Chapter 20Chapter 20

UNIFYING CONCEPTS OFUNIFYING CONCEPTS OF

ANIMAL STRUCTURE AND ANIMAL STRUCTURE AND

FUNCTIONFUNCTION

I. Life is based on many structural levelsI. Life is based on many structural levels

Levels of animal structure:Levels of animal structure: Atoms and molecules Atoms and molecules CellsCells TissuesTissues OrgansOrgans Organ systemsOrgan systems OrganismOrganism: May consist of a single cell or a : May consist of a single cell or a

complex multicellular organism.complex multicellular organism.

Levels of Structural Organization in an Animal

TISSUES:TISSUES: Most animal cells are organized into tissues.Most animal cells are organized into tissues.

Cooperative unit of very similar cells that perform Cooperative unit of very similar cells that perform

a specific function. a specific function.

Tissue comes from Latin word meaning “weave”.Tissue comes from Latin word meaning “weave”.

Cells of tissues may be held together by:Cells of tissues may be held together by: FibersFibers

Glue-like substanceGlue-like substance

Plasma membrane structuresPlasma membrane structures

Tissue structure is related to its function.Tissue structure is related to its function.

TISSUES:TISSUES:There are four main types of animal There are four main types of animal tissue:tissue:1. Epithelial1. Epithelial

2. Connective2. Connective

3. Muscle3. Muscle

4. Nervous4. Nervous

1. Epithelial Tissue1. Epithelial Tissue Cells are tightly fitted together in continuous Cells are tightly fitted together in continuous

layerslayers or or sheetssheets.. Cover outside of body (skin), line organs and Cover outside of body (skin), line organs and

internal body cavities (Mucous membranes of internal body cavities (Mucous membranes of digestive, respiratory, and reproductive systems).digestive, respiratory, and reproductive systems).

Tight packaging allows tissue to act as a Tight packaging allows tissue to act as a barrierbarrier to protect against mechanical injury, infection, to protect against mechanical injury, infection, and fluid loss.and fluid loss.

Two surfaces:Two surfaces: Free surfaceFree surface: Exposed to air or fluid.: Exposed to air or fluid. Bottom surfaceBottom surface:: Attached to underlying tissues by a Attached to underlying tissues by a

basement membranebasement membrane, a dense layer of protein and , a dense layer of protein and polysaccharides.polysaccharides.

1. Epithelial Tissue1. Epithelial TissueCan be classified based on two criteria:Can be classified based on two criteria:

A. Number of layers:A. Number of layers: SimpleSimple: : One layer.One layer. StratifiedStratified: Several layers: Several layers

B. Shape of cells:B. Shape of cells: SquamousSquamous: Flat cells.: Flat cells. CuboidalCuboidal: Cube shaped cells: Cube shaped cells Columnar:Columnar: Column shaped cells Column shaped cells

ExampleExample: : Simple squamous epitheliumSimple squamous epithelium Stratified columnar epitheliumStratified columnar epithelium

Epithelial Tissue Covers and Lines the Body and its Parts

A. Simple squamous(Lung air sacs)

D. Statified squamous(Lining esophagus)

B. Simple cuboidal(Kidney tubes)

C. Statified columnar(Lining intestine)

1. Epithelial Tissue1. Epithelial TissueSome epithelial tissues, such as mucous membranes, Some epithelial tissues, such as mucous membranes,

absorb and secrete chemical solutions. absorb and secrete chemical solutions. Mucous membranes:Mucous membranes:

Digestive tract epithelium (mucous membranes) Digestive tract epithelium (mucous membranes) secretes mucus and digestive enzymes.secretes mucus and digestive enzymes.

Respiratory tract epithelium secretes mucous that Respiratory tract epithelium secretes mucous that helps trap dust particles before they reach the lungs.helps trap dust particles before they reach the lungs.

