Chapter 3b

Compartmentation: Cells and Tissues

Golgi Complex

• Membranes surrounded by vesicles• Protein modification• Protein packaging into secretory vesicles

Golgi Complex

Figure 3-18a

Vesicle

Lumen

(a)

Golgi Complex

Figure 3-18b

Cytoplasmic Vesicles

• Secretory vesicles• Released from cell

• Lysosomes• Digestive enzymes

• Peroxisomes• Hydrogen peroxide• Detoxification• Fatty acid degradation

Cytoplasmic Vesicles

• Lysosomes and peroxisomes

Figure 3-19

Peroxisomes

Lysosomes

Mitochondrion

Nucleus

• Nuclear envelope• Nuclear pore complex• Chromatin • Nucleoli• Control RNA synthesis

Nucleus

Figure 3-20

Nucleolus contains DNA that controls

synthesis of ribosomal RNA.

Chromatin is DNAand protein.

Nuclear envelope is a double membrane that separates the nucleus

from the cytoplasm.

Nuclear poresregulate movementof material into andout of the nucleus.

Primary Tissue Types

• Epithelial• Lining and glands

• Connective • Protection, support and storage

• Muscle• movements

• Nervous• Communication, sense internal and external

environment

Histology

• Four types of tissues:

1) Epithelial1) Lining

2) glands

2) Connective1) Protection

2) Storage

3) connections

3) Muscle1) movement

4) Nervous1) Sense

2) communication

Epithelial Tissues: Cell Junctions and CAMs

• Cell to cell• Gap junction• Tight junction• Anchoring junction

Cell Junctions and CAMs

Table 3-3

Types of Cell-Cell Junctions

Figure 3-21a

Tight junctions preventmovement between cells.

Adherens junction

Desmosomes anchorcells to each other.

(a) Tight junction

Claudin andoccludin proteins

Intercellular space

Cell membrane

CytosolCell

1Cell

2

Types of Cell-Cell Junctions

Figure 3-21b

Tight junctionsprevent movement

between cells.

Adherens junction

Desmosomes anchorcells to each other.

(b) Desmosome, an anchoring junction

Cadherin proteins

Intercellular space

Cell membrane

Cytosol

Plaque glycoproteins

Intermediate filament

Types of Cell-Cell Junctions

Figure 3-21c

Clusters ofgap junctions

create cytoplasmicbridges between

adjacent cells.

Heart muscle hasgap junctions.

(c) Gap junction

Connexinproteins

Intercellularspace

Cell membrane

Cytosol

Cell Junctions and CAMs

• A map of cell junctions

Figure 3-22

Function

Location

Type

Membraneprotein

Cytoskeletonfiber

Matrixprotein

Actin Actin Intermediatefilaments Actin

Keratin(intermediate

filaments)

Fibronectin andother proteins Laminin

Communicating Occluding Anchoring

Cell-cell junctions Cell-matrix junctions

Gap junction Tight junction Adherens junction Desmosome Focal adhesion Hemidesmosome

Connexin Claudin,occludin Cadherin Integrin

CELL JUNCTIONS

Epithelial Tissue: Structure

• Basal lamina• Basement membrane• Cells in contact• junctions

Epithelial Tissue: Structure

Figure 3-23

Basal lamina is an acellularmatrix layer that is secreted by the epithelial cells.

Epithelial cells attach tothe basal lamina using celladhesion molecules.

Underlying tissue

Epithelial Tissue: Functions based on Layers, Shape and Features

Table 3-4

KEY

Integumentary System

Musculoskeletalsystem

Respiratorysystem

Digestivesystem

Circulatorysystem

Reproductivesystem

Urinarysystem

Cells

exchange epithelium

exchange

secretion

secretoryepithelium

protective epithelium

ciliated epithelium

transporting epithelium

Distribution of Epithelia in the Body

Figure 3-24

Exchange Epithelia

Figure 3-25a

PoreExtracellular fluid

Blood

(a) Leaky exchange epithelium allows movement through gaps between the cells.

Capillary epithelium

Transporting Epithelia

Figure 3-25b

Lumen of intestine or kidney

(b) Tight junctions in a transporting epithelium prevent movement between adjacent cells. Substances must instead pass through the epithelial cell, crossing two phospholipid cell membranes as they do so.

Extracellular fluid

Apicalmembrane

Basolateralmembrane

Tightjunction

Transportingepithelial

cell

Ciliated and Protective Epithelia

Figure 3-26a

Cilia

Microvilli

Basement membrane

Golgi apparatus

Nucleus

Mitochondria

(a) Ciliated epithelium lining the airways

Ciliated and Protective Epithelia

Figure 3-26b

Cilia

Microvilli

(b) Scanning electron micrograph showing ciliated cells mixed with cells covered with shorter microvilli

Cilia and smoking

• The following series of slides illustrate microscopic changes that happen when a person smokes.  The first slide is showing an illustrated blow-up of the normal lining of the bronchus. On the top we see the cilia, labeled (H).  They are attached to columnar cells, labeled (I).  The cilia sweep the mucous produced in the goblet cells, labeled (J) as well as mucous coming from deeper glands within the lungs and the particulate matter trapped in the mucous.  The bottom layer of cells, labeled (L) are the basal cells.

Cilia and smoking

• Below we start to see the changes that occur as people begin to smoke.  You will see that the columnar cells are starting to be crowded out and displaced by additional layers of basal cells. 

• Not only are fewer cilia present but the ones that are still functioning are doing so at a much lower level of efficiency.  Many chemicals in tobacco smoke are toxic to cilia, first slowing them down, soon paralyzing them all together and then destroying them.

Cilia and smoking

• As you see with the cilia actions being diminished, mucous starts to build up in the small airways making it harder for the smoker to breathe and causing the characteristic smokers cough in order to clear out the airways.

• Eventually though, the ciliated columnar cells are totally displaced.  As can be seen below ominous changes have taken place.  Not only is the smoker more prone to infection from the loss of the cleansing mechanism of the cilia, but these abnormal cells (O) are cancerous squamous cells.  These cells will eventually break through the basement membrane wall and invade into underlying lung tissue and often spread throughout the body long before the person even knows they have the disease.

Smoker’s lungs

Secretory Epithelia

• Goblet cells

Figure 3-27

Mucus

Basal laminaGolgi

apparatus

Nucleus

Goblet cells secrete mucusinto the lumen of hollow organssuch as the intestine.

Secretory Epithelia

• Development of endocrine and exocrine glands from epithelium

Figure 3-28

Epithelium

Connectivetissue

DuctConnecting

cells disappear

Blood vessel

Endocrinesecretory cells

Exocrinesecretory cells

Exocrine Endocrine