Nervous System – Sensory Systems Biol 105 Lecture 11 Chapter 9

Copyright © 2009 Pearson Education, Inc. 1.Depolarization is caused by ______ ions entering or leaving (which one) the axon 1.The gap in between two neurons is called the ________. 2.What is the name for the chemicals that are held in vesicles and released from one neuron, and bind to receptors of the next neuron? 3.What part of the autonomic nervous system stimulates digestion? 4.What is the thin outer layer of the cerebrum where most of the higher thinking and processing takes place called 5.The part of the brain that processes sensory information (except smell) is called the ______. Concepts to Know:

Copyright © 2009 Pearson Education, Inc. Outline I.Senses II.Sensory receptors III.Touch IV.Vision V.Hearing and balance VI.Smell

Copyright © 2009 Pearson Education, Inc. Senses  Major senses – touch, hearing, smelling, taste, and seeing.  All the sensory nerves are routed through the thalamus except the nerves for smell.

Copyright © 2009 Pearson Education, Inc. Sensory receptor cells  Sensory receptors are specialized structures that detect stimuli (stimulus)  Sensory receptor cells change the stimulation into an electrical response that is transmitted through the nerves  If a sensory receptor is continuously stimulated, it will stop responding = sensory adaptation

12.2 The Central Nervous System 12-18

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Copyright © 2009 Pearson Education, Inc. Touch  We can sense different things through touch:  Thermal  Tactile  Pain  Vibration

Copyright © 2009 Pearson Education, Inc. Figure 9.2 Sense receptors of the skin

Copyright © 2009 Pearson Education, Inc. Figure 9.2 Sense receptors of the skin

Copyright © 2009 Pearson Education, Inc. Types of receptors in the skin  Free nerve endings  Merkel disks  Meissner’s corpuscles  Pacinian corpuscles  Ruffini corpuscles  Thermoreceptors

Copyright © 2009 Pearson Education, Inc. Free Nerve Endings  Free nerve endings – tips of dendrites of sensory neurons (free nerve endings may be wrapped around hair), detect touch and pain

Copyright © 2009 Pearson Education, Inc. Figure 9.2 Free nerve endings

Copyright © 2009 Pearson Education, Inc. Figure 9.2 Free nerve endings

Copyright © 2009 Pearson Education, Inc. Merkel Disks  Merkel disks – comprised of free nerve endings and Merkel cells, detect touch

Copyright © 2009 Pearson Education, Inc. Merkel disk

Copyright © 2009 Pearson Education, Inc. Meissner’s corpuscles  Meissner’s corpuscles – encapsulated nerve endings - detect light touch, tell us exactly where we were touched

Copyright © 2009 Pearson Education, Inc. Meissners corpuscle

Copyright © 2009 Pearson Education, Inc. Pacinian corpuscles  Pacinian corpuscles – layers of tissues surround the nerve ending, detects pressure when first applied, important in sensing vibration

Copyright © 2009 Pearson Education, Inc. Pacinian corpuscle

Copyright © 2009 Pearson Education, Inc. Ruffini corpuscles  Ruffini corpuscles – encapsulated nerve endings in deep layers that respond to continuous pressure

Copyright © 2009 Pearson Education, Inc. Ruffini corpuscle

Copyright © 2009 Pearson Education, Inc. Thermoreceptors  Thermoreceptors – specialized nerve endings, detects changes in temperature.

Copyright © 2009 Pearson Education, Inc. Vision  Sight is complex:  Light enters the eye, it is focused, then the light has to be transformed into it into an electrical signal that then has to be processed.

