animal bodies and homeostasis

8/7/2019 Animal Bodies and Homeostasis

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Animal bodies andhomeostasis

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Chapter 40


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All animal cells share similarities in the waysin which they

Exchange materials with their surroundings

Obtain energy from organic nutrients

Synthesize complex molecules

Reproduce themselves

Detect and respond to signals in theirimmediate environment

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Cells with similar properties group to form

tissues Tissues combine with other types of tissues to

form organs Organs are anatomically or functionally linked to

form organ systems 33


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Tissues

Specialized cells of a given type clustertogether

4 categories

Muscle

Nervous

EpithelialConnective

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Muscle tissue

Cells specialized to contract generating force

3 types

Skeletal attached to bone or exoskeletonfor locomotion, voluntary control

Smooth surrounds hollow tubes andcavities for propulsion of contents,

involuntary control

Cardiac only in the heart, involuntarycontrol

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Bronchiole

Lungs

Heart

Smoothmusclelayer

Smoothmusclelayer

Smoothmusclecells

Skeletalmusclecell

Cardiacmusclecell

(left): Michael Abbey/Photo Researchers, Inc.; (middle): Sinclair Stammers/Photo Researchers, Inc.;(right): Dr. Richard Kessel/Visuals Unlimited


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Nervous tissue

Initiate and conduct electrical signals fromone part of the animals body to another

Single nerve cell called a neuron

Electrical signals produced in one nerve cellmay stimulate or inhibit other nerve cells to

Initiate new electrical signals

Stimulate muscle to contractStimulate glands to release chemicals

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Spinal cord


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Epithelial tissues

Sheets of densely-packed cells that

Cover the body or individual organs

Line the walls of body cavitiesSpecialized to protect and secrete or absorb

All are asymmetrical or polarized

Rest on basal lamina or basementmembrane

Can function as selective barriers

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Basillamina

Nasal passage:

Pseudostratified ciliated columnar

Kidney tubules:Simple cuboidal

Esophagus lining:Stratified squamous

Lungs:

Simple squamous

Intestines:Simple columnar

Urinary system:Transitional


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Connective tissues

Connect, anchor, and support

Includes blood, adipose, bone, cartilage,loose and dense connective tissue

Form an extracellular matrix around cells

Provides scaffold for attachment

Protects and cushions

Mechanical strength

Transmit information

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Blood

Adipose tissue

Bone

Cartilage

192 m

Dense connectivetissue

Loose connectivetissue

160 m160 m

(inset a): Dennis Kunke Microscopy/Phototake; (inset b): Ed Reshke/Peter Arnold; (inset c): Innerspace Imaging/Photo Researchers,

Inc.; (inset d): Dr. John D. Cunningham/Visuals Unlimited; e-f: The McGraw-Hill Companies, Inc./Al Tesler, photographer


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Organs

Composed of 2 or more kinds of tissues

Organ system different organs worktogether to perform an overall function

Organ systems frequently work together nervous and endocrine system

Spatial arrangement of organs into organsystems part of overall body plan

Body plan controlled by highly conservedfamily of genes with homologs in all animals

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Stomach

Intestine

Nervous tissue

Connective tissue

Connective tissue

Lumen of stomach

Simple squamousepithelial tissue

Layers of smoothmuscle tissue

Small arteryand vein

Simple columnarepithelial tissue

Layers ofmuscle tissue


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Organ Development andFunction Are Controlled by

Homeotic GenesHomeotic genes family of ancient highlyconserved genes found in all animals

Determine timing and spatial patterning of theanteroposterior body axis during development

In vertebrates known as Hoxgenes

Important role in determining where organs

formHoxgenes also important for growth,development and function of organs in adults


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Body fluids

2 main compartments

Intracellular fluid inside cells

Extracellular fluid outside cells

Plasma fluid portion of blood

Interstitial fluid fluid between cells

In vertebrates, kept separate

In invertebrates, intermingled fluid calledhemolymph

Intracellular and extracellular fluid can bevery different in solute composition

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Plasma

Blood vessel (capillary)

Intracellularfluid

Interstitialfluid

Extracellularfluid

Red

bloodcell



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Movement of solutes

Passive diffusion

Movement of a solute down its concentrationgradient

No carrier or ATP required

Only nonpolar or extremely small polarsolutes

Rate of diffusion depends on Concentration gradient

Area for diffusion

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Movement of most solutes betweencompartments or across plasma membranesis mediated by transport proteins

Facilitated diffusion passiveActive transport

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Movement of water

Plasma membranes tend to be highly permeableto water and

Fluid moves readily between compartments

Osmosis

Swollen or shrunken cells are more fragile and willdie if membrane ruptures

Can happen when cells exposed to more dilute(hypoosmotic) or more concentrated(hyperosmotic) extracellular fluids

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When red blood cells swell, they mayburst, a phenomenon called hemolysis Shrinkage of red blood cells is called

crenation

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Form and function are

closely relatedCompare respiratory systems of insect andmammal

Structural similarities suggest similar

function

Tubes connect with the outside environmentterminating in 1 cell thick structures

Tubes serve as air conduits

Thin cells with high surface area for diffusionof gases

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(a) Insect respiratory system

Body surface

Spiracle

Air

Air

Tracheae

(b) Human respiratory system

Strip of skeletalmuscle

Trachea(pseudostratifiedciliated epithelium)

Alveoli


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All respiratory organs have an extensive surface area

All cells, tissues, and organs that mediate diffusionrequire extensive surface area

Maximizes abilityIncreasing surface area comes at expense of greatlyincreasing volume without shape change

SA/V surface area to volume ratio

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Homeostasis

Process of maintaining a relatively stableinternal environment despite changes in theexternal surroundings

Conformers maintain same fluidcomposition as environment cheaper

Regulators internal composition of fluidsdifferent from environment more expensive

Animal can be both with respect to differentvariables

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No physiological function is constant for very

long, which is why we call them variablesNormally, blood sugar (glucose) remains atfairly steady and predictable levels in anyhealthy individual

After a meal the level of glucose in yourblood can increase quickly

If you skip a meal, your blood sugar level

may drop slightly

Homeostatic mechanisms restore bloodglucose to normal levels in the blood

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Homeostatic controlsystems

Set point normal value for controlledvariable

Sensor monitors particular variable

Integrator compares signals from thesensor to set point

Effector compensates for deviations

between actual value and set point

Example body temperature in mammals

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Homeostatic challenge(cooling)

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Sensor(neurons)

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Sensor

(neurons)

Integrator(in brain)

Set point: 37CInput:


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Sensor(neurons)

Integrator(in brain)

Set point: 37CInput:


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Sensor(neurons)

Integrator(in brain)Set point: 37C

Input:

animal bodies and homeostasis

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