) General characteristics
i) Selective permeability
(1) only certain objects can pass through it
(2) This permeability influences movement both into and out of the cell
ii) Living cells maintain chemical gradient

b) Structure – The Fluid Mosaic Model (See Fig. 3.2)
i) Phospholipid bilayer
(1) Hydrophilic polar head ( = water loving)
(2) Hydrophobic nonpolar tails (= water fearing)
ii) Glycolipids and cholesterol
iii) Proteins
(1) Integral
(2) Peripheral
iv) Microvilli - finger-like projections that increase the surface area for absorption

c) Membranes junctions
i) Tight junctions – impermeable junctions, bring cells together into leakproof sheets
ii) Desmosomes (See Fig. 3.3) – anchoring junctions that prevent cells from being pulled apart
iii) Gap junctions – allow communication between cells

3) The cytoplasm
a) Basic characteristics
b) Cytoplasmic organelles
i) Mitochondria (powerhouse of the cell) – change shape continuously, carry out reactions where oxygen is used to break down food, carry out reactions where oxygen is used to breakdown food, provides ATP for cellular energy
(1) Outer membrane
(2) Inner membrane = cristae
(3) Matrix
ii) Ribosomes – made of protein and RNA, sites of protein synthesis, found at two locations: free in cytoplasm, as part of the rough endoplasmic reticulum
(1) Free ribosomes
(2) Bound ribosomes

iii) Endoplasmic reticulum – ER (endo=within; plasmic=cytoplasm; reticulum= network) (See Fig. 3.18)
(1) Rough ER – RER (Granular)
(2) Smooth ER – SER (Agranular)
iv) Golgi apparatus
v) Lysosomes
vi) Peroxisomes
vii) Cytoskeletal elements
(1) Microtubules
(2) Microfilaments
(3) Intermediate filaments
viii) Centrosome and centrioles
ix) Cellular extensions
(1) Cilia
(2) Flagella

4) The nucleus
a) Basic characteristics
b) Nuclear envelope
i) Nuclear pore
ii) Nucleoplasm
c) Nucleoli
d) Chromatin (“beads on a string”)
i) Nucleosome (beads)
(1) Histones
(2) Double – stranded DNA
e) Membrane Transport – movement of substances into and out of the cell
i) Two basic methods of transport:
(1) Passive transport (See Fig. 3.10) – no energy is required
(a) Simple diffusion (See Fig. 3.9)
(i) Particles tend to distribute themselves evenly within a solution
(ii) Movement is from high concentration to low concentration, or “down a concentration gradient”
(iii) An unassisted process
(iv) Solutes are lipid-soluble materials or small enough to pass through membrane pores
(b) Facilitated diffusion – substances require a protein carrier for passive transport
(i) Transport lipid-insoluble and large substances
(c) Osmosis (See Figs. 3.8 & 3.9) – simple diffusion of water through a membrane
(i) Highly polar water molecules easily cross the plasma membrane through aquaporins
(ii) Hypertonic solution (hyper = greater than, above)
1. Higher concentration of solutes and a lower concentration of water
(iii) Hypotonic solution (hypo = less than, under)
1. Lower concentration of solutes and higher concentration of water
(iv) Isotonic solution (iso = same)
(d) Solutions and Transport
(i) Solution – homogeneous mixture of two or more components:
(ii) Solvent – dissolving medium; typically water in the body
(iii) Solute – components in smaller quantities within a solution
(iv) Intracellular fluid – inside the cell
(v) Interstitial fluid – fluid on the exterior of the cell
(e) Filtration
(2) Active transport – cell must provide metabolic energy (ATP)
(a) Substances are transported that are unable to pass by diffusion
(b) Substances may be too large
(c) Substances may not be able to dissolve in the fat core of the membrane
(d) Substances may have to move against a concentration gradient
(e) ATP is used for transport
(f) Na+/ K+ pump (See Fig. 3.11)
(g) Vesicular transport (See Fig. 3.5)
(i) Exocytosis (Exo = out of; cyt = cell; osis = process)
(ii) Endocytosis (Endo = into; cyt = cell; osis = process)
1. Phagocytosis
2. Pinocytosis
ii) Resting membrane potential
5) Cell diversity – cells that:
a) Cells that connect body parts (connective tissue)
b) Cells that cover and line body organs (skin)
c) Cells that move organs and body parts (muscle and skeletal tissue)
d) Cells that store nutrients (fat)
e) Cells that fight disease (immune system)
f) Cells that gather information and control body functions (nerve cells)
g) Cells of reproduction (sperm cells and egg cells)
6) Cell growth and reproduction
a) The cell life cycle – two major periods:
i) Interphase – cell grows, carries on metabolic processes
(1) G1 = growth phase
(2) S = Synthetic phase
(a) DNA replication = semiconservative replication (See Fig. 3.14)
(i) Unwinding of double helix
(ii) Formation of replication fork
(iii) DNA polymerase
1. leading strand
2. lagging strand
(iv) Formation of 2 double helices
(3) G2 = final phase of interphase
ii) Cell division (See Fig. 3.15) – cell replicates itself, function is to produce more cells for growth and repair processes
(1) Mitosis = Nuclear division
The phases of Mitosis:
(a) Prophase
(i) Early prophase
(ii) Late prophase
(b) Metaphase
(c) Anaphase
(d) Telophase
(2) Cytokinesis = Cytoplasmic division