Copyright © 2009 Pearson Education, Inc. Vision  Light enters through the cornea  The lens focuses it to the back of the eye  The retina is a layer at the back of the eye where light is transformed into electrical signals

Copyright © 2009 Pearson Education, Inc. Figure 9.4 Retina FoveaOptic disk (blind spot) Optic nerve Choroid Sclera Vitreous humor (fills the posterior chamber) Iris Ciliary body Pupil Cornea Aqueous humor (fills the anterior chamber) Sclera Lens

Copyright © 2009 Pearson Education, Inc. Layers of the Eye – Outer layer  The sclera  Protects and shapes the eye  Provides attachment for muscles  The cornea  Allows light to enter

Copyright © 2009 Pearson Education, Inc. Outer Layer of Eye Table 9.1 (1 of 4)

Copyright © 2009 Pearson Education, Inc. Middle Layer of Eye  The choroid  Contains blood vessels that supply nutrients and oxygen.  Contains melanin, absorbs light reflected from the retina  The ciliary body  A ring of muscle that functions to focus the lens on the retina

Copyright © 2009 Pearson Education, Inc. Middle Layer of Eye  The iris  The colored portion of the eye  Contains smooth muscle that dilates or constricts to regulate the amount of light entering the eye  The pupil  The opening in the center of the iris that lets light into the eye

Copyright © 2009 Pearson Education, Inc. Middle Layer of the Eye Table 9.1 (2 of 4)

Copyright © 2009 Pearson Education, Inc. Inner Layer of Eye  Contains:  Retina  Photoreceptors - Rods and Cones  Fovea

Copyright © 2009 Pearson Education, Inc. Inner Layer of Eye - Retina  The retina contains photoreceptors  Rods  Cones – detect color  The fovea is a pit in the retina with a high concentration of cones

Copyright © 2009 Pearson Education, Inc. Vision Depends on the Eye Table 9.1 (3 of 4)

Copyright © 2009 Pearson Education, Inc. Structures of the Eye  Optic Nerve  Fluid  Aqueous humor  Vitreous humor  Lens

Copyright © 2009 Pearson Education, Inc. Optic Nerve  The optic nerve  Carries visual information to the brain  Forms a blind spot where it leaves the retina

Copyright © 2009 Pearson Education, Inc. Fluid in the Eye  There are two fluid filled chambers in the eye  Vitreous humor – jelly like fluid in posterior chamber. Holds retina against the wall of the eye  Aqueous humor – clear fluid in anterior chamber. Supplies nutrients and oxygen to cornea and lens, removes the waste. Creates pressure in eye to maintain shape of eye.

Copyright © 2009 Pearson Education, Inc. Lens  The lens can change shape to focus on near and far objects.  Focuses the light onto the retina  Ciliary muscles are attached to lens by ligaments

Copyright © 2009 Pearson Education, Inc. Vision Depends on the Eye Table 9.1 (4 of 4)

Copyright © 2009 Pearson Education, Inc. Photoreceptors  Cones and Rods have pigments that absorb  Cones work best in bright light and provide color vision  Rods work in low light situations but can only provide black and white vision

Copyright © 2009 Pearson Education, Inc. Photoreceptors  The photoreceptors (rods and cones) have pigments that absorb light  When there is no light coming in, they are releasing neurotransmitters (opposite of most receptors)  When they absorb light they stop releasing neurotransmitters

Copyright © 2009 Pearson Education, Inc. Photoreceptors  The neurotransmitters are inhibitory  When the neurotransmitters diminish, cells that process the information are stimulated  This information from these cells (bipolar and ganglion cells) is transmitted to the optic nerve to the thalamus to the visual cortex

Copyright © 2009 Pearson Education, Inc. Figure 9.8a (a) Light enters the left eye and strikes the retina. Light Retina Choroid Sclera Blind spot

Copyright © 2009 Pearson Education, Inc. Figure 9.8b Ganglion cell layer Bipolar cell layer Retina Photoreceptor cells Pigment layer Choroid Sclera Rod Electrical signals Axons Cone Light Vitreous humor

Copyright © 2009 Pearson Education, Inc. Figure 9.8c (c) The axons of the ganglion cells leave the eye at the blind spot, carrying nerve impulses to the brain (viewed from below) by means of the optic nerve. Retina Light Optic nerve Visual cortex

