ohhs ap biology chapter 50 (class presentation)

52
Chapter 50 Sensory and Motor Mechanisms

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Page 1: OHHS AP Biology Chapter 50 (Class Presentation)

Chapter 50Sensory and Motor Mechanisms

Page 2: OHHS AP Biology Chapter 50 (Class Presentation)

Complex sensory systems that facilitate survival.

Page 3: OHHS AP Biology Chapter 50 (Class Presentation)

Bats use sonar to detect prey.

Page 4: OHHS AP Biology Chapter 50 (Class Presentation)

Moths can detect the bat’s sonar.

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Include diverse mechanisms that sense stimuli and generate appropriate movement.

Page 6: OHHS AP Biology Chapter 50 (Class Presentation)

All stimuli represent forms of energy.

Sensation involves converting energy into a change in the membrane potential of sensory receptors.

Page 7: OHHS AP Biology Chapter 50 (Class Presentation)

All stimuli represent forms of energy.

Function of sensory pathways: sensory reception, transduction, transmission, an integration.

Page 8: OHHS AP Biology Chapter 50 (Class Presentation)

Sensation and perceptions begin with sensory reception.

Detection of stimuli by receptors – both inside and outside of the body.

Page 9: OHHS AP Biology Chapter 50 (Class Presentation)

Sensory transduction: conversion of stimulus energy into change of membrane potential.

Change is called receptor potential – many are very sensitive.

Page 10: OHHS AP Biology Chapter 50 (Class Presentation)

Transmission: sensory cell facilitate the movement of action potentials.

Larger receptor potential = more rapid action potentials.

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Integration: receptor potentials integrated through summation.

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Perception: the brain’s construction of stimuli

Brain distinguishes stimuli from different receptors by the area where the action potentials arrive.

Page 13: OHHS AP Biology Chapter 50 (Class Presentation)

Type of Sensory Receptors

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Mechanoreceptors: sense physical deformation.

TOUCH!

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Chemoreceptors: information about the total solute concentration of a solution.

Respond to individual kinds of molecules.

Page 16: OHHS AP Biology Chapter 50 (Class Presentation)

Electromagnetic receptors: detect electromagnetic energy such as light, electricity and magnetism.

Page 17: OHHS AP Biology Chapter 50 (Class Presentation)

Thermoreceptors: respond to heat or cold.

Regulate body temp. by signaling both surface and core temp.

Page 18: OHHS AP Biology Chapter 50 (Class Presentation)

Nociceptors: naked dendrites in the epidermis.

Pain receptors.

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Hearing and perception of body equilibrium are related in most animals.

Mechanoreceptors

Page 20: OHHS AP Biology Chapter 50 (Class Presentation)

Most invertebrates maintain equilibrium using statocysts.

Detect movement of granules called statoliths.

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Many arthropods sense sounds with body hairs that vibrate.

“Ears” consisting of tympanic membrane and receptor cells.

Page 22: OHHS AP Biology Chapter 50 (Class Presentation)
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Vibrations create percussion waves that vibrate tympanic membrane.

Bones of the middle ear transmit the vibrations.

Page 24: OHHS AP Biology Chapter 50 (Class Presentation)

Vibrations create waves of fluid that move through vestibular canal.

Waves cause the basilar membrane to vibrate, bending hair cells.

Page 25: OHHS AP Biology Chapter 50 (Class Presentation)

Bending of hair cells depolarizes the membranes.

Sends action potential to the brain via the auditory nerve.

Page 26: OHHS AP Biology Chapter 50 (Class Presentation)

Ear conveys information about volume and pitch.

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Fishes have only a pair of inner ears near the brain.

Also have lateral line system that detect and respond to water movement.

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Taste and smell rely on similar set of sensory receptors.

Terrestrial animals:Gustation: Taste, detection of chemicals called tastants.Olfaction: Smell, detection of odorant molecules.

Page 29: OHHS AP Biology Chapter 50 (Class Presentation)

Taste and smell rely on similar set of sensory receptors.

Taste buds detect five taste perceptions: sweet, sour, salty, butter, and umami – different regions of the tongue.

Page 30: OHHS AP Biology Chapter 50 (Class Presentation)

Olfactory receptors are neurons that line the upper portion of the nasal cavity.

Page 31: OHHS AP Biology Chapter 50 (Class Presentation)

Muscle Function

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Muscle activity is a response to input from the nervous system.

The action of a muscle is always to contract.

Page 33: OHHS AP Biology Chapter 50 (Class Presentation)

• Skeletal muscle characterized by a hierarchy of smaller and smaller units.

• Consists of a bundle of long fibers – each a single cell – running the length of the muscle.