b) Protein synthesis (See Figs. 3.16)
i) Protein s have many functions:
(1) Building materials for cells
(2) Act as enzymes (biological catalysts, catalysts speed up the reaction)
ii) Basic terms
(1) Gene – DNA segment that carries a blueprint for building one protein
(2) Genetic code
(3) Transcription
(4) Translation

iii) The role of RNA – essential for protein synthesis
(1) tRNA (Transfer RNA)
(a) Transfers appropriate amino acids to the ribosome for building the protein
(2) rRNA (Ribosomal RNA)
(a) Helps form the ribosomes where proteins are built
(3) mRNA (Messenger RNA)
(a) Carries the instructions for building a protein from the nucleus to the ribosome

iv) Transcription
(1) Definition
(2) Steps
(a) mRNA formation
(b) Editing of mRNA

v) Translation



Part II: Body Tissues: The Living Fabric

1) Introduction
a) Definition – groups of cells with similar structure and function
i) Tissue
ii) Histology

b) Primary Types
c) Epithelium
i) Locations:
(1) Body coverings
(2) Body linings
(3) Glandular tissue
ii) Functions:
(1) Protection
(2) Absorption
(3) Filtration
(4) Secretion
iii) Characteristics
(1) Cells fit closely together and often form sheets
(2) The apical (top) surface is the free surface of the tissue
(3) The lower surface of the epithelium rests on a basement membrane (like a glue)
(4) Avascular (no blood supply)
(5) Regenerate easily if well nourished

iv) Connective tissue
v) Muscle
vi) Nervous tissue

2) Epithelial tissue
a) Characteristics:
i) Cellularity
ii) Special Contacts
iii) Polarity
iv) Avascular
v) Regenerative
vi) Supported by connective tissue
b) Classification of epithelia (See Fig. 3.17)
i) Number of cell layers:
(1) Simple – one layer
(2) Stratified – more than one layer
ii) Shape of Cells:
(1) Squamous – flattened cells
(2) Cuboidal – cube-shaped
(3) Columnar – column-like

iii) Cellular arrangement (layers)
(1) Simple
(2) Stratified

c) Simple Epithelia (See Fig. 3.18)
i) Simple squamous epithelium
(1) Single layer of flat cells
(2) Usually forms membranes:
(a) Lines body cavities
(b) Lines lungs and capillaries
ii) Simple cuboidal epithelium
(1) Single layer of cube-like cells
(2) Common in glands and their ducts
(3) Forms walls of kidney tubules
(4) Covers the ovaries
iii) Simple columnar epithelium
(1) Single layer of tall cells
(2) Often includes mucus-producing goblet cells
iv) Pseudostratified columnar epithelium


