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Chapter 49. Sensory and Motor Mechanisms. Types of Sensory Receptors. Mechanoreceptors Chemoreceptors Electromagnetic receptors Thermoreceptors Pain receptors. Hair. Cold. Gentle touch. Pain. Heat. Epidermis.

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Presentation Transcript
chapter 49

Chapter 49

Sensory and Motor Mechanisms

types of sensory receptors
Types of Sensory Receptors
  • Mechanoreceptors
  • Chemoreceptors
  • Electromagnetic receptors
  • Thermoreceptors
  • Pain receptors
slide3

Hair

Cold

Gentletouch

Pain

Heat

Epidermis

Mechanoreceptors- sense physical deformation caused by stimuli such as pressure, stretch, motion, and sound

Dermis

Hypodermis

Hairmovement

Connectivetissue

Strongpressure

Nerve

chemoreceptors
Chemoreceptors
  • Generalchemoreceptorstransmit information about the total solute concentration of a solution
  • Specific chemoreceptors respond to individual kinds of molecules
slide5

Electromagnetic Receptors- detect electromagnetic energy such as light, electricity, and magnetism

Eye

Infraredreceptor

(a) Rattlesnake

(b) Beluga whales

thermoreceptors pain receptors
Thermoreceptors, Pain Receptors
  • Thermoreceptors- respond to heat or cold
  • Pain Receptors- respond to excess heat, pressure, or chemicals released from damaged or inflamed tissues
slide7

Middleear

Outer ear

Inner ear

Stapes

Skullbone

Semicircularcanals

Incus

Malleus

Auditory nerveto brain

Cochlea

Ovalwindow

Eustachiantube

Pinna

Auditorycanal

Roundwindow

Tympanicmembrane

hearing
Hearing
  • Vibrating objects create percussion waves in the air that cause the tympanic membrane to vibrate
  • Hearing is the perception of sound in the brain from the vibration of air waves
  • The three bones of the middle ear transmit the vibrations of moving air to the oval window on the cochlea
slide9
These vibrations create pressure waves in the fluid in the cochlea that travel through the vestibular canal
  • Pressure waves in the canal cause the basilar membrane to vibrate, bending its hair cells
  • This bending of hair cells depolarizes the membranes of mechanoreceptors and sends action potentials to the brain via the auditory nerve
slide10

Axons ofsensory neurons

Apex

Ovalwindow

Vestibularcanal

Stapes

Vibration

Basilar membrane

Tympaniccanal

Base

Fluid(perilymph)

Roundwindow

slide11

500 Hz(low pitch)

1 kHz

Flexible end ofbasilar membrane

Apex

2 kHz

Basilar membrane

4 kHz

8 kHz

Base(stiff)

16 kHz(high pitch)

taste
Taste

Sugar molecule

G protein

Sweetreceptor

Tongue

Phospholipase C

SENSORYRECEPTORCELL

Sugarmolecule

Receptor cells for taste are modified epithelial cells organized into taste buds

Five taste perceptions: sweet, sour, salty, bitter, and umami (elicited by glutamate)

Taste pore

PIP2

Sensoryreceptorcells

Tastebud

IP3(secondmessenger)

Sodiumchannel

Sensoryneuron

IP3-gatedcalciumchannel

Nucleus

ER

Ca2+(secondmessenger)

Na+

smell
Smell
  • Olfactory receptor cells are neurons that line the upper portion of the nasal cavity
  • Binding of odorant molecules to receptors triggers a signal transduction pathway, sending action potentials to the brain
slide14

Brain

Action potentials

Olfactorybulb

Odorants

Nasal cavity

Bone

Epithelialcell

Odorantreceptors

Chemo-receptor

Plasmamembrane

Cilia

Odorants

Mucus

vision
Vision
  • Iris: regulates the size of the pupil
  • Retina: contains photoreceptors
  • Lens: focuses light on the retina
  • Optic disk: a blind spot in the retina where the optic nerve attaches to the eye
slide16
Light is focused by changing the shape of the lens
  • The retina contains two types of photoreceptors: rods and cones
    • Rods are light-sensitive but don’t distinguish colors
    • Cones distinguish colors but are not as sensitive to light
slide17

Sclera

Choroid

Retina

Ciliary body

Suspensoryligament

Fovea (centerof visual field)

Cornea

Iris

Opticnerve

Pupil

Aqueoushumor

Lens

Central artery andvein of the retina

Vitreous humor

Optic disk(blind spot)

Animation: Near and Distance Vision

slide18

Rightvisualfield

Opticchiasm

Righteye

Lefteye

Leftvisualfield

Optic nerve

Primaryvisual cortex

Lateralgeniculatenucleus

skeletal muscle
Skeletal Muscle
  • Characterized by a hierarchy of smaller and smaller units
  • A skeletal muscle consists of a bundle of long fibers, each a single cell, running parallel to the length of the muscle
slide20
Each muscle fiber is itself a bundle of smaller myofibrils arranged longitudinally
  • The myofibrils are composed to two kinds of myofilaments:
    • Thin filaments consist of two strands of actin and one of regulatory protein
    • Thick filaments are staggered arrays of myosin molecules
slide21
Striated muscle- the regular arrangement of myofilaments creates a pattern of light and dark bands
  • Sarcomere- the functional unit of a muscle, separated by Z lines
slide22

Muscle

Bundle ofmuscle fibers

Nuclei

Single muscle fiber(cell)

Plasma membrane

Myofibril

Z lines

Sarcomere

slide23

TEM

0.5 µm

M line

Thickfilaments(myosin)

Thinfilaments(actin)

Z line

Z line

Sarcomere

the sliding filament model of muscle contraction
The Sliding-Filament Model of Muscle Contraction
  • Filaments slide past each other longitudinally, producing more overlap between thin and thick filaments
slide25

Sarcomere

0.5 µm

M

Z

Z

Relaxedmuscle

Contractingmuscle

Fully contractedmuscle

ContractedSarcomere

types of skeletal muscle fibers
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
slide27
Oxidative fibers- rely on aerobic respiration to generate ATP
  • Many mitochondria, a rich blood supply, and much myoglobin
  • Myoglobinis a protein that binds oxygen more tightly than hemoglobin does

Glycolytic fibers- use glycolysis as their primary source of ATP

  • 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

slide28
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

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

skeletal systems transform muscle contraction into locomotion
Skeletal systems transform muscle contraction into locomotion
  • Skeletal muscles are attached in antagonistic pairs, with each member of the pair working against the other
slide30

Human

Grasshopper

Extensormusclerelaxes

Bicepscontracts

Tibiaflexes

Flexormusclecontracts

Forearmflexes

Tricepsrelaxes

Bicepsrelaxes

Extensormusclecontracts

Tibiaextends

Forearmextends

Flexormusclerelaxes

Tricepscontracts

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