Anatomy and Physiology Unit 6

The Generalized Cell

Main Parts of the Cell Cell membrane – outer protective covering, semipermeable Cytoplasm – semi-fluid inside the cell, site for chemical reactions Organelles – cell structures that help a cell to function, located in cytoplasm Nucleus – the “brain” of the cell – controls cell activity and is vital for cell division

Parts of Cell Cont. Chromatin – in nucleus made of deoxyribonucleic acid (DNA) and protein. Forms chromosomes in cell reproduction Each human cell has 46 chromosomes (23 pairs) Centrosome – in cytoplasm near nucleus, creates an even division of the chromosomes in two new cells Mitochondria – rod shaped organells, “powerhouses” of cells, break down carbs, proteins and fats to make ATP (energy source of cells) Golgi apparatus – stack of membrane layers in cytoplasm, it produces, stores and packages secretions for discharge from the cell. Endoplasmic reticulum – network of tubular structures located in cytoplasm, transports materials into and out of nucleus, aids in synthesis and storage of proteins. Rough ER – contains ribosomes – sites for protein synthesis (production) Smooth ER – no ribosomes (not present in all cells) – assists with cholesterol synthesis, fat metabolism and detoxification of drugs Lysosomes – oval or round bodies in cytoplasm, contain digestive enzymes that digest and destroy old cells, bacteria, and foreign materials (important for immune system) Pinocytic vesicles – pocketlike folds in the cell membrane. Allow proteins and fats to enter the cell. When closed they form vacuoles (bubbles) in the cytoplasm

How long do cells live?

Cell Theory The cell is the smallest structural and functional living unit Organismal functions depend on individual and collective cell functions Biochemical activities of cells are dictated by their specific subcellular structures Continuity of life has a cellular basis

(a) Cells that connect body parts, form linings, or transport gases Erythrocytes Fibroblasts Epithelial cells (a) Cells that connect body parts, form linings, or transport gases Nerve cell Skeletal Muscle cell Smooth muscle cells (e) Cell that gathers information and control body functions (b) Cells that move organs and body parts Sperm Macrophage (f) Cell of reproduction Fat cell (c) Cell that stores nutrients (d) Cell that fights disease Figure 3.1

Chromatin Nuclear envelope Nucleolus Nucleus Smooth endoplasmic reticulum Plasma membrane Mitochondrion Cytosol Lysosome Centrioles Centrosome matrix Rough endoplasmic reticulum Ribosomes Golgi apparatus Secretion being released from cell by exocytosis Cytoskeletal elements • Microtubule • Intermediate filaments Peroxisome Figure 3.2

Cell Diversity Over 200 different types of human cells Types differ in size, shape, subcellular components, and functions

STOP Get a laptop Go to: http://wps.aw.com/bc_marieb_ehap_8/25/6525/1670654.cw/index.html Go to Section – Anatomy of a Generalized Cell Click on Parts of the Cell Structure Complete the exercise Show Mrs. K your screen when complete for credit