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PowerPoint Lecture Outlines to accompany
Hole’s Human Anatomy and Physiology Eleventh Edition Shier w Butler w Lewis Chapter 2 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
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Chapter 2 Chemical Basis of Life
Why study chemistry in an Anatomy and Physiology class? - body functions depend on cellular functions - cellular functions result from chemical changes - biochemistry helps to explain physiological processes, and develop new drugs and methods for treating diseases
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Structure of Matter Matter – anything that takes up space and has weight; composed of elements Elements – composed of chemically identical atoms bulk elements – required by the body in large amounts trace elements – required by the body in small amounts Atoms – smallest particle of an element
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Atomic Structure Atoms - composed of subatomic particles:
proton – carries a single positive charge neutron – carries no electrical charge electron – carries a single negative charge Nucleus central part of atom composed of protons and neutrons electrons move around the nucleus
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Atomic Number and Atomic Weight
number of protons in the nucleus of one atom each element has a unique atomic number equals the number of electrons in the atom Atomic Weight the number of protons plus the number of neutrons in one atom electrons do not contribute to the weight of the atom
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Isotopes Isotopes atoms with the same atomic numbers but with different atomic weights atoms with the same number of protons and electrons but a different number of neutrons oxygen often forms isotopes (O16, O17, O18) unstable isotopes are radioactive; they emit energy or atomic fragments
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Molecules and Compounds
Molecule – particle formed when two or more atoms chemically combine Compound – particle formed when two or more atoms of different elements chemically combine Molecular formulas – depict the elements present and the number of each atom present in the molecule H C6H12O H2O
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Bonding of Atoms bonds form when atoms combine with other atoms
electrons of an atom occupy regions of space called electron shells which circle the nucleus each shell can hold a limited number of electrons for atoms with atomic numbers of 18 or less, the following rules apply: the first shell can hold up to 2 electrons the second shell can hold up to 8 electrons the third shell can hold up to 8 electrons
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Bonding of Atoms lower shells are filled first
if the outermost shell is full, the atom is stable
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Ions Ion an atom that gains or loses electrons to become stable an electrically charged atom Cation a positively charged ion formed when an atom loses electrons Anion a negatively charged ion formed when an atom gains electrons
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Ionic Bond Ionic Bond an attraction between a cation and an anion
formed when electrons are transferred from one atom to another atom
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Covalent Bond Formed when atoms share electrons
Hydrogen atoms form single bonds Oxygen atoms form two bonds Nitrogen atoms form three bonds Carbon atoms form four bonds H ― H O = O N ≡ N O = C = O
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Structural Formula Structural formulas show how atoms bond and are arranged in various molecules
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Polar Molecules Polar Molecule
molecule with a slightly negative end and a slightly positive end results when electrons are not shared equally in covalent bonds water is an important polar molecule
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Hydrogen Bonds Hydrogen Bond
a weak attraction between the positive end of one polar molecule and the negative end of another polar molecule formed between water molecules important for protein and nucleic acid structure
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Chemical Reactions Chemical reactions occur when chemical bonds form or break among atoms, ions, or molecules Reactants are the starting materials of the reaction- the atoms, ions, or molecules Products are substances formed at the end of the chemical reaction NaCl ’ Na+ + Cl- Reactant Products
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Types of Chemical Reactions
Synthesis Reaction – more complex chemical structure is formed A + B ’ AB Decomposition Reaction – chemical bonds are broken to form a simpler chemical structure AB ’ A + B Exchange Reaction – chemical bonds are broken and new bonds are formed AB + CD ’ AD + CB Reversible Reaction – the products can change back to the reactants A + B n AB
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Acids, Bases, and Salts Electrolytes – substances that release ions in water NaCl Na+ + Cl- Acids – electrolytes that dissociate to release hydrogen ions in water HCl H+ + Cl- Bases – substances that release ions that can combine with hydrogen ions NaOH Na+ + OH- Salts – electrolytes formed by the reaction between an acid and a base HCl + NaOH H2O + NaCl
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Acid and Base Concentrations
pH scale - indicates the concentration of hydrogen ions in solution Neutral – pH 7; indicates equal concentrations of H+ and OH- Acidic – pH less than 7; indicates a greater concentration of H+ Basic or alkaline – pH greater than 7; indicates a greater concentration of OH-
