Get Ready for A & P! Biological Hierarchy of Organization, Homeostasis & Overview of Organ Systems

What Is Energy? Capacity to do workCapacity to do work Forms of energyForms of energy –Potential energy –Kinetic energy –Chemical energy

First Law of Thermodynamics The total amount of energy in the universe remains constantThe total amount of energy in the universe remains constant Energy can undergo conversions from one form to another, but it cannot be created or destroyedEnergy can undergo conversions from one form to another, but it cannot be created or destroyed

What Can Cells Do with Energy? Energy inputs become coupled to energy-requiring processesEnergy inputs become coupled to energy-requiring processes Cells use energy for:Cells use energy for: –Chemical work –Mechanical work –Electrochemical work

Second Law of Thermodynamics No energy conversion is ever 100 percent efficientNo energy conversion is ever 100 percent efficient The total amount of energy is flowing from high-energy forms to forms lower in energyThe total amount of energy is flowing from high-energy forms to forms lower in energy

Enzyme Structure and Function Enzymes are catalytic protein moleculesEnzymes are catalytic protein molecules They speed the rate at which reactions approach equilibriumThey speed the rate at which reactions approach equilibrium

Four Features of Enzymes 1) Enzymes do not make anything happen that could not happen on its own. They just make it happen much faster. 2) Reactions do not alter or use up enzyme molecules.

Four Features of Enzymes 3) The same enzyme usually works for both the forward and reverse reactions. 4) Each type of enzyme recognizes and binds to only certain substrates.

Activation Energy For a reaction to occur, an energy barrier must be surmountedFor a reaction to occur, an energy barrier must be surmounted Enzymes make the energy barrier smallerEnzymes make the energy barrier smaller activation energy without enzyme activation energy with enzyme energy released by the reaction products starting substance

Some Factors Influencing Enzyme Activity TemperaturepH Salt concentration Coenzymes and cofactors

Metabolic Pathways Defined as enzyme- mediated sequences of reactions in cellsDefined as enzyme- mediated sequences of reactions in cells –Biosynthetic (anabolic) – ex: photosynthesis –Degradative (catabolic) – ex: aerobic respiration

Main Types of Energy-Releasing Pathways Aerobic pathways Evolved laterEvolved later Require oxygenRequire oxygen Start with glycolysis in cytoplasm & completed in mitochondriaStart with glycolysis in cytoplasm & completed in mitochondria More efficient – less energy lost as heatMore efficient – less energy lost as heat Anaerobic pathways Evolved firstEvolved first Don’t require oxygenDon’t require oxygen Start with glycolysis in cytoplasm & completed in cytoplasmStart with glycolysis in cytoplasm & completed in cytoplasm Very inefficient – most of energy lost as heatVery inefficient – most of energy lost as heat

Summary Equation for Aerobic Respiration C 6 H O 2 6CO 2 + 6H 2 0 glucose oxygen carbon water glucose oxygen carbon water dioxide dioxide

Summary Equation for Photosynthesis C 6 H O 2 6CO 2 + 6H 2 0 glucose oxygen carbon water glucose oxygen carbon water dioxide dioxide

Processes Are Linked sunlight energy water + carbon dioxide PHOTOSYNTHESIS AEROBIC RESPIRATION sugar molecules oxygen

686 kcal of energy are released686 kcal of energy are released 7.5 kcal are conserved in each ATP7.5 kcal are conserved in each ATP When 36 ATP form, 270 kcal (36 X 7.5) are captured in ATPWhen 36 ATP form, 270 kcal (36 X 7.5) are captured in ATP Efficiency is 270 / 686 X 100 = 39 percentEfficiency is 270 / 686 X 100 = 39 percent Most of the energy is lost as heat, but still less than with anaerobic processesMost of the energy is lost as heat, but still less than with anaerobic processes Efficiency of Aerobic Respiration

Body Organization Tissue –Group of cells performing same task Organ –Two or more tissues performing same task Organ system –Two or more organs performing same task

Tissues Groups of cells and intercellular substances that interact in one or more tasks Example: muscle tissue

Organs Group of tissues organized to perform a task or tasks Example: Heart is an organ that pumps blood through body Heart consists of muscle tissue, nervous tissue, connective tissue, and epithelial tissue

Organ Systems Groups of organs that interact physically and/or chemically to perform a common task Example: Circulatory system includes heart, arteries, and other vessels that transport blood through the body

Homeostasis Stable operating conditions in the internal environment Brought about by coordinated activities of cells, tissues, organs, and organ systems

22 Homeostatic Mechanisms

4 Types of Tissues Epithelial tissues Connective tissues Muscle tissues Nervous tissues

Epithelial Tissues Line body surfaces, cavities, ducts, and tubes One free surface faces a body fluid or the environment simple squamous epithelium basement membrane connective tissue

simple epithelium basement membrane connective tissue free surface of epithelium Epithelium

Structure of an epithelium Epithelial

Connective Tissues Most abundant tissues in the body Fibroblasts secrete –polysaccharide “ground substance” that surrounds and supports cells –fibers of collagen and/or elastin

Soft Connective Tissues Loose connective tissue Dense, irregular connective tissue Dense, regular connective tissue

Soft connective tissue Soft Connective Tissues

Specialized Connective Tissues Cartilage Bone tissue Adipose tissue Blood

Specialized connective tissue Specialized Connective Tissues

red blood cell white blood cell platelet Fig. 20-3g, p.342 cells and platelets of blood

Muscle Tissue Cells contract when stimulated Moves body and specific body parts 3 types –Skeletal –Cardiac –Smooth

Skeletal Muscle Attaches to and moves bones Long, cylindrical cells Striated cells Voluntary control nucleus

Smooth Muscle Located in soft internal organs and blood vessels Cells taper at ends Cells not striated Not under voluntary control where abutting cells meet

Cardiac Muscle Present only in heart Cells are branching –ends of cells joined by communication junctions Cells striated Not under voluntary control cell nucleus

Muscle tissues Muscle Tissues

Nervous Tissue Detects stimuli, integrates information, and relays commands for response Consists of excitable neurons and supporting neuroglial cells

Neurons Excitable cells Stimulus sends electrical impulse along plasma membrane Transmits information to other neurons, muscles or glands

Neuroglia Neuroglial cells make up more than half of nervous tissue Protect and support neurons

11 Major Organ Systems Integumentary Nervous Muscular Skeletal Circulatory Endocrine

Nervous System Muscular System Skeletal System Circulatory System Endocrine System Fig. 20-6, p.344a1 Integumentary System 11 Major Organ Systems

Lymphatic Respiratory Digestive Urinary Reproductive

Lymphatic System Respiratory System Digestive System Urinary System Reproductive System Fig. 20-6a2, p Major Organ Systems

Human organ systems Major Organ Systems