AP Biology 2006-2007 Muscles & Motor Locomotion Why Do We Need All That ATP?

2006-2007AP Biology

Muscles & Motor Locomotion

Why Do We Need All

That ATP?

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Animal LocomotionWhat are the advantages of locomotion?

motilesessile

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Lots of ways to get around…

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mollusk mammalbird reptile

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bird arthropodmammal bird

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Muscle

voluntary, striated

involuntary, striated

auto-rhythmic

involuntary,

non-striated

evolved first

multi-nucleated

digestive systemarteries, veins

heartmoves bone

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tendon

skeletal muscle

muscle fiber (cell)

myofilamentsmyofibrils

plasma membrane

nuclei

Organization of Skeletal muscle

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Human endoskeleton

206 bones

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Muscles movement Muscles do work by contracting

skeletal muscles come in antagonistic pairs flexor vs. extensor

contracting = shortening move skeletal parts

tendons connect bone to muscle

ligaments connect bone to bone

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Structure of striated skeletal muscle Muscle Fiber

muscle cell divided into sections = sarcomeres

Sarcomere functional unit of muscle

contraction alternating bands of

thin (actin) & thick (myosin) protein filaments

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Muscle filaments & Sarcomere

Interacting proteins thin filaments

braided strands actin tropomyosin troponin

thick filaments myosin

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Thin filaments: actin Complex of proteins

braid of actin molecules & tropomyosin fibers tropomyosin fibers secured with troponin molecules

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Thick filaments: myosin Single protein

myosin molecule long protein with globular head

bundle of myosin proteins:globular heads aligned

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Thick & thin filaments Myosin tails aligned together & heads pointed

away from center of sarcomere

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Interaction of thick & thin filaments Cross bridges

connections formed between myosin heads (thick filaments) & actin (thin filaments)

cause the muscle to shorten (contract)

sarcomere

sarcomere

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Where is ATP needed?

3

4

12

1

1

1

Cleaving ATP ADP allows myosin head to bind to actin filament

thin filament(actin)

thick filament(myosin)

ATP

myosin head

formcrossbridge

binding site

So that’s where those

10,000,000 ATPs go!Well, not all of it!

ADP

releasecrossbridge

shortensarcomere

1

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Closer look at muscle cell

multi-nucleated

Mitochondrion

Sarcoplasmicreticulum

Transverse tubules(T-tubules)

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Muscle cell organelles Sarcoplasm

muscle cell cytoplasm contains many mitochondria

Sarcoplasmic reticulum (SR) organelle similar to ER

network of tubes stores Ca2+

Ca2+ released from SR through channels Ca2+ restored to SR by Ca2+ pumps

pump Ca2+ from cytosol pumps use ATP

Ca2+ ATPase of SR

ATP

There’sthe restof theATPs!

But whatdoes theCa2+ do?

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Muscle at rest Interacting proteins

at rest, troponin molecules hold tropomyosin fibers so that they cover the myosin-binding sites on actin troponin has Ca2+ binding sites

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The Trigger: motor neurons Motor neuron triggers muscle contraction

release acetylcholine (Ach) neurotransmitter

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Nerve signal travels down T-tubule

stimulates sarcoplasmic reticulum (SR) of muscle cell to release stored Ca2+

flooding muscle fibers with Ca2+

Nerve trigger of muscle action

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At rest, tropomyosin blocks myosin-binding sites on actin secured by troponin

Ca2+ binds to troponin shape change

causes movement of troponin

releasing tropomyosin exposes myosin-

binding sites on actin

Ca2+ triggers muscle action

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How Ca2+ controls muscle Sliding filament model

exposed actin binds to myosin

fibers slide past each other ratchet system

shorten muscle cell muscle contraction

muscle doesn’t relax until Ca2+ is pumped back into SR requires ATP

ATP

ATP

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Put it all together…1

ATP

2

3

4

5

7

6

ATP

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How it all works… Action potential causes Ca2+ release from SR

Ca2+ binds to troponin

Troponin moves tropomyosin uncovering myosin binding site on actin

Myosin binds actin uses ATP to "ratchet" each time releases, "unratchets" & binds to next actin

Myosin pulls actin chain along Sarcomere shortens

Z discs move closer together

Whole fiber shortens contraction! Ca2+ pumps restore Ca2+ to SR relaxation!