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Organic Versus Inorganic
Organic molecules contain C and H usually larger than inorganic molecules dissolve in water and organic liquids carbohydrates, proteins, lipids, and nucleic acids Inorganic molecules generally do not contain C usually smaller than organic molecules usually dissociate in water, forming ions water, oxygen, carbon dioxide, and inorganic salts
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Inorganic Substances Water most abundant compound in living material
two-thirds of the weight of an adult human major component of all body fluids medium for most metabolic reactions important role in transporting chemicals in the body absorbs and transports heat Oxygen (O2) used by organelles to release energy from nutrients in order to drive cell’s metabolic activities necessary for survival
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Inorganic Substances Carbon dioxide (CO2)
waste product released during metabolic reactions must be removed from the body Inorganic salts abundant in body fluids sources of necessary ions (Na+, Cl-, K+, Ca2+, etc.) play important roles in metabolism
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Organic Substances Carbohydrates
provide energy to cells supply materials to build cell structures water-soluble contain C, H, and O ratio of H to O close to 2:1 (C6H12O6) monosaccharides – glucose, fructose disaccharides – sucrose, lactose polysaccharides – glycogen, cellulose
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Organic Substances Carbohydrates
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Organic Substances Lipids
soluble in organic solvents; insoluble in water fats (triglycerides) used primarily for energy; most common lipid in the body contain C, H, and O but less O than carbohydrates (C57H110O6) building blocks are 1 glycerol and 3 fatty acids per molecule saturated and unsaturated
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Organic Substances Lipids
phospholipids building blocks are 1 glycerol, 2 fatty acids, and 1 phosphate per molecule hydrophilic and hydrophobic major component of cell membranes 2-25
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Organic Substances Lipids
steroids four connected rings of carbon widely distributed in the body, various functions component of cell membrane used to synthesize hormones cholesterol
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Organic Substances Proteins
structural material energy source hormones receptors enzymes antibodies amino acids held together with peptide bonds building blocks are amino acids 2-27
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Organic Substances Proteins
Four Levels of Structure
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Organic Substances Nucleic Acids
carry genes encode amino acid sequences of proteins building blocks are nucleotides DNA (deoxyribonucleic acid) – double polynucleotide RNA (ribonucleic acid) – single polynucleotide
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Organic Substances Nucleic Acids
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PowerPoint Lecture Outlines to accompany
Hole’s Human Anatomy and Physiology Eleventh Edition Shier w Butler w Lewis Chapter 3 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
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Chapter 3 Cells vary in size possess distinctive shapes
measured in micrometers
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Cell Membrane outer limit of cell
controls what moves in and out of cell selectively permeable phospholipid bilayer water-soluble “heads” form surfaces water-insoluble “tails” form interior permeable to lipid-soluble substances cholesterol stabilizes the membrane proteins receptors pores, channels, carriers enzymes CAMS self-markers
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Cell Membrane
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Intercellular Junctions
Tight junctions close space between cells located among cells that form linings Desmosomes form “spot welds” between cells located among outer skin cells Gap junctions tubular channels between cells located in cardiac muscle cells
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Cell Adhesion Molecules
guide cells on the move selectin – allows white blood cells to “anchor” integrin – guides white blood cells through capillary walls important for growth of embryonic tissue important for growth of nerve cells
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Cytoplasmic Organelles
Endoplasmic Reticulum connected, membrane-bound sacs, canals, and vesicles transport system rough ER studded with ribosomes protein synthesis smooth ER lipid synthesis added to proteins arriving from rough ER break down of drugs Ribosomes free floating or connected to ER provide structural support
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Cytoplasmic Organelles
Golgi apparatus stack of flattened, membranous sacs modifies, packages and delivers proteins Vesicles membranous sacs store substances Mitochondria membranous sacs with inner partitions generate energy
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Cytoplasmic Organelles
Lysosomes enzyme-containing sacs digest worn out cell parts or unwanted substances Centrosome two rod-like centrioles used to produce cilia and flagella distributes chromosomes during cell division Peroxisomes enzyme-containing sacs break down organic molecules
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Cytoplasmic Organelles
Cilia short hair-like projections propel substances on cell surface Flagellum long tail-like projection provides motility to sperm
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Cytoplasmic Organelles