2. Connective Tissue2. Connective Tissue Relatively few cells surrounded by large amounts Relatively few cells surrounded by large amounts

of nonliving material (of nonliving material (matrixmatrix).). Cells secrete the matrix, which can be solid, Cells secrete the matrix, which can be solid,

liquid, or gelatinous.liquid, or gelatinous. Diverse functions. Mainly bind, support, and Diverse functions. Mainly bind, support, and

connect other tissues.connect other tissues. Six types of connective tissue in humans:Six types of connective tissue in humans:

1. 1. Loose Connective TissueLoose Connective Tissue: Most widespread connective : Most widespread connective tissue in vertebrates. Loose matrix with fibers, tissue in vertebrates. Loose matrix with fibers, packingpacking material. Attaches skin to muscles, binds and material. Attaches skin to muscles, binds and holds tissues and organs in place.holds tissues and organs in place.

2. 2. Adipose (fat):Adipose (fat): Pads and insulates body. Energy Pads and insulates body. Energy storage.storage.

Connective Tissue Binds and Provides Support

A. Loose Connective Tissue

B. Adipose Tissue

C. Blood

D. Fibrous Connective Tissue

E. Cartilage

F. Bone

Types of connective tissue in humans (Continued):Types of connective tissue in humans (Continued):

C. C. BloodBlood: Fluid matrix (: Fluid matrix (plasmaplasma) has water, salts, and ) has water, salts, and proteins. Red and white blood cells.proteins. Red and white blood cells.

D. D. Fibrous Connective TissueFibrous Connective Tissue: Matrix of densely packed : Matrix of densely packed collagen fibers. Strong and nonelastic. Found in:collagen fibers. Strong and nonelastic. Found in:

• Tendons:Tendons: Attach muscles to bones. Attach muscles to bones.

• Ligaments:Ligaments: Attach bone to bone. Attach bone to bone.

E. E. CartilageCartilage: Rubbery matrix with collagen fibers. : Rubbery matrix with collagen fibers. Found on end of bones, nose, ears, and between Found on end of bones, nose, ears, and between vertebra.vertebra.

F. F. Bone:Bone: Supports the body of most vertebrates. Solid Supports the body of most vertebrates. Solid matrix of collagen fibers and calcium, phosphate, and matrix of collagen fibers and calcium, phosphate, and magnesium salts. Bone is harder than cartilage, but not magnesium salts. Bone is harder than cartilage, but not brittle because of collagen.brittle because of collagen.

3. Muscle Tissue3. Muscle Tissue Most abundant type of tissue in most animals. Most abundant type of tissue in most animals.

Accounts for two-thirds (2/3) of human weight.Accounts for two-thirds (2/3) of human weight. Specialized for Specialized for contractioncontraction. Made up of long cells . Made up of long cells

that contract when stimulated by that contract when stimulated by nerve impulsesnerve impulses.. Muscle cells have many Muscle cells have many microfilamentsmicrofilaments made up made up

of of actinactin and and myosinmyosin.. Muscle contraction accounts for much of energy Muscle contraction accounts for much of energy

consuming work in animals.consuming work in animals. Adults have a Adults have a fixed number of muscle cellsfixed number of muscle cells. .

Weight lifting doesn’t increase number of muscle Weight lifting doesn’t increase number of muscle cells, only their size.cells, only their size.

3. Muscle Tissue3. Muscle TissueThere are three types of muscle tissue:There are three types of muscle tissue:

A. A. Skeletal (striated) muscle Skeletal (striated) muscle : Attached to bones by : Attached to bones by

tendons. tendons.

Responsible for Responsible for voluntaryvoluntary movements. movements.

B. B. Cardiac muscleCardiac muscle: Forms contractile tissue of heart. : Forms contractile tissue of heart.

Not under voluntary controlNot under voluntary control..

C. C. Smooth muscle:Smooth muscle: Found in walls of digestive tract, Found in walls of digestive tract,

bladder, arteries, uterus, and many internal organs. bladder, arteries, uterus, and many internal organs.

Responsible for peristalsis and labor contractions. Responsible for peristalsis and labor contractions.

Contract more slowly than skeletal muscle, but can Contract more slowly than skeletal muscle, but can

remain contracted longer. remain contracted longer.

Not under voluntary controlNot under voluntary control..