• Each muscle fiber is a bundle of smaller myofibrils.

Page 34: OHHS AP Biology Chapter 50 (Class Presentation)

Two kinds of myofilaments.

Thin: two strands of actin, one strand of regulatory protein.

Thick: staggered arrays of myosin molecules.

Page 35: OHHS AP Biology Chapter 50 (Class Presentation)

Skeletal muscle also called striated muscle – arrangement of myofilaments create light and dark bands.

Functional unit of a muscle is called a sarcomere – bordered by Z lines.

Page 36: OHHS AP Biology Chapter 50 (Class Presentation)

Sliding-filament model: filaments slide past each other, producing overlap.

Based on interaction between actin of thin filaments and myosin of the thick filaments.

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Fig. 50-27-1

Thinfilaments

ATP Myosin head (low-energy configuration

Thick filament

Thin filament

Thickfilament

Page 38: OHHS AP Biology Chapter 50 (Class Presentation)

Fig. 50-27-2

Thinfilaments

ATP Myosin head (low-energy configuration

Thick filament

Thin filament

Thickfilament

Actin

Myosin head (high-energy configuration

Myosin binding sites

ADP

P i

Page 39: OHHS AP Biology Chapter 50 (Class Presentation)

Fig. 50-27-3

Thinfilaments

ATP Myosin head (low-energy configuration

Thick filament

Thin filament

Thickfilament

Actin

Myosin head (high-energy configuration

Myosin binding sites

ADP

P i

Cross-bridgeADP

P i

Page 40: OHHS AP Biology Chapter 50 (Class Presentation)

Fig. 50-27-4

Thinfilaments

ATP Myosin head (low-energy configuration

Thick filament

Thin filament

Thickfilament

Actin

Myosin head (high-energy configuration

Myosin binding sites

ADP

P i

Cross-bridgeADP

P i

Myosin head (low-energy configuration

Thin filament movestoward center of sarcomere.

ATP

ADP P i+

Page 41: OHHS AP Biology Chapter 50 (Class Presentation)

Skeletal muscle fiber contract only when stimulated by a motor neuron.

Muscle at rest, myosin-binding sites on thin filament blocked by protein tropomyosin.

Page 42: OHHS AP Biology Chapter 50 (Class Presentation)

• For a muscle fiber to contract, myosin-binding sites must be uncovered

• This occurs when calcium ions (Ca2+) bind to a set of regulatory proteins, the troponin complex

• Muscle fiber contracts when the concentration of Ca2+ is high; muscle fiber contraction stops when the concentration of Ca2+ is low

Page 43: OHHS AP Biology Chapter 50 (Class Presentation)

• The synaptic terminal of the motor neuron releases the neurotransmitter acetylcholine

• Acetylcholine depolarizes the muscle, causing it to produce an action potential

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Action potentials travel to the interior of the muscle fiber along transverse (T) tubules

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The action potential along T tubules causes the sarcoplasmic reticulum (SR) to release Ca2+

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The Ca2+ binds to the troponin complex on the thin filaments

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This binding exposes myosin-binding sites and allows the cross-bridge cycle to proceed

Page 48: OHHS AP Biology Chapter 50 (Class Presentation)

Types of Skeletal Muscle Fibers• Skeletal muscle fibers can be classified

– As oxidative or glycolytic fibers, by the source of ATP

– As fast-twitch or slow-twitch fibers, by the speed of muscle contraction

Page 49: OHHS AP Biology Chapter 50 (Class Presentation)

Oxidative and Glycolytic Fibers• Oxidative fibers rely on aerobic respiration to

generate ATP• These fibers have many mitochondria, a rich

blood supply, and much myoglobin• Myoglobin is a protein that binds oxygen more

tightly than hemoglobin does

Page 50: OHHS AP Biology Chapter 50 (Class Presentation)

• Glycolytic fibers use glycolysis as their primary source of ATP

• Glycolytic fibers have less myoglobin than oxidative fibers, and tire more easily

• In poultry and fish, light meat is composed of glycolytic fibers, while dark meat is composed of oxidative fibers

Page 51: OHHS AP Biology Chapter 50 (Class Presentation)

Fast-Twitch and Slow-Twitch Fibers• Slow-twitch fibers contract more slowly, but

sustain longer contractions• All slow twitch fibers are oxidative• Fast-twitch fibers contract more rapidly, but

sustain shorter contractions• Fast-twitch fibers can be either glycolytic or

oxidative

Page 52: OHHS AP Biology Chapter 50 (Class Presentation)

• Most skeletal muscles contain both slow-twitch and fast-twitch muscles in varying ratios