Microfilaments and microtubules thin rods and tubules support cytoplasm allows for movement of organelles Inclusions temporary nutrients and pigments
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Cell Nucleus control center of cell nuclear envelope nucleolus
porous double membrane separates nucleoplasm from cytoplasm nucleolus dense collection of RNA and proteins site of ribosome production chromatin fibers of DNA and proteins stores information for synthesis of proteins
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Movements Into and Out of the Cell
Passive (Physical) Processes require no cellular energy simple diffusion facilitated diffusion osmosis filtration Active (Physiological) Processes require cellular energy active transport endocytosis exocytosis transcytosis
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Simple Diffusion movement of substances from regions of higher concentration to regions of lower concentration oxygen, carbon dioxide and lipid-soluble substances
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Facilitated Diffusion
diffusion across a membrane with the help of a channel or carrier molecule glucose and amino acids
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Osmosis movement of water through a selectively permeable membrane from regions of higher concentration to regions of lower concentration water moves toward a higher concentration of solutes
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Osmosis Osmotic Pressure – ability of osmosis to generate enough pressure to move a volume of water Osmotic pressure increases as the concentration of nonpermeable solutes increases hypertonic – higher osmotic pressure hypotonic – lower osmotic pressure isotonic – same osmotic pressure
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Filtration smaller molecules are forced through porous membranes
hydrostatic pressure important in the body molecules leaving blood capillaries
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Active Transport carrier molecules transport substances across a membrane from regions of lower concentration to regions of higher concentration sugars, amino acids, sodium ions, potassium ions, etc.
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Endocytosis cell engulfs a substance by forming a vesicle around the substance three types pinocytosis – substance is mostly water phagocytosis – substance is a solid receptor-mediated endocytosis – requires the substance to bind to a membrane-bound receptor
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Endocytosis
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Exocytosis reverse of endocytosis
substances in a vesicle fuse with cell membrane contents released outside the cell release of neurotransmitters from nerve cells
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Transcytosis endocytosis followed by exocytosis
transports a substance rapidly through a cell HIV crossing a cell layer
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The Cell Cycle series of changes a cell undergoes from the time it forms until the time it divides stages interphase mitosis cytoplasmic division
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Interphase very active period cell grows
cell maintains routine functions cell replicates genetic material to prepare for nuclear division cell synthesizes new organelles to prepare for cytoplasmic division phases G phases – cell grows and synthesizes structures other than DNA S phase – cell replicates DNA
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Mitosis produces two daughter cells from an original somatic cell
nucleus divides – karyokinesis cytoplasm divides – cytokinesis stages prophase – chromosomes form; nuclear envelope disappears metaphase – chromosomes align midway between centrioles anaphase – chromosomes separate and move to centrioles telophase – chromatin forms; nuclear envelope forms
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Mitosis
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Cytoplasmic Division also known as cytokinesis begins during anaphase
continues through telophase contractile ring pinches cytoplasm in half
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Control of Cell Division
cell division capacities vary greatly among cell types skin and blood cells divide often and continually neuron cells divide a specific number of times then cease chromosome tips (telomeres) that shorten with each mitosis provide a mitotic clock cells divide to provide a more favorable surface area to volume relationship growth factors and hormones stimulate cell division hormones stimulate mitosis of smooth muscle cells in uterus epidermal growth factor stimulates growth of new skin contact (density dependent) inhibition tumors are the consequence of a loss of cell cycle control
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Tumors Two types of tumors benign – usually remains localized
malignant – invasive and can metastasize; cancerous Two major types of genes cause cancer oncogenes – activate other genes that increase cell division tumor suppressor genes – normally regulate mitosis; if inactivated they are unable to regulate mitosis cells are now known as “immortal”
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Stem and Progenitor Cells
Stem cell can divide to form two new stem cells self-renewal can divide to form a stem cell and a progenitor cell totipotent – can give rise to every cell type pluripotent – can give rise to a restricted number of cell types Progenitor cell committed cell can divide to become any of a restricted number of cells pluripotent
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Stem and Progenitor Cells
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