1.
What is the function of:
▪
Cone cells?
▪
Rod cells?
2.
The perceived pitch of a sound is
dependent on… ?
3.
What is the difference between
1.
What is the function of:
▪
Cone cells?
Color
▪
Rod cells?
Light
2.
The perceived pitch of a sound is
dependent on… ?
wavelength (
λ
)
1.
What is the difference between
Chapter 50
The location and function of several
types of sensory receptors
How skeletal muscles contract
Cellular events that lead to muscle
Mechanoreceptors
: physical stimuli –
pressure, touch, stretch, motion, sound
Thermoreceptors
: detect heat/cold
Chemoreceptors
: transmit solute conc.
info – taste (gustatory), smell (olfactory)
Electromagnetic receptors
: detect EM
energy – light (photoreceptors),
electricity, magnetism
Pain receptors
: respond to excess heat,
This rattlesnake and other pit vipers have a pair of infrared receptors, one between each eye and nostril. The organs are sensitive enough to detect the infrared radiation emitted by a warm mouse a meter away.
Eye Infrared receptor
Some migrating animals, such as these beluga whales, apparently sense Earth’s magnetic field and use the information, along with other cues, for orientation.
Reception
Reception
: receptor detects a
stimulus
Sensation = action potentials reach
Sensation
brain via sensory neurons
Perception
Perception
: information processed
Outer ear Middleear Inner ear Pinna Auditory canal Tympanic membrane Eustachian tube Middle ear Stapes Incus Malleus Skull bones Semicircular canals Auditory nerve, to brain Tympanic membrane Oval window Round window Cochlea Eustachian tube Auditory nerve Tympanic canal Cochlea duct
Organ of Corti Vestibular canal Bone To auditory nerve Axons of sensory neurons Basilar membrane Hair cells Tectorial membrane
Semicircular canals
Flow
of endolymph
Vestibular nerve
Nerve fibers Vestibule
Utricle Saccule
Ampulla
Flow
of endolymph
Cupula
Body movement
Hairs Hair cell
Cornea
Ciliary body
Suspensory
ligament
Iris
Pupil
Aqueous
humor
Lens
Vitreous humor
Central artery and
vein of the retina
Optic disk
(blind spot)
Fovea (center
of visual field)
Optic
nerve
Retina
Choroid
Sclera
Compound eyes
: several
thousand ommatidia (light
detectors) with its own
lens;
insects & crustaceans
Vertebrates:
Rods
: sense light
Cones
: color vision
Rhodopsin
:
light-absorbing pigment that
triggers signal transduction
pathway that leads to sight
Retina Optic nerve To brain Cone Photoreceptors Retina Rod Neurons Pigmented epithelium Bipolar cell Amacrine cell Horizontal cell Optic nerve
Hydrostatic
: fluid held under
pressure in closed body compartment
Hydra, nematodes, annelids
Exoskeletons
: hard encasements on
surface of animal
Insects, mollusks, crustaceans
Endoskeleton
: hard supporting
elements buried within soft tissues
Shoulder girdle Scapula Clavicle Sternum Skull Appendicular skeleton Axial skeleton Key Rib Humerus Vertebra Radius Examples of joints Fibula Ulna Tibia Pelvic girdle Carpals Phalanges Metacarpals Femur Patella Tarsals Metatarsals Phalanges Ulna
Pivot joints allow us to rotate our forearm at the elbow and to move our head from side to side. Ulna
Hinge joints, such as between the humerus and the head of the ulna, restrict movement to a single plane.
Humerus
Ball-and-socket joints, where the humerus contacts the shoulder girdle and where the femur contacts the pelvic girdle, enable us to rotate our arms and legs and move them in several planes. Head of
humerus Scapula
Biceps
contracts
Human
Triceps
relaxes
Forearm
flexes
Biceps
relaxes
Triceps
contracts
Forearm
extends
Extensor
muscle
relaxes
Flexor
muscle
contracts
Grasshopper
Extensor
muscle
contracts
Flexor
muscle
relaxes
Tibia
extends
Tibia
flexes
Muscles always
contract
Muscles work in
antagonistic pairs
Bundle of muscle fibers Single muscle fiber (cell) Plasma membrane Nuclei Muscle Myofibril Dark band Sarcomere Z line Light band I band TEM
A band I band0.5 µm M line
Thick filaments (myosin)
SarcomereH zone Z line
Thin filaments (actin)
Z line
Attached to bones by
tendons
Types of muscle:
smooth
(internal organs)
cardiac
(heart)
Skeletal
(striated)
1 long fiber = single muscle
cell
Each muscle fiber = bundle
of
myofibrils
, composed of:
▪
Actin: thin filaments
Sarcomere
0.5 µm
Z
H
A
Relaxed muscle fiber
I
Contracting muscle fiber
Fully contracted muscle fiber
Z lines
– border
I band
– thin actin filaments
Sarcomere
0.5 µm
Z
H
A
Relaxed muscle fiber
I
Contracting muscle fiber
Fully contracted muscle fiber
1.
Sarcomere relaxed: actin &
myosin overlap
2.
Contracting:
Muscle fiber stimulated by
motor neuron
motor neuron
Length of sarcomere is reduced
Actin slides over myosin
3.
Fully contracted: actin & myosin
completely overlap
Sliding-filament model
: thick &
thin filaments slide past each
other to increase overlap
Ca2+ released
from sarcoplasmic reticulum
Mitochondrion Motor
neuron axon
Synaptic terminal
T tubule
Sarcoplasmic reticulum
Myofibril
Plasma membrane of muscle fiber
Ca2+
CYTOSOL Ca2+
SR
PLASMA MEMBRANE T TUBULE
Synaptic cleft Synaptic terminal of motor neuron
Myosin-binding sites blocked.
Myosin-binding sites exposed.
Tropomyosin
Ca
2+-binding sites
Actin
Troponin complex
Myosin-binding site
Thin filaments
Thick filament
Thin filament
Thick filament Myosin head (low-energy configuration)
Cross-bridge binding site
Myosin head (high-energy configuration) Actin
Cross-bridge Myosin head
(low-energy configuration) Thin filament moves
toward center of sacomere.
