Chapter 3 a Compartmentation Cells and Tissues About

Chapter 3 a 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 Thoracic cavity sac 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 Interstitial fluid Intracellular fluid ECF ICF Cell membrane Figure 3 -2

Cell Membrane: Overview • Membranes in the body Pericardial Loose connective tissue membrane Cell Heart The pericardial membrane is a Seen magnified, the pericardial tissue that surrounds the heart. 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. Polar head (hydrophilic) Nonpolar fatty acid tail (hydrophobic) Structural model Molecular models Stylized model Figure 3 -5 a

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) Tails Phospholipid bilayer forms a sheet. Micelles are droplets of phospholipids. Liposomes have an aqueous center. Figure 3 -5 b

Cell Membrane: Proteins • The three types of membrane proteins: integral, peripheral, and lipid-anchored Integral (transmembrane) protein Glycoprotein Peripheral protein Lipid-anchored proteins Peripheral protein Cytoskeleton proteins Cytoplasm Figure 3 -6

Cell Membrane: Lipid Rafts • Sphingolipids and alkaline phosphatase Figure 3 -8

Cell Membrane Components CELL MEMBRANE consists of Cholesterol Phospholipids, Sphingolipids together form Lipid bilayer Glycolipids Carbohydrates Proteins together form Glycoproteins functions as whose functions include Selective barrier between cytosol and external environment Structural stability Cell recognition Immune response Figure 3 -9

Intracellular Compartments • Cytoplasm • Cytosol • Inclusions • Organelles • Nucleus

Cell Compartments THE CELL • A map for the study of cell structure is composed of Cell membrane Nucleus Cytosol Cytoplasm 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 -13 a–b

Cilia and Flagella Figure 3 -13 c–d

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

Cytoskeleton and Cytoplasmic Protein Fibers 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. (a) (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 Inner membrane Matrix is the innermost compartment. Matrix Cytoplasm of cell Outer membrane Cristae Cytosolic side of membrane The intermembrane space forms a compartment. 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