Copyright © 2009 Pearson Education, Inc. Rods and Cones Figure 9.9 (2 of 2) Rod cell Cone cell

Copyright © 2009 Pearson Education, Inc. Which part of the human eye detects colored light? 1.Pupil 2.Rods 3.Cones 4.Cornea

Copyright © 2009 Pearson Education, Inc. A ring of muscle that functions to focus the lens on the retina is the: 1.Iris 2.Choroid 3.Ciliary body 4.Sclera

Copyright © 2009 Pearson Education, Inc. Figure 9.10 A standard test for color blindness

Copyright © 2009 Pearson Education, Inc. Vision  Vision is much more complicated because these signals have to be processed into a 3-D image

Copyright © 2009 Pearson Education, Inc.

Hearing  Sound enters the ear canal and hits the tympanic membrane (ear drum).  The tympanic membrane vibrates.  This causes small bones in the ear to vibrate.  These bones focus and amplifies the vibrations onto a small place (oval window) on the cochlea.  The cochlea is a fluid filled coiled membrane.  The vibrations shakes the fluid in the cochlea

Copyright © 2009 Pearson Education, Inc. Three regions of the ear  Outer ear – the receiver  The middle ear – the amplifier  The inner ear – the transmitter

Copyright © 2009 Pearson Education, Inc. Three Regions of the Ear Figure 9.12 (1 of 2) Outer ear (receiver) Middle ear (amplifier) Inner ear (transmitter)

Copyright © 2009 Pearson Education, Inc. The Outer Ear  Consists of the:  Pinna – gathers the sound, acts like a funnel  External auditory canal – brings the sound from pinna to the tympanic membrane

Copyright © 2009 Pearson Education, Inc. Middle Ear  Consists of the:  The tympanic membrane separates the outer ear from the middle ear, vibrates when sound waves hit it.  Three auditory bones – amplify the vibration  Malleus  Incus  Stapes  Auditory tube (eustachian tube) – equalizes pressure between outer and middle ear

Copyright © 2009 Pearson Education, Inc. Middle Ear  The tympanic membrane vibrates when sound waves hit it and transmits the vibration to the malleus  The vibrations are amplified by the three bones and transmitted to the oval window

Copyright © 2009 Pearson Education, Inc. Parts of the Inner Ear  Oval window – transmits sound from the stapes to the fluid in the cochlea  Round window – relieves pressure  Cochlea – contains the receptor cells that transform the signal from vibration to an electrochemical signal to the neurons.  Vestibular apparatus – monitors position of the head

Copyright © 2009 Pearson Education, Inc. Hearing Depends on the Ear Figure 9.12 (2 of 2) The pinna gathers sound and funnels it into the external auditory canal to the tympanic membrane (eardrum). The eardrum vibrates synchronously with sound waves, causing the bones of the middle ear to move. The three bones of the middle ear amplify the pressure waves and convey the vibrations of the eardrum to the inner ear. The cochlea converts pressure waves to neural messages that are sent to the brain for interpretation as sound. Malleus (hammer) Incus (anvil) Stapes (stirrup) Semicircular canals Vestibular apparatus: Auditory nerve Cochlea Oval window Eardrum (tympanic membrane) Round window Auditory tube (Eustachian tube) Outer ear (receiver) Middle ear (amplifier) Inner ear (transmitter) External auditory canal Vestibule

Copyright © 2009 Pearson Education, Inc. Cochlea  It is in the cochlea where vibrations are transformed into electrical signals that can be sent by neurons  When the fluid in the cochlea moves, it moves small “hair cells” against a membrane. This allows ion channels to open  This leads to the release of neurotransmitters, which trigger the neuron to send the message

Copyright © 2009 Pearson Education, Inc. Hearing Depends on the Ear Figure 9.13 (1 of 2)