A. Skeletal muscle

B. Cardiac muscle

C. Smooth muscle

Three Types of Muscle

4. Nervous Tissue4. Nervous Tissue Senses stimuli and transmits signals from one Senses stimuli and transmits signals from one

part of the animal to another.part of the animal to another. Controls the activity of muscles and glands, and Controls the activity of muscles and glands, and

allows the animal to allows the animal to respondrespond to its to its environmentenvironment.. NeuronNeuron: Nerve cell. Structural and functional : Nerve cell. Structural and functional

unit of nervous tissue. Consists of:unit of nervous tissue. Consists of: Cell body Cell body : Contains cell’s nucleus.: Contains cell’s nucleus. DendriteDendrite: Extension that conveys signals towards the : Extension that conveys signals towards the

cell body. cell body. Axon:Axon: Extension that transmits signals away from the Extension that transmits signals away from the

cell body. cell body.

Supporting cellsSupporting cells: : Nourish, protect, and insulate Nourish, protect, and insulate neurons.neurons.

Nervous Tissue Forms a Communication Network

Organs are made up of different tissuesOrgans are made up of different tissues Organ: Organ: Several tissues that act as a unit Several tissues that act as a unit

and together perform one or more and together perform one or more biological functions.biological functions. Perform functions that component tissues can’t Perform functions that component tissues can’t

carry out alone.carry out alone.

Example: The heart is an organ made up of:Example: The heart is an organ made up of:• Muscle TissueMuscle Tissue: Contraction: Contraction

• Epithelial TissueEpithelial Tissue: Lines heart chambers to prevent : Lines heart chambers to prevent leakage and provide a smooth surface.leakage and provide a smooth surface.

• Connective TissueConnective Tissue: Makes heart elastic and : Makes heart elastic and strengthens its walls and valves.strengthens its walls and valves.

• Nervous TissueNervous Tissue: Direct heart contractions.: Direct heart contractions.

Organs are Made of Several Different Tissues

Animals Regulate their Internal Animals Regulate their Internal EnvironmentEnvironment

Homeostasis: Homeostasis: “Steady state”.“Steady state”. Internal environment of animal remains fairly Internal environment of animal remains fairly

constant despite changes in the external constant despite changes in the external environment.environment.

Control systems maintain internal conditions Control systems maintain internal conditions within a range in which life’s metabolic within a range in which life’s metabolic activities can occur.activities can occur.

Homeostasis is a Homeostasis is a dynamic statedynamic state resulting from resulting from changes in the outside environment and changes in the outside environment and internal control mechanisms that oppose such internal control mechanisms that oppose such changes.changes.

Homeostatic Mechanisms Counteract Changes in External Conditions

Animals Regulate their Internal Animals Regulate their Internal EnvironmentEnvironment

Homeostasis: Homeostasis: Maintained by Maintained by negative feedback mechanismsnegative feedback mechanisms.. A change in one condition (e.g.: low body A change in one condition (e.g.: low body

temperature), results is a response that temperature), results is a response that counteractscounteracts that change (e.g.: shivering, etc.). that change (e.g.: shivering, etc.).

Internal conditions regulated by negative Internal conditions regulated by negative feedback:feedback:

• Body temperature (Normal range: 97 - 100Body temperature (Normal range: 97 - 100ooF)F)

• Salt concentrationSalt concentration

• pHpH

• Blood levels of sugar, calcium, oxygen, etc.Blood levels of sugar, calcium, oxygen, etc.

Negative Feedback as Homeostatic Mechanism

Body Temperature is Regulated by Homeostasis

Major Organ Systems in MammalsMajor Organ Systems in Mammals Digestive systemDigestive system Respiratory systemRespiratory system Circulatory systemCirculatory system

CardiovascularCardiovascular Lymphatic and Immune systemLymphatic and Immune system

Excretory systemExcretory system Endocrine systemEndocrine system Reproductive systemReproductive system Nervous systemNervous system Muscular systemMuscular system Skeletal systemSkeletal system IntegumentaryIntegumentary

1. Digestive System1. Digestive System

Components: Components: Mouth, salivary glands, throat, Mouth, salivary glands, throat, esophagus, stomach, intestines, liver, gallbladder, esophagus, stomach, intestines, liver, gallbladder, pancreas, rectum, and anus.pancreas, rectum, and anus.

