Cells. 1. Smallest living structures. 2. Basic structural and functional units of the body. 3. Derived from pre-existing cells. 4. Homeostasis.

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1 Cells The Cell The human body has about 75 trillion cells All tissues and organs are made up of cells Smallest functional unit of life Cytology Histology Cytology Epithelial cells Fibroblasts Erythrocytes (a) Cells that connect body parts, form linings, or transport gases Skeletal Muscle cell Smooth muscle cells Over 200 different types of cells in the human body! Nerve cell (e) Cell that gathers information and control body functions Cells 1. Smallest living structures Introduction 2. Basic structural and functional units of the body 3. Derived from pre-existing cells 4. Homeostasis (b) Cells that move organs and body parts Macrophage Fat cell (f) Cell of reproduction Sperm (c) Cell that stores nutrients (d) Cell that fights disease Figure 3.1 Introduction Introduction The activity of an organism depends upon both the individual and collective activity of its cells Loss of cellular homeostasis underlies virtually every disease process Non-living products Hair and fingernails Matrix Proteins Chemicals DNA Organelles 1

2 Chromatin Smooth endoplasmic Mitochondrion Cytosol Centrioles Centrosome matrix Cytoskeletal elements Microtubule Intermediate filaments Peroxisome Rough endoplasmic Golgi apparatus Secretion being released from cell by exocytosis Copyright 2010 Pearson Education, Inc. Figure Cytoplasm a. Cytosol b. Organelles c. Inclusion 3. Cellular Components Cell Membranes Surround cells and many organelles Functions: Physical isolation Regulation of exchange with external environment Sensitivity to outside environment Structural support Carbohydrate of glycocalyx Outwardfacing layer of phospholipids Inward-facing layer of phospholipids Polar head of phospholipid molecule Cytoplasm (watery environment) Integral Filament of cytoskeleton Bimolecular lipid layer containing Extracellular fluid (watery environment) Cholesterol Glycolipid Glycoprotein Peripheral Nonpolar tail of phospholipid molecule Figure 3.3 Cell Membranes Membrane Lipids Lipids, & carbohydrates self orienting phospholipids Polar heads Non-polar tails 75% Phospholipids 20% Cholesterol (by number of molecules nearly 50% of dry weight) 5% Glycolipids 2

3 Membrane Lipids Membrane Proteins Cholesterol Accounts for about 20% of the lipids Found in the center of the plasma Stiffen s Position Peripheral or integral Functions Transport channels Enzymatic functions Membrane Proteins Receptors (signal transduction) Intercellular junctions Cell to cell recognition Attachment to cytoskeleton Carbohydrate of glycocalyx Outwardfacing layer of phospholipids Inward-facing layer of phospholipids Polar head of phospholipid molecule Cytoplasm (watery environment) Integral Filament of cytoskeleton Bimolecular lipid layer containing Extracellular fluid (watery environment) Cholesterol Glycolipid Glycoprotein Peripheral Nonpolar tail of phospholipid molecule Figure 3.3 (a) Transport A protein (left) that spans the may provide a hydrophilic channel across the that is selective for a particular solute. Signal (b) Receptors for signal transduction A protein exposed to the outside of the cell may have a binding site with a specific shape that fits the shape of a chemical messenger, such as a hormone. Receptor Figure 3.4a Figure 3.4b 3

4 Extensions of the Cell Surface (c) Attachment to the cytoskeleton and extracellular matrix (ECM) Elements of the cytoskeleton (cell s internal supports) and the extracellular matrix (fibers and other substances outside the cell) may be anchored to, which help maintain cell shape Microvilli Cilia Flagella Figure 3.4c Extensions of the Cell Surface Microvilli Fingerlike extensions of plasma Increase surface area for absorption Where would you be likely to find them? Core of actin filaments for stiffening Microvillus Actin filaments Terminal web Figure 3.28 Microvilli (brush border) Cellular Extensions Absorptive cells Lacteal Goblet cell Blood capillaries Mucosa associated lymphoid tissue Intestinal crypt Muscularis mucosae Duodenal gland (b) Vilus Enteroendocrine cells Venule Lymphatic vessel Submucosa Figure 23.22b Cilia and flagella Whiplike, motile extensions on surfaces of certain cells Cilia move substances across the surface of stationary cells Longer flagella propel whole cells Where would you be likely to find these extensions? 4