Copyright © 2009 Pearson Education, Inc. Hearing Depends on the Ear Figure 9.13 (2 of 2) Hair cell Tectorial membrane

Copyright © 2009 Pearson Education, Inc. In the ear, the fluid filled coiled membrane that is responsible transforming the vibrations into electrical signals. This structure is: 1.Tymphanic membrane 2.Staples 3.Cochlea 4.Incus

Copyright © 2009 Pearson Education, Inc. The tympanic membrane transmits the vibration to the ___.  Stapes  Malleus  Incus  Oval window

Copyright © 2009 Pearson Education, Inc. The Vestibular Apparatus  Balance depends on the vestibular apparatus of the inner ear  The vestibular apparatus is a fluid-filled maze of chambers and canals within the inner ear

Copyright © 2009 Pearson Education, Inc. The Vestibular Apparatus - Dynamic equilibrium  Fluid filled cupulas at base of the semicircular canals have hair cells that are stimulated when head moves. Hair cells send message to the brain.

Copyright © 2009 Pearson Education, Inc. The Vestibular Apparatus - Static equilibrium  Otoliths are small chalk like granules  When head is tilted the otoliths move and stimulate hair cells that send message to the brain

Copyright © 2009 Pearson Education, Inc. Balance Depends on the Vestibular Apparatus Figure 9.16a (1 of 2)

Copyright © 2009 Pearson Education, Inc. Balance Depends on the Vestibular Apparatus Figure 9.16a (2 of 2)

Copyright © 2009 Pearson Education, Inc. The Vestibular Apparatus Figure 9.16b (1 of 2)

Copyright © 2009 Pearson Education, Inc. The Vestibular Apparatus Figure 9.16b (2 of 2)

Copyright © 2009 Pearson Education, Inc. Smell - olfaction  Sensory nerves for smell go directly to the cerebral cortex and to the amygdala and the hypothalamus.  They do not pass through the thalamus

Copyright © 2009 Pearson Education, Inc. Smell - olfaction  Odor molecules bind to the receptors in the cilia of olfactory receptor cells  The receptor cells send the message to the neurons in the olfactory bulb which carry the message to the brain.

Copyright © 2009 Pearson Education, Inc. Figure 9.17 Sense of Smell

Copyright © 2009 Pearson Education, Inc. Figure 9.17 Sense of Smell

Copyright © 2009 Pearson Education, Inc. Taste  Taste and smell is very connected.  The tongue has taste buds on them  The taste buds have taste cells (receptor cells) in them

Copyright © 2009 Pearson Education, Inc. Taste  Food molecules bind to taste cells and stimulate them. The taste cells send the messages to the sensory neurons which send the message to the brain.

Copyright © 2009 Pearson Education, Inc. Smell and Taste Figure 9.18

Copyright © 2009 Pearson Education, Inc.  Read Chapter 6  What is the function of sensory receptor cells?  What is an example of sensory adaptation?  What are the types of senses of touch?  What are the types of sensory receptors in skin, what type of touch do they detect, be able to describe them? Important Concepts

Copyright © 2009 Pearson Education, Inc.  What are all of the layers and structures (including the fluids) of the eye and what are their functions?  What is the blind spot?  How does the signal travel from the photoreceptors to the brain, what part of the brain receives the signal? Be able to describe in detail this process, including the cells that transmit the messages. Important Concepts

Copyright © 2009 Pearson Education, Inc.  What are all the parts of the ear, are they part of the inner, middle or outer ear, and what is their functions? What is the path of sound waves and vibrations through the ear  How does the ear detect head movement and position?  How do we detect odor? What part of the brain receives the signal? Where are olfactory receptors found?  How do we detect tastes? What structures are responsible for taste? Important Concepts

Copyright © 2009 Pearson Education, Inc. Definitions stimuli (stimulus), sensory adaptation, dilates, constrict, bipolar cells, ganglion cells, photoreceptors, transmits, amplifies, otoliths, cupula, taste buds,