Functions:Functions: Ingest and mechanically break down food.Ingest and mechanically break down food. Digest food: Stomach and small intestine mainly.Digest food: Stomach and small intestine mainly. Absorb nutrients and water.Absorb nutrients and water. Eliminate waste.Eliminate waste.

Homeostatic Roles:Homeostatic Roles: Supplies energy for life’s activities.Supplies energy for life’s activities. Supplies building blocks for macromoleculesSupplies building blocks for macromolecules

Human Digestive System

2. Respiratory System2. Respiratory System

Components: Components: Nose, throat, larynx, trachea, Nose, throat, larynx, trachea, bronchi, and lungs.bronchi, and lungs.

Functions:Functions: Exchange gases with the environment:Exchange gases with the environment:

Supplies blood with oxygen.Supplies blood with oxygen. Disposes of carbon dioxide (waste product from cellular Disposes of carbon dioxide (waste product from cellular

respiration).respiration).

Homeostatic Roles:Homeostatic Roles: Regulates blood pH.Regulates blood pH. Regulates blood oxygen and carbon dioxide levels.Regulates blood oxygen and carbon dioxide levels.

Human Respiratory System

3. Cardiovascular System3. Cardiovascular System

Components: Components: Blood, heart, arteries, veins, and Blood, heart, arteries, veins, and capillaries.capillaries.

Functions:Functions: Exchange gases with the respiratory system.Exchange gases with the respiratory system.

Supplies tissues with oxygen.Supplies tissues with oxygen. Removes carbon dioxide from tissues.Removes carbon dioxide from tissues.

Transports materials (nutrients, hormones, etc.) inside Transports materials (nutrients, hormones, etc.) inside body.body.

Defends against infection.Defends against infection.

Homeostatic Roles:Homeostatic Roles: Provides nutrients and removes waste materials from Provides nutrients and removes waste materials from

tissues.tissues. Regulates body temperature, water and ion balance.Regulates body temperature, water and ion balance.

Human Cardiovascular System

4. Lymphatic and Immune System4. Lymphatic and Immune System

Components: Components: Lymph, lymphatic vessels, bone Lymph, lymphatic vessels, bone marrow, thymus, spleen, and lymph nodes.marrow, thymus, spleen, and lymph nodes.

Functions:Functions: Defends against infection: bacteria, fungi, viruses, etc.Defends against infection: bacteria, fungi, viruses, etc. Destruction of cancer and foreign cells.Destruction of cancer and foreign cells. Synthesis of antibodies and other immune molecules.Synthesis of antibodies and other immune molecules. Synthesis of white blood cells.Synthesis of white blood cells.

Homeostatic Role:Homeostatic Role: Returns fluid and proteins that have leaked from Returns fluid and proteins that have leaked from

blood capillaries into tissues. blood capillaries into tissues. Up to 4 liters of fluid every day.Up to 4 liters of fluid every day. Fluid returned near heart/venae cavae.Fluid returned near heart/venae cavae.

Lymphatic and Immune Systems

5. Excretory (Urinary) System5. Excretory (Urinary) System

Components: Components: Kidneys, bladder, urethra, and Kidneys, bladder, urethra, and associated ducts.associated ducts.

Functions:Functions: Kidneys remove nitrogen containing waste from blood.Kidneys remove nitrogen containing waste from blood. Urine with waste is temporarily stored in bladder.Urine with waste is temporarily stored in bladder. Excretion of urine.Excretion of urine.

Homeostatic Role:Homeostatic Role: Regulates water levels in body.Regulates water levels in body.

Removes excess waterRemoves excess water Helps conserve waterHelps conserve water

Human Excretory System

6. Endocrine System6. Endocrine System

Components: Components: Pituitary, adrenal, thyroid, thymus, Pituitary, adrenal, thyroid, thymus, pancreas, ovaries, testes, and other ductless pancreas, ovaries, testes, and other ductless glands.glands.

Functions:Functions: Produce hormones that regulate:Produce hormones that regulate:

Blood chemistry: Levels of sugars, minerals, etc.Blood chemistry: Levels of sugars, minerals, etc. ReproductionReproduction GrowthGrowth MetabolismMetabolism DigestionDigestion

Homeostatic Role:Homeostatic Role: With nervous system, regulates metabolism and blood With nervous system, regulates metabolism and blood

chemistry.chemistry.

