sensory and motor mechanisms

SENSORY AND MOTOR MECHANISMS

The following PowerPoint Presentation consists of a concise overview of Chapter 49 in Campbell & Reece’s 7th Edition A.P. Biology Textbook, as well as a series of activities to correspond with each of the following systems covered: sensory, skeletal, and muscular. This PowerPoint Presentation is best viewed as a Slide Show. At the end there is a also a list of online resources to accompany your academic endeavors into this field of biology. Good Luck!!!

AAKAASH VARMA, ROCCO CAPITINI, MICHAEL SCIORTINO, CHRISTINA GOTSIS

SENSORY RECEPTORSTRANSDUCE STIMULUS ENERGY AND TRANSMIT SIGNALS TO THE CENTRAL NERVOUS SYSTEM

SENSORY RECEPTION

Sensations are action potentials that reach

brain via sensory neurons

Sensory reception involves stimulus

detection by sensory receptors

• Resulting interpretations by brain are called perceptions

• Exteroreceptors detect external stimuli

• Interoreceptors detect internal stimuli

TYPES OF SENSORY RECEPTORS

• Sense physical deformation• Bending of plasma membrane increases permeability to sodium and potassium

MECHANORECEPTORS

• Transmit information about total solute concentration of solution or individual molecules

• Involved in gustation (taste) and olfaction (smell)

CHEMORECEPTORS

• Detect electromagnetic energy (e.g. visible light, electricity, and magnetism)

ELECTROMAGNETIC

• Respond to heat/cold• Enable adaptation to regulate body temperature

THERMORECEPTORS

• Naked dendrites in epidermis• Enable detection of danger

NOCICEPTORS (A.K.A PAIN RECEPTORS)

SENSORY RECEPTOR FUNCTIONS

Transduction

• Stimulus energy converted into change in membrane potential (receptor potential)

• Result from opening/closing of ion channels in membrane of receptor

Amplification

• Stimulus energy strengthened by cells in sensory pathway

• May take place in sensory receptors or in accessory structures

Transmission

• Receptors release excitatory neurotransmitter, causing sensory neuron to transmit action potentials to the CNS

• Some may contain an axon, extending into the CNS, others release neurotransmitters at synapses.

Integration

• Begins when information is received• May include a decrease in responsiveness during

continued simulation (sensory adaptation)• Involves selectivity of receptors in the

information transmitted to CNS

VISION (SEEING)

Light enters thru pupil, regulated by size-changing iris

Reaches retina where it is captured by specific

photoreceptors, rods and cones, which distinguish b/w shapes

and colors, respectively

Upon activation by light, rod cells become polarized, and thus

(de)activate neuronal, bipolar cells that transmit light signals through the optic nerve to brain

AUDITION (HEARING)

Tympanic membrane vibrates at same frequency as sound waves traveling thru auditory canal

Causes small bones to transmit vibrations to the oval window, which creates pressure waves in cochlea fluid, which transmit waves to

round window

Hair cells of basilar membrane brush against tectorial membrane, creating changes in polarization

Lead to increased/decreased neurotransmitter release to auditory nerve

GUSTATION (TASTE)

Chemoreceptors in taste buds of tongue, bind to specific molecules

Once bound, ions diffuse through channels in plasma membrane until they reach sensory neurons, initiating a signal transduction

pathway

Ions are then transferred to sensory neurons as neurotransmitters

OLFACTION (SMELLING)

Olfactory receptor cells use odorant receptors of

chemoreceptors to bind to odorant molecules as they pass

thru nasal cavity

These trigger signal transduction pathways that, when reaching brain’s olfactory bulbs, create

action potentials that allow brain to identify/distinguish odor

TACTION (TOUCHING)

ACTIVITY: what receptor would you use to sense…

THE AURORA BOREALIS?

A PHOTORECEPTOR, A TYPE OF ELECTROMAGNETIC RECEPTOR!


MUSIC?

A MECHANORECEPTOR!


PERFUME?

AN ODORANT RECEPTOR, A TYPE OF CHEMORECEPTOR!


PAIN?

A NOCICEPTOR (A.K.A PAIN RECEPTOR)!


PIZZA?

A CHEMORECEPTOR!


HEAT?

A THERMORECEPTOR!

ANIMAL SKELETONSFUNCTION IN SUPPORT, PROTECTION, AND MOVEMENT

TYPES OF SKELETONS

HYDROSTATIC• Fluid held under pressure in

closed body compartment• Muscles to change shape of

fluid-filled compartments to allow for locomotion and form

• Cushions organs from shock• Well suited for aquatic

environments but supports crawling/burrowing on land

• Main type of skeleton in most cnidarians, flatworms, nematodes, and annelids

EXOSKELETON• Hard encasement deposited

on surface• Molluscs: hinged calcareous

(calcium carbonate) shells • Arthropods: cuticles

composed of chitin in a protein matrix and hardened by calcium salts• Molting occurs w/ each

growth spurt

ENDOSKELETON• Hard supporting elements

buried w/in soft tissues• Sponges: hard spicules of

inorganic material or by softer protein fibers

• Echinoderms: hard plates (ossicles)

• Chordates: cartilage/bone• Axial skeleton: skull,

vertebral column, and rib cage

• Appendicular skeleton: limb bones and appendage-anchoring pectoral/pelvic girdles

• Joints provide flexibility for body movements

HUMAN SKELETAL SYSTEM

ACTIVITY: what skeleton would this animal have…

• Can survive in most different types of environments if nourished well• Has many supporting elements to

provide physical support on land• Has a great range of flexibility

AN ENDOSKELETON (HUMAN)!


