THE HIERARCHY OF STRUCTURAL ORGANIZATION IN AN ANIMAL Copyright © 2009 Pearson Education, Inc.

THE HIERARCHY OF STRUCTURAL

ORGANIZATION IN AN ANIMAL

Copyright © 2009 Pearson Education, Inc.

20.1 Structure fits function at all levels of organization in the animal body

Anatomy—structure

Physiology—function

Animals consist of a hierarchy of levels or organization


20.2 EVOLUTION CONNECTION: An animal’s form reflects natural selection

Sharks, seals, and penguins have streamlined, tapered bodies


Video: Galápagos Sea Lion

Video: Shark Eating a Seal

Shark

Penguin

Seal

Cellular levelMuscle cell

A


Tissue levelMuscle tissue

A B



Organ levelHeart

A B

C



Organ levelHeart

A B

C

D Organ system levelCirculatory system



Organ levelHeart

Organ system levelCirculatory system

Organism levelMany organ systemsfunctioning together

A B

C

D

E

20.3 Tissues are groups of cells with a common structure and function


Animals have four main categories of tissues

– Epithelial tissue

– Connective tissue

– Muscle tissue

– Nervous tissue

20.4 Epithelial tissue covers the body and lines its organs and cavities

Epithelial cells come in three shapes

– Squamous—like a fried egg

– Cuboidal—as tall as they are wide

– Columnar—taller than they are wide


Apical surface ofepithelium

Cellnuclei

Underlyingtissue

Basallamina

Simple squamous epithelium(air sacs of the lung)

Simple cuboidal epithelium(kidney)

Simple columnar epithelium(intestine)

Stratified squamousepithelium(esophagus)

Pseudostratifiedciliated columnarepithelium(respiratory tract)

A

B

C

D

E

20.5 Connective tissue binds and supports other tissues

Connective tissue can be grouped into six major types

The tissue consists of a matrix which can be hard, semi soft or fluid in which are embedded cells.


Fatdroplets

Adiposetissue

Whitebloodcells

Redbloodcell

Blood

Plasma

Loose connectivetissue (underthe skin)

Elasticfibers

Collagenfiber

CellFibrous connectivetissue (forminga tendon)

Collagenfibers

Cellnucleus

Cartilage(at the end of a bone)

Matrix

Cartilage-formingcells

Centralcanal

Matrix

Bone-formingcellsBone

B

AF

E

D

C

20.6 Muscle tissue functions in movement

Skeletal muscle causes voluntary movements

Cardiac muscle pumps blood

Smooth muscle moves walls of internal organs, such as the intestines


Unit ofmusclecontraction Muscle

fiber

Nucleus

Nucleus

Musclefiber

Junction betweentwo cells

NucleusMuscle fiber

Cardiac muscle

Smooth muscle

Skeletal muscle

C

B

A

20.7 Nervous tissue forms a communication network

Neurons carry signals by conducting electrical impulses

Supporting cells insulate axons and nourish neurons


Cell body

Nucleus

20.8 Organs are made up of tissues

Each tissue performs specific functions

The heart has epithelial, connective, and nervous tissues

– Epithelia line the heart chambers

– Connective tissues make the heart elastic

– Neurons regulate contractions


Small intestine

Lumen

Epithelial tissueConnective tissue

Smooth muscletissue (2 layers)

Connective tissue

Epithelial tissue(columnar epithelium)

Lumen

Artificial skin

Used to heal burns

20.9 CONNECTION: Bioengineers are learning to produce tissues and organs for transplants


20.11 CONNECTION: New imaging technology reveals the inner body

New technologies show body organs without surgery

X-rays help to see bones and teeth


Magnetic resonance microscopy (MRM)

– Provides three-dimensional images of very small structures



Positron-emission tomography (PET)

– Helps identify metabolic processes at specific body locations



20.10 Organ systems work together to perform life’s functions

An organ system usually consists of many organs

Each organ system has one or more functions


Endocrine system controls body functions

Skeletal and muscular systems support and move the body

Circulatory system transports the food and oxygen

Respiratory system absorbs oxygen and releases carbon dioxide

Integumentary system covers and protects the body



Circulatorysystem

Heart

Bloodvessels

Respiratory systemNasal cavityLarynx

TracheaBronchusLung

Muscularsystem

Integumentarysystem

Hair

Nails

Skin

Skeletalmuscles

Cartilage

Bone

Skeletalsystem

Adrenalgland

PancreasTestis(male)

Ovary (female)