d) Stratified Epithelia (See Fig. 3.18)
i) Stratified squamous epithelium
(1) Cells at the apical surface are flattened
(2) Found as a protective covering where friction is common
(3) Locations
(a) Skin
(b) Mouth
(c) Esophagus
ii) Stratified cuboidal – two layers of cuboidal cells
iii) Stratified columnar – surface cells are columnar, cells underneath vary in size and shape
iv) Stratified cuboidal and columnar:
(1) Rare in human body
(2) Found mainly in ducts of large glands
v) Transitional epithelium:
(1) Doesn’t have a single appearance
(2) Lines the bladder

e) Glandular Epithelium
i) Two major gland types:
(1) Endocrine glands:
(a) Ductless since secretions diffuse into blood vessels
(b) All secretions are hormones
(2) Exocrine glands:
(a) Secretions empty through ducts to the epithelial surface
(b) Include sweat and oil glands



3) Connective tissue (See Fig. 3.19)
a) Characteristics
i) Common tissue of origin = mesenchyme
ii) Vascularity
iii) Nonliving Extracellular Matrix ECM

b) Structural elements of connective tissue
i) Ground substance

ii) Fibers
(1) Collagen fibers
(2) Elastic fibers
(3) Reticular fibers

iii) Cells
(1) Fibroblasts
(2) Chondroblasts
(3) Osteoblasts
(4) Hematopoeitic stem cell

c) Types
i) Mesenchyme

ii) Connective tissue proper
(1) Areolar connective tissue (loose connective tissue)
(a) Most widely distributed connective tissue
(b) Soft, pliable tissue like “cobwebs”
(c) Packing tissue around organs & under skin
(d) Contains all fiber types
(e) Can soak up excess fluid (causes edema)
(2) Adipose connective tissue (loose connective tissue)
(a) Matrix: fat globules predominate
(b) Many cells contain large lipid deposits
(c) Functions:
(i) Insulates the body
(ii) Protects some organs (eyes)
(iii)
(d)
(3) Reticular connective tissue
(4) Dense regular connective tissue (dense fibrous tissue)
(a) Main matrix element is collagen fiber
(b) Fibroblasts are cells that make fibers
(c) Locations:
(i) Tendons – attach skeletal muscle to bone
(ii) Ligaments – attach bone to bone at joints
(iii) Dermis – lower layers of the skin

iii) Cartilage
(1) Characteristics
(2) Types
(a) Hyaline cartilage
(b) Elastic cartilage
(i) Provides elasticity
(ii) Supports the external ear
(c) Fibrocartilage
(i) Highly compressible to absorb shock
(ii) Forms cushion-like discs between vertebrae

iv) Bone = Osseous tissue
v) Blood (See Fig. 4.9 k)

4) Nervous tissue (See Fig. 3.21)
a) Characteristics
i) Composed of neurons and nerve support cells
ii) Function is to send impulses to other areas of the body:
(1) Irritability
(2) Conductivity
b) Types of cells
i) Neurons
ii) Supporting cells

5) Muscle tissue (See Fig. 3.20)
a) Characteristics
i) Function is to produce movement
b) Three Types:
i) Skeletal muscle
(1) Under voluntary control
(2) Contracts to pull on bones or skin
(3) Produces gross body movement or facial expressions
(4) Characteristics of skeletal muscle cells:
(a) Straited (striped)
(b) Multinucleate (more than one nucleus)
(c) Long, cylindrical
ii) Cardiac muscle
(1) Located only in heart
(2) Under involuntary control
(3) Function is to pump blood
(4) Characteristics of cardiac muscle cells:
(a) Cells are attached to other cardiac muscle cells at intercalated disks
(b) Straited (striped)
(c) One nucleus per cell
iii) Smooth muscle or visceral
(1) Under involuntary muscle
(2) Found in walls of hollow organs such as stomach, uterus, and blood vessels
(3) Characteristics of smooth muscle cells:
(4) No visible striations
(5) One nucleus per cell
(6) Spindle-shaped cells
6) Tissue Repair (Wound Healing)
a) Regeneration:
i) Replacement of destroyed tissue by the same kind of cells
b) Fibrosis:
i) Repair by dense (fibrous) connective tissue (scar tissue)
c) Neoplasm – new growth benign or malignant
d) Hyperplasia – growth due to local stimulation
e) Atrophy – decrease in size