Human Endocrine System

7. Reproductive System7. Reproductive System

Components: Components:

Female: Ovaries, oviduct, uterus, vagina, and Female: Ovaries, oviduct, uterus, vagina, and associated structuresassociated structures

Male: Testes, seminal vesicles, prostate, urethra, Male: Testes, seminal vesicles, prostate, urethra, penis, and associated structures.penis, and associated structures.

Functions:Functions: Only organ system that is Only organ system that is not essentialnot essential for individual for individual

survival.survival. Continuation of species.Continuation of species. Gamete formation (eggs and sperm cells).Gamete formation (eggs and sperm cells).

Homeostatic Role:Homeostatic Role: Maintains secondary sexual characteristics.Maintains secondary sexual characteristics.

Male Reproductive System

Female Reproductive System

Gamete Formation Occurs in Testis

8. Nervous System8. Nervous System

Components: Components: Brain, spinal cord, nerves, sense Brain, spinal cord, nerves, sense organs, and associated structures.organs, and associated structures.

Functions:Functions: Works with endocrine system to coordinate body Works with endocrine system to coordinate body

activities.activities. Integrates and processes information from sense Integrates and processes information from sense

organs.organs. Sends signals (instructions) to muscles and glands.Sends signals (instructions) to muscles and glands. Responds to internal stimuli.Responds to internal stimuli.

Homeostatic Role:Homeostatic Role: Regulates most organ activities along with endocrine Regulates most organ activities along with endocrine

system.system.

Human Nervous System

Nervous System Allows Us to Respond to Our Environment

9. Muscular System9. Muscular System

Components: Components: Skeletal muscles.Skeletal muscles.

Functions:Functions:

Skeletal muscle contraction allows for voluntary Skeletal muscle contraction allows for voluntary movement:movement: Movement and locomotion.Movement and locomotion. Mechanical work: Lifting, pulling, pushing objects.Mechanical work: Lifting, pulling, pushing objects. Communication: Body language and facial expression.Communication: Body language and facial expression.

Homeostatic Role:Homeostatic Role: Allows animals to respond to and control their Allows animals to respond to and control their

environment.environment.

Muscular System: Skeletal Muscle Allows Voluntary Movement

10. Skeletal System10. Skeletal System

Components: Components: Bones, ligaments, and cartilage.Bones, ligaments, and cartilage.

Functions:Functions: Along with muscular system:Along with muscular system:

Movement and locomotion.Movement and locomotion. Mechanical work: Lifting, pulling, pushing objects.Mechanical work: Lifting, pulling, pushing objects.

Body support.Body support. Protection of delicate internal organs (brain, heart, Protection of delicate internal organs (brain, heart,

lungs, etc.)lungs, etc.) Calcium storageCalcium storage

Homeostatic Role:Homeostatic Role: Helps maintain constant blood calcium levels.Helps maintain constant blood calcium levels.

Skeletal System: Protection, Movement, & Support

11. Integumentary System11. Integumentary System

Components: Components: Hair, skin, and nails.Hair, skin, and nails.

Functions:Functions: Protects the body from:Protects the body from:

Infection: Barrier to microbes.Infection: Barrier to microbes. Mechanical injuryMechanical injury Excessive heat or cold: Excessive heat or cold: ThermoregulationThermoregulation Water lossWater loss

Communication: Communication: Receives stimuli from environmentReceives stimuli from environment Gives out subtle signals (blushing, etc.).Gives out subtle signals (blushing, etc.).

Homeostatic Role:Homeostatic Role: Helps maintain constant body temperature.Helps maintain constant body temperature.

Integumentary System: Skin, Nails, & Hair

OOrgan systems must be coordinated for rgan systems must be coordinated for animal to surviveanimal to survive Organ systems interact with one another in Organ systems interact with one another in

order to maintain fairly stable conditions order to maintain fairly stable conditions (homeostasis) that are required for life.(homeostasis) that are required for life.

Example: Interactions between:Example: Interactions between:• RespiratoryRespiratory

• CirculatoryCirculatory

• DigestiveDigestive

Relationships Between Several Major Organ Systems