• Lives in moist soil• Moves by a process known as

peristalsis• It is not raised off ground and is

known to crawl and burrow

A HYDROSTATIC SKELETON (EARTHWORM)!


• Lives near abrasive shore• Requires shielding from dangerous

materials, desiccation, and predators

• Must molt periodically

AN EXOSKELETON (LOBSTERS)!


• Locomotion occurs by muscular alteration of body cavities

• Subject to shock frequently• Stays close to ground

A HYDROSTATIC SKELETON (FLATWORMS)!


• Extremely flexible• Has many soft tissues

•Requires a great deal of movement

AN ENDOSKELETON (MAMMALS)!


• Very fragile and require protection• Present in many habitats

• Growth requires many moltings

AN EXOSKELETON (INSECTS)!

MUSCLESOCCUR IN ANTAGONISTIC PAIRS AND MOVE SKELETAL PARTS BY CONTRACTING

SKELETAL MUSCLE STRUCTURE

MUSCLE FIBER-BUNDLES – each consist of a single, multi-nuclear

cell

MYOFIBRILS – thin actin and thick myosin myofilaments that are bundled to form each muscle

fiber

SARCOMERES – contractile units of muscle that repeat in unit-like frequencies in each myofibril

I BAND, A BAND, and H ZONE – contain myofilaments

Z LINES – single actin filaments that form its boundaries

SLIDING-FILAMENT MODEL

Thin (actin) filaments

slide across thick

(myosin) filaments

Reduces width of I

bands and H zone

Shortens

sarcomere

Shortening of all

sarcomeres in a myofibril shortens

entire myofibril

UNDERLYING INTERACTIONS

REGULATION

NEURAL CONTROL

Graded contractions of whole muscles can be caused by:

Varying number of muscle fibers that contract

Each branched muscle fiber is innervated by 1 motor neuron that may synapse w/ multiple muscle fibers

MOTOR UNIT – 1 motor neuron and its controlled muscle fibers

RECRUITMENT – activation of additional motor neurons increases force (tension)

Varying rate at which muscle fibers are stimulated

1 action potential in a motor neuron produces a twitch

More rapidly delivered action potentials produce a graded contraction by summation

TETANUS – fusion of twitches into a sustained contraction

TYPES OF MUSCLE FIBERS

Brownish-red pigment that binds

oxygen

OTHER TYPES OF MUSCLE

CARDIAC MUSCLE• Found only in heart• Striated cells that are

electrically connected by intercalated discs

• Can generate action potentials w/o input from nervous system

SMOOTH MUSCLE• Found in walls of hollow organs• Lack striations b/c their

actin/myosin filaments are not regularly arrayed along cell length

• Contract slowly, but to a greater range than striated muscles

• Contractions can be initiated by electrically coupled muscles themselves or stimulated by neurons of autonomic nervous system

ACTIVITY: what is the password…

• Arranged longitudinally bundles of this comprise a muscle fiber• Made of myofilaments

MYOFIBRIL!


•Bind to troponin complex to expose myosin-binding sites on thin

filament, allowing for contraction

CALCIUM (Ca2+) IONS!


• Repeating unit of a pattern of light/dark bands, arranged by

myofilaments

SARCOMERE!


• Filament w/ two strands of actin, and a strand of regulatory protein

THIN FILAMENT!


• Collective term for a motor neuron and its controlled muscle fibers

MOTOR UNIT!


• Sustained contraction brought about by fusion of twitches that

occur in quick succession

TETANUS!


•Its membrane pumps calcium (Ca2+) ions from the cytosol into its interior

to store them and releases them when an action potential is

produced

SARCOPLASMIC RETICULUM!


• Regulatory protein that blocks myosin-binding sites, keeping fiber

at rest

TROPOMYOSIN!


• 1 cell w/ multiple nuclei, running muscle length

MUSCLE FIBER!


• Infoldings of plasma membrane along which action potentials move

to spread deep into a fiber

TRANSVERSE (T) TUBULES!

ONLINE RESOURCES

SENSORY SYSTEM:•http://frank.mtsu.edu/~jshardo/bly2010/nervous/receptor.html•http://www.spc.cc.tx.us/biology/mhartgraves/Bio2401/Lecture%20Notes/Sensory.pdf•http://www.biology-online.org/9/8_sensory_systems.htm•http://www.slideshare.net/NeurologyGuru/sensory-systemSKELETAL SYSTEM:•http://www.mnsu.edu/emuseum/biology/humananatomy/skeletal/skeletalsystem.html•http://www.innerbody.com/image/skelfov.html•http://lyndarandy.tripod.com/skeletalsystem/id1.htmlMUSCULAR SYSTEM:•http://www.youtube.com/watch?v=EdHzKYDxrKc•http://www.human-body-facts.com/muscular-system.html•http://www.youtube.com/watch?v=gJ309LfHQ3M&feature=related•http://www.besthealth.com/besthealth/bodyguide/reftext/html/musc_sys_fin.html•http://www.ivy-rose.co.uk/HumanBody/Muscles/Muscle_Sliding-Filament.php

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