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Anatomy of Cells. “Typical” Cell. “Typical” Cell vs. Reality. “Typical” cells do not actually exist in the body Cell are specialized structure to carry out specialized functions (see Table 3-1, pg. 73) Nerve cells: have long extension transmit nerve impulses throughout the body
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“Typical” Cell vs. Reality • “Typical” cells do not actually exist in the body • Cell are specialized structure to carry out specialized functions (see Table 3-1, pg. 73) • Nerve cells: have long extension transmit nerve impulses throughout the body • Muscle cells: contain fibers that slide together contracts/movement of body parts • RBCs: contain hemoglobin carry oxygen from lungs to various parts of the body
Main Components of Cell Structure • Plasma Membrane • Cytoplasm • Cytosol (intracellular fluid) • Organelles • Nucleus • Cytoskeleton • Cell’s internal supporting framework
Plasma Membrane • Phospholipid bilayer • Hydrophilic heads • Hydrophobic tails • Majority of membrane is hydrophobic – water and water-soluble molecules cannot pass • Cholesterol – steroid lipid; provides stabilization for the plasma membrane
Plasma Membrane • Embedded proteins • Penetrate into the hydrophobic regions of the plasma membrane • Transport mechanism • Transport proteins are often specific for certain molecules • “Gates” can open or close
Plasma Membrane • Peripheral Proteins • Glycoproteins (carbohydrates and proteins) • Identification markers • Recognize self vs. non-self (immune system) • Receptors • Proteins that react in the presence of hormones or other regulatory chemicals • Trigger metabolic changes within the cells • Signal transduction
Cytoplasm • Cytosol • Watery solution • Intercellular fluid (ICF) • Organelles • “tiny organs” • Thicken the cytosol to a gel-like consistency
Endoplasmic Reticulum • Rough ER • Presence of ribosomes • Protein synthesis • Intracellular transport • Smooth ER • Lipid and carbohydrate synthesis • Replenishes cell membrane material http://micro.magnet.fsu.edu/cells/endoplasmicreticulum/images/endoplasmicreticulumfigure1.jpg
Ribosomes • Attached to Rough ER or scattered throughout cytoplasm • Composed of a large and a small subunit • Each subunit contains RNA (rRNA) bonded to protein • Function – Protein synthesis • Cell’s “protein factory”
Golgi Apparatus • Consists of tiny sacs or cisternea • “processing & packaging plant” • Export proteins make in the Rough ER out of the cell • Secretion • Fig 3-5, page 81
Lysosomes • Vesicles that have pinched off from the Golgi apparatus • Contain enzymes capable of breaking down cell components • “digestive bags” or “cellular garbage disposals” • Ex: rid cells of bacteria; Scavenger WBCs
Peroxisomes • Similar to lysosomes • Small sac containing enzymes • Important in kidney and liver cells • Detoxification functions in the body
Mitochondria • Structure: • Two membranes (sac within a sac) • Inner membrane contains folds (cristae) • Function: • Enzymes embedded in cristae – essential in making adenosine tri-phosphate (ATP) • Cell “power plant” • # of mitochondria based on amt of work done by cell • Ex: liver cells > sperm cells • Self-replicating – based on energy needs • Aerobic exercise increases # of mitochondria in skeletal muscle cells
Nucleus • Large, spherical organelle • Enclosed by a two nuclear membranes = nuclear envelope • Nuclear pores – selectively allow molecules to enter/leave nucleus • Contains DNA (genetic information) • Chromatin – uncondensed genetic material • Chromosomes – condensed genetic material • Nucleolus – synthesizes rRNA
Cytoskeleton • Cell Fibers • Microfilaments • “Cellular muscles” • Thin, twisted strains of protein • Can contract (ex: muscle cells) • Intermediate Filaments • slightly thicker • Main component of the supporting framework in many cell types • Microtubules • Thickest of the cell fibers; tiny, hollow tubes • Cell “engine” – help with movement within the cell and the cell itself
Cytoskeleton • Centrosome • Located near the nucleus • “microtubule-organization center” • Important role in cell division – move chromosomes around the cell • Centrioles • Cylindrical structures within the centrosome • Replicate prior to cell division • Roles in cell division
Cell Extensions • Microvilli • Epithelial cells found where absorption is necessary (ex: small intestine) • Increase surface area • Cilia • Transport fluid across a cell surface • Ex: Line the respiratory tract – move mucous upward • Ex: Assist the ovum to move towards the uterus • Flagella • Single, long structures; aids in locomotion • Ex: sperm cells
Anthony’s Textbook of Anatomy and Physiology 17th Edition. Thibodeau, Gary A. PhD and Patton, Kevin T. PhD. Mosby, Inc.