•  Alta  concentração  de  substância  intercelular  (Matriz)  

•  Al7ssima  diversidade  celular  e  funcional  •  Conecta  outros  tecidos    

•  Con s< t u í d a   p r i n c i p a lmen t e   p o r   á g u a ,  polissacarídeos  e  proteínas:  

Ø Colágeno:  Resistência  Ø Elas<na:  Elas<cidade  Ø Re<culina:  Maleabilidade  

 

Preenchimento

Eritrócitos, Leucócitos e plaquetas

Plasma

1. "]jO'tiil Sketch a Bcell receptor. Label the VandC regions of the light and heavy chains. Now markthe positions of the antigen-binding sites, disulfidebridges, and transmembrane regions. How do thepositions of these features relate to the location ofthe variable and constant regions?

2. Explain two advantages of having memory cells whena pathogen is encountered for a second time.

3. -'..Mill. Ifboth copies of a light-chain gene and aheavy-chain gene recombined in each Bcell, howwould this affect Bcell development?For suggested answers. see Appendix A

CONc£pr CH£CI( 43.2

defends againstinfection of body cells and fluids

Acquired immunity is based on both a humoral immune re-sponse and a cell-mediated immune response (figure 43.16).The humoral immune response involves the activation andclonal selection of effector B cells, which secrete antibodiesthat circulate in the blood and lymph. The humoral responseis so named because blood and lymph were long ago cailedbody humors. It is also called the antibody-mediated responsebecause of the key role of antibodies. The predominantcell-mediated immune response involves the activation and

Humoral (antibody-mediated) immune response Ceil-mediated immune response

Ant,gen (lst exeosure)K.,.... Stimulates

Gives rise to

Antigen-presenting (el! o )

Bcell o Helper T cell o • Cytotoxic T cell

MemoryHelper T cells

•.Antigen (2nd exposure)_. ...Memory B cellsPlasma cells

t

Defend against extracellular pathogens by binding to ant'gens.thereby neutralizing pathogens or makmg them better targetsfor phagocytes and complement proteins.

!Defend against intracellular pathogensand cancer by binding to and lysing theinfected cells or cancer cells.

• Figure 43.16 An overview of the acquired immune response.II Identify each black or brown arrow as representing part of the primary or secondary response

942 UNIT SEVEN Animal Form and Function

Ø Avascular e sem nervos

Ø Pericôndrio

Osteócitos e Osteoblastos e Osteoclastos

Ø Fosfato de Cálcio

Ø Colágeno

Ø Sustentação

Ø Locomoção

Ø Medula óssea vermelha

Ø Células tronco

Ø 

Ø 

Ø  Epiderme

Ø 

Ø  Derme

Ø 

Subcamada:

Ø  Hipoderme

.. Figure 50.26 The Sarcomeresliding-filamentmodel of muscle Z M Zcontraction. The 3 Edrawings on the left Relaxed •show that the lengths muscle "of the thick (myosin)filaments (purple) andthin (actin) filaments ,-(orange) remain the Contracting • •same as amuscle fiber muscle • •contracts,

Fully contracted - -muscle - -, Contracted ,,- -, Sarcomere

Thin filaments

rCk filament- o Starting here, the myosin head

is bound to ATP and is in itslow-energy configuration

"Binding of a new mol-ecule of ATP releases themyosin head from actin,and a new cycle begins.

yV,f'., ..filament

head (low-energy configuration)

myosin head hydrolyzes:: ,ATPto ADP and inorganicThICk phosphate (®) and is in itsfilament high-energy configuration

...Thin filament movestoward center of sarcomere. Actin

Myosinbinding sites

Myosin head (low-energy configuration)

head (high-energy configuration)

... Figure 50.27 Myosin-actin interactions underlying muscle fiber contraction.II When ATP binds, what prevents the filaments from sliding back into their original positions)

o Releasing ADP and ®' myosinreturns to its low-energy configuration,sliding the thin filament.

/0Th, my,,;c h"d b;cd,to actin, forming across-bridge,

o Visit the Study Areaat www.masteringbio.comfor the BioFlix 3-D Animatioo onMuscle Cootractioo.

CHfJ,PTER fifTY Sensory and Motor Mechanisms 1107

...no  estado  de  repouso  (músculo  relaxado)  a  miosina  não  consegue  se   ligar   à   ac8na   porque   os   sí8os  de   ligação   estão   obstruídos   pela  tropomiosina...  

Ø O   cálcio   liga-­‐se   à   troponina   e   remove   a  tropomiosina   liberando   os   sí8os   de   ligação  da  ac8na  para  a  cabeça  da  miosina.  

 

MIOFIBRILAS  

CISTERNAS    LATERAIS  

RETÍCULO  SARCOPLASMÁTICO  

TÚBULOS  (T)  TRANSVERSOS  

• fIgun 5G.29

Exploring The Regulation of Skeletal Muscle Contraction

released ftomSarcomere sarcoplasmic reticulum

Mltochondnon

Motorneuron axon

Synapticterminal

"""" ---'E"''''membraneof muscle fiber

The electrical, chemical, and molecular eventsregulating skeletal muscle contraction are shown in acutaway view of a muscle cell and in the enlarged crosssection below. Action potentials (red arrows) triggeredby the motor neuron sweep across the muscle fiberand into it along the transverse (T) tubules, initiatingthe movements of calcium (green dots) that regulatemuscle activity. T tubule

o Action potentialtriggersrelease fromsarcoplasmicreticulum (SR).

Plasma membrane

• •

•

SR

I

•

{) Myosm cross-bndges alternately attach to actinand detach, pulling thin filament toward Cl!nterof sarcomere; ATP sliding of filaments

o 0 0 0 0

0 0 ogg 000 0 g 0

o 0 0 0 g 0 Calcium ions bind to troponin•00 0 in thin filament; myosin-o 0 0 0 0 binding sites exposed,! •

Ca2'

•e ActIOn potentJalrspropagated alongplasma membraneand down Ttubules.

•o Cytosobc Ca2- isremoved by adlve

o transport IntoSR aftl!r actionpotential ends.

•

•

o Acetylcholine (ACh) released at synaphc termmal diffuses acrosssynaptIC: deft and binds to receptor on muscle fiber'splasma membrane, triggenng an ilGIOIl potential In muscle ilber

TTubule

I--.::--::.-' .o 0 AT 0• • •• •••

o 0 0 CYTOSOL• •o Tropomyosin blockage of myosin- •binding Sites is restored; contradlon

ends, and muscle fiber relaxes.

(HAHU flnY Sensory and Motor Mechanisms 1109