pumps use ATP

ATP

ATP

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Fast twitch & slow twitch muscles Slow twitch muscle fibers

contract slowly, but keep going for a long time more mitochondria for aerobic respiration less SR Ca2+ remains in cytosol longer

long distance runner “dark” meat = more blood vessels

Fast twitch muscle fibers contract quickly, but get tired rapidly

store more glycogen for anaerobic respiration sprinter “white” meat

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Muscle limits Muscle fatigue

lack of sugar lack of ATP to restore Ca2+ gradient

low O2 lactic acid drops pH which

interferes with protein function synaptic fatigue

loss of acetylcholine

Muscle cramps build up of lactic acid ATP depletion ion imbalance

massage or stretching increases circulation

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Diseases of Muscle tissue ALS

amyotrophic lateral sclerosis Lou Gehrig’s disease motor neurons degenerate

Myasthenia gravis auto-immune antibodies to

acetylcholine receptors

Stephen Hawking

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Botox Bacteria Clostridium botulinum toxin

blocks release of acetylcholine botulism can be fatal muscle

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Rigor mortis So why are dead people “stiffs”?

no life, no breathing no breathing, no O2

no O2, no aerobic respiration no aerobic respiration, no ATP no ATP, no Ca2+ pumps Ca2+ stays in muscle cytoplasm muscle fibers continually

contract tetany or rigor mortis

eventually tissues breakdown& relax measure of time of death

2006-2007AP Biology

So don’t be a stiff!Ask Questions!!

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The way it ISN’T: sensing brain analysis action.

The way it is: sensing, analysis, and action are ongoing and overlapping processes.

Sensations begin as different forms of energy that are detected by sensory receptors. This energy is converted to action potentials

that travel to appropriate regions of the brain. The limbic region plays a major role in determining

the importance of a particular sensory input.

Processing of input and output is cyclical

Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings

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Sensations are action potentials that reach the brain via sensory neurons.

Perception is the awareness and interpretation of the sensation.


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Signal Transduction Pathway


Fig. 49.2

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Sensory reception begins with the detection of stimuli by sensory receptors. Exteroreceptors detect stimuli originating

outside the body. Interoreceptors detect stimuli originating

inside the body.


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Transduction. The conversion of stimulus energy into a

change in membrane potential. Amplification.

The strengthening of stimulus energy that is can be detected by the nervous system.

Transmission. The conduction of sensory impulses to the

CNS. Integration.

The processing of sensory information.Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings

Sensory Processing

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Sensory receptors are categorized by the type of energy they transduce


Fig. 49.3

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Mechanoreceptors respond to mechanical energy. Pain receptors = nocioceptors.

Different types of pain receptors respond to different types of pain.

Thermoreceptors respond to heat or cold. Respond to both surface and body core

temperature.

Chemoreceptors respond to chemical stimuli. Electromagnetic receptors respond to

electromagnetic energy. Photoreceptors respond to the radiation we know as

visible light.Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings

Sensory Receptors

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Vertebrates have single-lens eyes


Fig. 49.9

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Sclera: a tough white layer of connective tissue that covers all of the eyeball except the cornea.

Conjunctiva: external cover of the sclera that keeps the eye moist.

Cornea: transparent covering of the front of the eye. Allows for the passage of light into the eye and functions as

a fixed lens. Choroid: thin, pigmented layer lining the interior surface of the

sclera. Prevents light rays from scattering and distorting the image. Anteriorly it forms the iris.

The iris regulates the size of the pupil. Retina: lines the interior surface of the choroid.

Contains photoreceptors.


Parts of Vertebrate Eye

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Photoreceptors of the retina.

About 125 million rod cells. Rod cells are light sensitive but do not

distinguish colors.About 6 million cone cells.

Not as light sensitive as rods but provide color vision.

Most highly concentrated on the fovea, an area of the retina that lacks rods.


AP BiologyCopyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings

Fig. 49.15


The optic nerves of the two eyes meet at the optic chiasm. Where the nasal half of each

tract crosses to the opposite side.

Ganglion cell axons make up the optic tract. Most synapses in the

lateral geniculate nuclei of the thalamus. Neurons then convey

information to the primary visual cortex of the optic lobe.

Fig. 49.16

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The outer ear includes the external pinna and the auditory canal.Collects sound waves and channels

them to the tympanic membrane (ear drum).

Hearing organ is within the ear



Fig. 49.17

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From the tympanic membrane sound waves are transmitted through the middle ear.

Malleus incus stapes.From the stapes the sound wave is

transmitted to the oval window and on to the inner ear.

The eustachian tube connects the middle ear with the pharynx.


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Taste receptors in insects are located on their feet.

Perceptions of taste and smell are usually interrelated


Fig. 49.23

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In mammals, taste receptors are located in taste buds, most of which are on the surface of the tongue.

Each taste receptor responds to a wide array of chemicals. It is the pattern of taste receptor response

that determines perceived flavor.


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AP Biology 2006-2007 Muscles & Motor Locomotion Why Do We Need All That ATP?