Chapter 3a

Compartmentation: Cells and Tissues

About this Chapter

• • • • • • Body compartments Biological membranes Intracellular compartments Tissue types and characteristics Tissue remodeling Organs

Three Major Body Cavities POSTERIOR ANTERIOR Cranial cavity Pleural sac Pericardial sac Thoracic cavity Diaphragm Abdominal cavity Pelvic cavity Abdominopelvic cavity Figure 3-1

Body Cavities

Lumens of Hollow Organs

• • Hollow organs • • • • Heart Lungs Blood vessels Intestines Lumen • Not the internal environment

Functional Compartments

1. Outside Body 2. Extracellular fluid • Plasma • Interstitial fluid 3. Intracellular fluid 4. Organelles and vacuoles

Body Fluid Compartments Capillary wall Cell membrane Blood cells Blood vessel Plasma ECF Interstitial fluid Intracellular fluid Cell membrane ICF Figure 3-2

Cell Membrane: Overview

• Membranes in the body

Pericardial membrane Loose connective tissue Heart Cell The pericardial membrane is a tissue that surrounds the heart.

Seen magnified, the pericardial membrane is a layer of flattened epithelial cells supported by connective tissue. Each cell of the pericardial membrane has a cell membrane surrounding it.

The cell membrane is a phospholipid bilayer.

Figure 3-3

Cell Membrane: Functions

• • • • Physical barrier Gateway for exchange Communication Cell structure

Cell Membrane: Structure

• The fluid mosaic model of a biological membrane

Carbohydrate group of glycoprotein Carbohydrate group of glycolipid Extracellular surface of membrane Membrane splits into layers in freeze-fracture electron microscopy.

Proteins Intracellular surface of membrane Cholesterol molecules insert themselves into the lipid layer.

Lipid tails form the interior layer of the membrane.

Phospholipid heads face the aqueous intracellular and extracellular compartments.

Figure 3-4

Cell Membrane: Composition

• Lipids • • • Phospholipids Sphingolipids Cholesterol • Proteins • Integral • • Peripheral Lipid-anchored

Cell Membrane: Composition Table 3-1

Cell Membrane: Structure and Formation

•

Phospholipids

have polar and non-polar regions

(a) Phospholipid molecules have polar heads and nonpolar tails.

The “R” group is a variable polar group.

Structural model Polar head (hydrophilic) Nonpolar fatty acid tail (hydrophobic) Molecular models Stylized model Figure 3-5a

Cell Membrane: Formation

• Membrane phospholipids form bilayers, micelles, or liposomes

Phospholipids arrange themselves so that their nonpolar tails are not in contact with aqueous solutions such as extracellular fluid.

(b) Phospholipid bilayer forms a sheet.

Tails Micelles are droplets of phospholipids.

Liposomes have an aqueous center. Figure 3-5b

Cell Membrane: Proteins

• The three types of membrane proteins: integral, peripheral, and lipid-anchored

Integral (transmembrane) protein Glycoprotein Peripheral protein Peripheral protein Cytoskeleton proteins Lipid-anchored proteins

Cytoplasm

Figure 3-6

Cell Membrane: Lipid Rafts

• Sphingolipids and alkaline phosphatase

Figure 3-8

Cell Membrane Components Cholesterol CELL MEMBRANE

consists of

Phospholipids, Sphingolipids Carbohydrates

together form

Lipid bilayer

functions as

Selective barrier between cytosol and external environment

together form

Glycolipids Structural stability

whose functions include

Cell recognition

together form

Glycoproteins Immune response Proteins Figure 3-9

Intracellular Compartments

• • Cytoplasm • • • Cytosol Inclusions Organelles Nucleus

Cell Compartments

• A map for the study of cell structure

THE CELL

is composed of

Cell membrane Nucleus Cytoplasm Cytosol Membranous organelles • Mitochondria • Endoplasmic reticulum • Golgi complex • Lysosomes • Peroxisomes Inclusions • Lipid droplets • Glycogen granules • Ribosomes • Vaults • Proteasomes • Cytoskeleton • Centrioles • Centrosomes • Cilia • Flagella

Extracellular fluid

Figure 3-11

Inclusions Have No Membranes

• • • Ribosomes • • • Free Fixed Polyribosomes Proteasomes Vaults • RNA/protein

Cytoplasmic Proteins Fibers

• • • Actin (microfilaments) Intermediate • Myosin • • Keratin Neurofilaments Microtubules • • Tubulin Centrioles, cilia, flagella

Microtubule function

• • Centrioles • • Pull chromosomes Form core in cilia Cilia and flagella • Fluid movement

Centrioles Figure 3-13a –b

Cilia and Flagella Figure 3-13c –d

Cytoskeleton: Function

• • • • • Cell shape Internal organization Intracellular transport Assembly of cells into tissues Movement

Cytoskeleton and Cytoplasmic Protein Fibers (a) Microvilli increase cell surface area. They are supported by microfilaments.

Microfilaments form a network just inside the cell membrane.

Microtubules are the largest cytoskeleton fiber.

Intermediate filaments include myosin and keratin.

(b) Figure 3-14

Cytoskeleton and Cytoplasmic Protein Fibers

• Motor proteins move on cytoskeletal fibers

Organelle Motor protein ATP Direction of movement Cytoskeletal fiber Figure 3-15

Mitochondria

• • • Membrane-enclosed compartments Unique DNA Site of cellular ATP generation

Mitochondria Matrix is the innermost compartment.

Inner membrane Outer membrane Cristae The intermembrane space forms a compartment.

Cytosolic side of membrane Matrix Cytoplasm of cell Figure 3-16

Endoplasmic Reticulum (ER)

• • Smooth ER • • Synthesis of fatty acids, steroids, lipids Modified forms in liver, kidney, muscles Rough ER • • Rows of ribosomes Protein assembly and modification

Endoplasmic Reticulum Ribosomes are attached to cytosolic side of rough endoplasmic reticulum.

Endoplasmic reticulum Lumen of endoplasmic reticulum Smooth endoplasmic reticulum Figure 3-17