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Biological Hierarchy of Organization, Homeostasis & Overview of Organ Systems

What Is Energy?What Is Energy?

• Capacity to do workCapacity to do work

• Forms of energyForms of energy– Potential energyPotential energy– Kinetic energyKinetic energy– Chemical energyChemical energy

First Law of ThermodynamicsFirst Law of Thermodynamics

• The total amount of energy in the The total amount of energy in the universe remains constantuniverse remains constant

• Energy can undergo conversions from Energy can undergo conversions from one form to another, but it cannot be one form to another, but it cannot be created or destroyedcreated or destroyed

What Can Cells Do What Can Cells Do with Energy?with Energy?

• Energy inputs become coupled to Energy inputs become coupled to

energy-requiring processesenergy-requiring processes

• Cells use energy for:Cells use energy for:– Chemical workChemical work

– Mechanical workMechanical work

– Electrochemical workElectrochemical work

Second Law of ThermodynamicsSecond Law of Thermodynamics

• No energy conversion is ever 100 No energy conversion is ever 100

percent efficientpercent efficient

• The total amount of energy is flowing The total amount of energy is flowing

from high-energy forms to forms from high-energy forms to forms

lower in energylower in energy

Enzyme Structure Enzyme Structure and Functionand Function

• Enzymes are catalytic protein moleculesEnzymes are catalytic protein molecules

• They speed the rate at which reactions approach They speed the rate at which reactions approach equilibriumequilibrium

Four Features of EnzymesFour Features of Enzymes1) Enzymes do not make anything 1) Enzymes do not make anything

happen that could not happen on its happen that could not happen on its own. They just make it happen much own. They just make it happen much faster.faster.

2) Reactions do not alter or use up 2) Reactions do not alter or use up enzyme molecules.enzyme molecules.

Four Features of EnzymesFour Features of Enzymes

3) The same enzyme usually works for 3) The same enzyme usually works for

both the forward and reverse both the forward and reverse reactions.reactions.

4) Each type of enzyme recognizes and 4) Each type of enzyme recognizes and binds to only certain substrates.binds to only certain substrates.

Activation EnergyActivation Energy

• For a reaction to For a reaction to occur, an energy occur, an energy barrier must be barrier must be surmountedsurmounted

• Enzymes make the Enzymes make the energy barrier energy barrier smallersmaller

activation energywithout enzyme

activation energywith enzyme

energyreleased

by thereaction

products

starting substance

Some Factors Influencing Some Factors Influencing Enzyme ActivityEnzyme Activity

Temperature Temperature

pHpH

Salt concentrationSalt concentration

Coenzymes and cofactorsCoenzymes and cofactors

Metabolic PathwaysMetabolic Pathways

• Defined as enzyme-Defined as enzyme-mediated sequences of mediated sequences of reactions in cellsreactions in cells– Biosynthetic (anabolic) – Biosynthetic (anabolic) –

ex: photosynthesisex: photosynthesis– Degradative (catabolic) – Degradative (catabolic) –

ex: aerobic ex: aerobic respirationrespiration

ENERGY IN ENERGY IN

organiccompounds,

oxygen

photosynthesis

aerobic respiration

ENERGY OUT

carbondioxide,

water

Main Types of Main Types of Energy-Releasing Pathways Energy-Releasing Pathways

Aerobic pathwaysAerobic pathways

• Evolved laterEvolved later

• Require oxygenRequire oxygen

• Start with glycolysis in Start with glycolysis in cytoplasm & completed cytoplasm & completed in mitochondriain mitochondria

• More efficient – less More efficient – less energy lost as heatenergy lost as heat

Anaerobic pathwaysAnaerobic pathways

• Evolved firstEvolved first

• Don’t require oxygenDon’t require oxygen

• Start with glycolysis in Start with glycolysis in cytoplasm & completed in cytoplasm & completed in cytoplasmcytoplasm

• Very inefficient – most of Very inefficient – most of energy lost as heatenergy lost as heat

Summary Equation for Aerobic Summary Equation for Aerobic RespirationRespiration

CC66HH12120066 + 6O + 6O22 6CO6CO22 + 6H + 6H2200

glucose oxygen glucose oxygen carbon water carbon water

dioxidedioxide

Summary Equation for Summary Equation for PhotosynthesisPhotosynthesis

CC66HH12120066 + 6O + 6O22 6CO6CO22 + 6H + 6H2200

glucose oxygen glucose oxygen carbon water carbon water

dioxidedioxide

Processes Are Linked Processes Are Linked

sunlight energy

water+

carbondioxide

PHOTOSYNTHESIS

AEROBICRESPIRATION

sugarmolecules oxygen

• 686 kcal of energy are released 686 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 When 36 ATP form, 270 kcal (36 X 7.5) are

captured in ATPcaptured in ATP

• Efficiency is 270 / 686 X 100 = 39 percent Efficiency is 270 / 686 X 100 = 39 percent

• Most of the energy is lost as heat, but still Most of the energy is lost as heat, but still

less than with anaerobic processesless than with anaerobic processes

Efficiency ofEfficiency of Aerobic Respiration 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

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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 simplesquamousepithelium

basementmembrane

connective tissue

simple epithelium

basement membrane

connective tissue

free surface of epithelium

Epithelium

Structure of an epitheliumStructure of an epithelium

EpithelialEpithelial

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 tissueSoft connective tissue

Soft Connective TissuesSoft Connective Tissues

Specialized Connective Tissues• Cartilage

• Bone tissue

• Adipose tissue

• Blood

Specialized connective tissueSpecialized connective tissue

Specialized Specialized Connective TissuesConnective 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 tissuesMuscle tissues

Muscle TissuesMuscle 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

11 Major Organ Systems

• Lymphatic

• Respiratory

• Digestive

• Urinary

• Reproductive

Lymphatic System

Respiratory System

Digestive System

Urinary System

Reproductive System

Fig. 20-6a2, p.344

11 Major Organ Systems

Human organ systemsHuman organ systems

Major Organ SystemsMajor Organ Systems