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)  The plasma membrane allows some materials to pass while excluding others

(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 cycle

i)     Interphase

(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)

(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)     Basic terms

(1)  Gene

(2) Genetic code

(3) Transcription

(4) Translation

ii)    The role of RNA

(1)  tRNA

(2) rRNA

(3) mRNA

iii)  Transcription

(1)  Definition

(2) Steps

(a)  mRNA formation

(b) Editing of mRNA

iv)   Translation

Part II: Body Tissues: The Living Fabric

1)    Introduction

a)    Definition

i)     Tissue

ii)    Histology

b)   Types

i)     Epithelium

ii)    Connective tissue

iii)  Muscle

iv)   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)     Cellular shape

(1)  Squamous

(2) Cuboidal

(3) Columnar

ii)    Cellular arrangement (layers)

(1)  Simple

(2) Stratified

c)    Simple Epithelia (See Fig. 3.18)

i)     Simple squamous epithelium

ii)    Simple cuboidal epithelium

iii)  Simple columnar epithelium

iv)   Pseudostratified columnar epithelium

d)   Stratified Epithelia (See Fig. 3.18)

i)     Stratified squamous epithelium

ii)    Transitional epithelium

e)    Glandular Epithelium

i)     Endocrine glands

ii)    Exocrine 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

(2) Adipose connective tissue

(3) Reticular connective tissue

(4) Dense regular connective tissue

iii)  Cartilage

(1)  Characteristics

(2) Types

(a)  Hyaline cartilage

(b) Elastic cartilage

(c)  Fibrocartilage

iv)   Bone = Osseous tissue

v)    Blood (See Fig. 4.9 k)

4)   Nervous tissue (See Fig. 3.21)

a)    Characteristics

b)   Types of cells

i)     Neurons

ii)    Supporting cells

5)   Muscle tissue (See Fig. 3.20)

a)    Characteristics

b)   Types

i)     Skeletal muscle

ii)    Cardiac muscle

iii)  Smooth muscle