Download Essentials of Biology Sylvia S. Mader

Essentials of Biology
Sylvia S. Mader
Chapter 28
Lecture Outline
Prepared by: Dr. Stephen Ebbs
Southern Illinois University Carbondale
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
28.1 The Senses
• All living organisms respond to environmental
signals (stimuli).
• The stimuli are received by sense organs which
transmit a signal to the central nervous system.
• The central nervous system sends signals to
generate a motor response to the stimuli.
28.1 The Senses (cont.)
Chemical Senses
• Chemicals in the
environment are
detected with
chemoreceptors.
• Chemoreceptors are
found in different
places on different
organisms.
Taste and Smell
• An example of human chemoreceptors are the
taste buds on the tongue.
• There are four primary tastes.
–
–
–
–
Sweet
Sour
Bitter
Salty
• A particular food or chemical can stimulate more
than one type of taste bud.
Taste and Smell (cont.)
Hearing and Balance
• The ears provide two sensory functions.
– Hearing
– Balance and equilibrium
• The sensory receptors for these functions
are mechanoreceptors, dependent upon
mechanical stimulation.
Hearing
• The sound receptors in many animals involves a
tympanic membrane, which transmits sound
vibrations to the sensory receptors.
• In humans, the outer ear collects sounds,
transmit them through the tympanic membrane
and to the three bones of the inner ear.
• The hearing portion of the inner ear is the
cochlea, which contains sensory receptors
called the spiral organ.
Hearing (cont.)
Hearing (cont.)
Hearing (cont.)
• The spiral organ can distinguish between
the volume and pitch of sounds.
• Damage to ear structures can lead to
deafness.
– Damage to the middle ear produces
conduction deafness.
– Damage to the spiral organ produces nerve
deafness.
Balance
• There are two senses of balance.
– Rotational equilibrium, mediated by the
semicircular canals, provides balance in
three-dimensional space.
– Gravitational equilibrium, mediated by two
membranous sacs (the utricle and auricle),
provides balance with respect to gravity.
Similar Receptors in Other Animals
• Gravitational equilibrium in invertebrates is
provided by statocysts, which provides
information about the position of the head
relative to the body.
• The lateral line of fish senses changes in
water pressure and currents.
Similar Receptors in Other Animals
(cont.)
Similar Receptors in Other Animals
(cont.)
Vision
• Light is perceived by photoreceptors,
typically in the eyes of an organism.
– Compound eyes consist of several
independent visual units that each focus light
towards the photoreceptors.
– The camera-type eye has a single lens that
focuses light and images on photoreceptors.
• The photoreceptors of some organisms
can also perceive colors.
Vision (cont.)
The Human Eye
• The human eye is structured so that
external stimuli is prepared for the
photoreceptors in the retina.
– The cornea and lens focus light rays on the
photoreceptors.
– The iris uses the pupil to regulate the amount
of light that enters the eye.
The Human Eye (cont.)
Photoreceptors of the Eye
• There are two photoreceptors in the human eye.
– The cones, which provide color vision, are located in
the fovea of the retina.
– The rods, which are sensitive to light and provide
night vision, are scattered across the retina.
• The retina is composed of several cell layers
containing the photoreceptors and the sensory
neurons.
• The blind spot is the point where the optic nerve
is attached to the retina.
Photoreceptors of the Eye (cont.)
Photoreceptors of the Eye (cont.)
Cutaneous Receptors and
Proprioreceptors
• Cutaneous receptors are located in the
two layers of the skin.
– The epidermis of the skin contains receptors
for temperature and pain.
– The dermis of the skin has receptors for
pressure (Pacinian corpuscle) and touch.
• Proprioreceptors help maintain equilibrium
and posture.
Cutaneous Receptors and
Proprioceptors (cont.)
Cutaneous Receptors and
Proprioreceptors (cont.)
28.2 The Motor Systems
• The musculoskeletal system work together to
provide specific functions.
– Support and movement
– Protection of internal organs
– Support to other organ systems, such as the
respiratory and digestive systems
• The muscles and skeletal systems also have
individual functions.
– Skeletal muscles assist movement of the blood and
help maintain body temperature.
– Bones store fat and calcium.
28.2 The Motor Systems (cont.)
28.2 The Motor Systems (cont.)
• Other organisms in the animal kingdom
use a hydrostatic skeleton to provide
support and movement.
Axial and Appendicular Skeletons
• The axial skeleton has several bones.
– The skull, which is composed of the cranium and
facial bones.
– The vertebral column and the sacrum
– The rib cage and sternum
• The appendicular skeleton has several bones.
–
–
–
–
The shoulder girdle has the clavicle and scapula.
The pectoral girdle has coxal bones of the pelvis.
Arms consist of the humerus, ulna, and radius.
Legs consist of the femur, tibia, and fibula.
Structure of a Bone
• Bones are often comprised of more than one
type of bone tissue.
– Compact bone, which surrounds the central cavity of
long bones
– Spongy bone at each end of the bone has red bone
marrow
• Two cell types function in bones.
– Osteoblasts deposit bone.
– Osteoclasts liberate calcium from bone for release
into the bloodstream.
Structure of a Bone (cont.)
Skeletal Muscle and Physiology
• There are three types of muscle in the
human body, each with a different
structure.
– Cardiac muscle, found in the heart, consists
of striated, branched cells forming a lattice.
– Smooth muscle are long, spindle-shaped cells
that are formed in sheets.
– Skeletal muscle cells are elongated fibers
running the length of the muscle.
Skeletal Muscle and Physiology
(cont.)
Skeletal Muscle Contraction
• The contractile portion of a muscle fiber has
many parallel myofibrils.
• The striations of muscle fibers are caused by the
placement of protein filaments with contractile
units called sarcomeres comprised of actin and
myosin.
• The contraction of muscles is described by the
sliding filament model.
Skeletal Muscle Contraction (cont.)
Skeletal Muscle Contraction (cont.)
• In the presence of calcium, myosin binds to the actin
filaments.
• The myosin head flexes inward and backward, causing
the actin filament to shorten.
• In the presence of ATP, the myosin head detaches and
then reattaches at a new position on the actin filament.
• This cycle repeats to continue the shortening of the
muscle (contraction).
Muscles Move Bones at Joints
• Muscles generally work in antagonistic
pairs to provide movement.
• Muscles articulate movement at joints.
– Synovial joints have a fluid filled cavity that
ease friction as the bones move.
– Hinged joints move only in one direction.
– Ball-and-socket joints allow for rotational
movement.
Muscles Move Bones at Joints
(cont.)
Muscles Move Bones at Joints
(cont.)
Muscles Move Bones at Joints
(cont.)
• There are several joint disorders.
– Sprains occur when tendons or ligaments are
over-stretched at a joint.
– Bursitis is inflammation of a synovial joint.
– The cartilage that supports some joints can be
torn.
– Arthritis can occur when joints deteriorate.