Hypothalamus

Pituitary gland

Thyroid gland

Parathyroidgland

Endocrinesystem

C D

F

E

BA

Excretory system disposes of certain wastes

Lymphatic and immune systems protect the body from infection and cancer

Reproductive system perpetuates the species

Digestive system absorbs food

Nervous system controls body functions



Lymphatic andimmune systems

G, H

Thymus

Bonemarrow

Spleen

Oviduct

Ovary

FemaleLymph nodes

Lymphaticvessels

Uterus

Vagina

Urinarysystem

Male

Brain

Seminal vesicles

Prostate gland

Vas deferens

Penis

Urethra

Testis

Sense organSpinalcord

Nervoussystem

Nerves

Esophagus

LiverStomachSmallintestine

Digestivesystem

Largeintestine

Anus

Mouth

Kidney

Ureter

Urinarybladder

Urethra

K

J

I

L

Reproductivesystem

20.12 The integumentary system protects the body

The skin consists of two layers

– Epidermis, at the surface

– Dermis, inner layer


Epidermis

Dermis

Hypodermis

Adipose tissue

Blood vessels

Hair follicle

Oil gland

Sweatgland

Sweatpore

Hair

Muscle

Nerve

Skin has many functions

– Epidermis

– Resists damage

– Decreases water loss

– Prevents penetration by microbes

– Dermis

– Sensory information

– Synthesis of vitamin D

– Temperature regulation


20.12 The integumentary system protects the body

EXCHANGES WITH THE EXTERNAL

ENVIRONMENT


20.13 Structural adaptations enhance exchange between animals and their environment

Animals must exchange materials with the environment

Respiratory system exchanges gases

Digestive system acquires food and eliminates wastes

Excretory system eliminates metabolic waste


External environment

MouthFood

Animal

CO2 O2

Respiratorysystem

d

Bloo

Digestivesystem

Heart

Nutrients Circulatorysystem

Intestine

Urinarysystem

Bodycells

Interstitialfluid

Anus

Unabsorbed matter (feces)

Metabolic wasteproducts (urine)

Adaptations that increase surface area promote exchanges with the environment


20.13 Structural adaptations enhance exchange between animals and their environment

Homeostasis is an internal steady state

20.14 Animals regulate their internal environment


Externalenvironment

Homeostaticmechanisms

Internalenvironment

Smallfluctuations

Largefluctuations

Humans promote homeostasis by

– Adding clothing when we are cold

– Drinking water when we are dehydrated

– Eating when our calories are running low

– Urinating when our bladders are full


20.14 Animals regulate their internal environment

Negative feedback mechanisms permit only small fluctuations around set points

20.15 Homeostasis depends on negative feedback


Animation: Negative Feedback

Animation: Positive Feedback

Sweat glands secrete sweatthat evaporates, cooling body

Blood vessels inskin dilate andheat escapes

Temperaturedecreases

Thermostat shuts offcooling mechanisms

Temperature risesabove normal

Temperature fallsbelow normal

Thermostat shuts offwarming mechanisms

Homeostasis:Internal body temperatureof approximately 36–38°C

Temperatureincreases

Blood vessels in skinconstrict, minimizingheat loss

Skeletal musclesrapidly contract,

causing shivering,which generates heat

Thermostat inbrain activateswarming mechanisms

Thermostat in brainactivates cooling

mechanisms

Epithelial (20.4) Connective (20.5) Muscle (20.6) Nervous (20.7)

Neurons withbranchingextensions

Long cells (fibers)with contractileproteins

Sparse cells inextracellularmatrix

Sheets of closelypacked cells

Protection,exchange,secretion

Binding andsupport ofother tissues

Movement ofbody parts

Transmission ofnerve signals

Fu

nct

ion

Str

uc

ture

Tis

sue

a.

b.

c.

d.

e.

You should now be able to

1. Explain the relationship between anatomy and physiology

2. Describe the structural hierarchy of the body from cell to organism

3. Explain how an animal’s form is influenced by its environment

4. Describe an example of convergent evolution

5. Describe the general structures and functions of the major tissues of the human body


6. Describe several recent advances of bioengineering

7. List and describe the functions of the major systems of the body

8. Explain how materials are exchanged between an organism and its environment

9. Define homeostasis and describe several examples


You should now be able to

THE HIERARCHY OF STRUCTURAL ORGANIZATION IN AN ANIMAL Copyright © 2009 Pearson Education, Inc.

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muscle tissue functions

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tissues connective tissue

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