5 Posterior Power, or propulsive, stroke Recovery stroke, when cilium is returning to its initial position Mucosa Esophagus Trachealis muscle Cilia line the lumen of the trachea Lumen of trachea Submucosa Seromucous gland in submucosa Hyaline cartilage Adventitia Anterior (a) Cross section of the trachea and esophagus (a) Phases of ciliary motion. Layer of mucus Cell surface (b) Traveling wave created by the activity of many cilia acting together propels mucus across cell surfaces. Figure 22.6a Figure 3.27 Cytoplasm Organelles Components Cytosol Ground substance of cell Organelles (except nucleus) Inclusion Little organs Specialized cellular compartments Specialized functions Construction and management of Most are bound by s Endo system Site of most chemical reactions in cell Chromatin Smooth endoplasmic Mitochondrion Cytosol Centrioles Centrosome matrix Cytoskeletal elements Microtubule Intermediate filaments Peroxisome Rough endoplasmic Golgi apparatus Secretion being released from cell by exocytosis Figure 3.2 Mitochondria Organelles Endoplasmic (rough and smooth) Golgi complex/body/apparatus s 5

6 Mitochondria Mitochondria Site of most ATP synthesis Very active in cells that require a lot of ATP Muscle Liver Kidney Only significant site of oxygen use within cell Enclosed by a double Power plants Have their own DNA Inherited through maternal line only Make their own Mitochondrial DNA Ribosome (a) Outer mitochondrial Inner mitochondrial Cristae Matrix Sites of protein synthesis Factories Free in cytoplasm or attached to s Composed of RNA and protein not bound Two subunits (c) (b) Enzymes Figure 3.17 Endoplasmic Reticulum Two distinct types Smooth Site of lipid and steroid synthesis, calcium regulation and drug detoxification Rough Studded with ribosomes Protein synthesis Continuous with nuclear Highways Smooth ER Nuclear envelope Rough ER (a) Diagrammatic view of smooth and rough ER Figure 3.18a 6

7 Golgi Complex Stacks of flattened sacs Associated with ER Functions Process molecules Sort Deliver Shipping and receiving Rough ER Golgi apparatus ER Phagosome Proteins in cisterna Secretory vesicle Vesicle becomes lysosome containing acid hydrolase enzymes Vesicle contents destined for exocytosis Secretion by exocytosis Extracellular fluid Figure 3.20 Golgi Complex s Very active in Pancreas Cells that secrete antibodies Round membranous sacs Bud off of the Golgi Complex Contain digestive enzymes waste disposal service Smooth ER s Endocytosis Process for bringing things into the cell Sometimes vesicles fuse with the lysosome Rough ER Vesicle Golgi apparatus Transport vesicle Figure

8 Endocytosis 1 Coated pit ingests Extracellular fluid substance. 2 Proteincoated vesicle detaches. Cytoplasm 3 Coat detach and are recycled to plasma. Transport vesicle Endosome s Phagocytosis Cellular eating Endocytosed vesicle is fused with a lysosome 4 Uncoated vesicle fuses with a sorting vesicle called an endosome. (a) 6 5 Transport vesicle containing components moves to the plasma for recycling. Fused vesicle may (a) fuse with lysosome for digestion of its contents, or (b) deliver its contents to the plasma on the opposite side of the cell (transcytosis). (b) Figure 3.12 Other roles Formation of fingers Suicide packets Diseases Tay Sachs Rheumatoid arthritis s Syndactyly Chromatin Smooth endoplasmic Mitochondrion Cytosol Centrioles Centrosome matrix Cytoskeletal elements Microtubule Intermediate filaments Peroxisome Rough endoplasmic Golgi apparatus Secretion being released from cell by exocytosis Figure 3.2 City hall Membrane bound = regulation Contains Chromatin Chromatin (condensed) Nuclear pores Cisternae of rough ER (a) Figure 3.29a 8