Exam 1 (ch 15-17)

Question 1

Which senses are the general senses?

Answer 1

General senses include sensitivity to touch, temperature, pain, pressure, vibration, and body position.

Question 2

Define the Law of Specific Nerve Energies and give an example.

Answer 2

The law states that the mind has access not to objects in the world but only to our nerves & implies that the contents of the mind have no qualities in common with environmental objects but serve only as arbitrary signs or markers of those objects.

Question 3

Define Phasic versus Tonic Receptors, Give examples of each.

Answer 3

Tonic receptors are sensory neurons that are always active and determine an increase or decrease in stimulation while Phasic receptors are usually not active and provide information about the intensity and change of a stimulus.

Question 4

List and define the first and second classification schemes for the general senses

Answer 4

First classification: Exteroceptors (external environment), Proprioceptors (positions of skeletal muscles), & interoceptors (monitor visceral organs)
Second classification: nociceptors (pain), thermoreceptors (temperature), mechanoreceptors (physical distortion or touch), & chemoreceptors (chemical concentration)

Question 5

Define Lateral Inhibition

Answer 5

lateral inhibition is the ability of excited neurons to inhibit the activity of neighboring neurons. This prevents the spread of neuronal activity laterally. Receptors that are most strongly stimulated inhibit those around them.

Question 6

What are receptive fields and how do they relate to sense acuity?

Answer 6

The smaller the receptive field is, the higher the density of sensory receptors, resulting in high acuity or sensitivity in that area.

Question 7

What is a nociceptor?

Answer 7

Nociceptors are pain receptors that are especially common superficial portions of the skin, joint capsules, and around walls of blood vessels.
Stimulation of the dendrites of a nociceptor causes depolarization.

Question 8

Identify reasons for slow and fast pain.

Answer 8

Myelinated Type A fibers carry sensations of fast pain, like you would feel from a deep cut. This is because these sensations reach the CNS quickly and trigger somatic reflexes that are also relayed to the primary somatosensory cortex
Unmyelinated Type C fibers carry sensations of slow pain, or burning and aching pain. These sensations cause a generalized activation of the reticular formation and thalamus. You become aware of the pain but only have a general idea of the area affected.

Question 9

Define referred pain and identify regions of specific referred pain.

Answer 9

Referred pain is pain sensations from visceral organs that are perceived as arising from different areas of the body. This occurs because the body surface is innervated by the same spinal segments.
Shoulder- gallbladder, down forearm-heart, lower stomach-colon, sides of lower torso- ureters (UTI)

Question 10

Know different types of thermoreceptors

Answer 10

Cold- many more receptors that respond to cold than hot, located close to epidermis, stimulated by cold & inhibited by warm
Warm- located deeper in the dermis, excited by warming & inhibited by cooling, different from receptors that detect heat
Hot- pain experienced by a hot stimulus is sensed by a nociceptor (capsaicin receptor), serves as an ion channel for sodium and calcium

Question 11

Know the different mechanoreceptors of the skin, internal organs, joints and muscles.

Answer 11

Tactile receptors- touch & skin
Baroreceptor- internal organs
Proprioceptor- joints and muscles

Question 12

Where do we have chemoreceptors? What do they detect?

Answer 12

Chemoreceptors are also located in the carotid bodies, near the origin of the internal carotid arteries on each side of the neck, and in the aortic bodies, between the major branches of the aortic arch. (The carotid bodies and aortic bodies are small tissue masses of receptors and supporting cells.) These receptors monitor the pH and the carbon dioxide and oxygen levels in arterial blood and play an important role in the reflexive control of breathing and cardiovascular function.

Question 13

Compare and contrast the SNS and ANS?

Answer 13

The SNS and ANS are very different. The SNS consists of motor neurons that work to stimulate the skeletal muscles. However, in the ANS, motor neurons work to control smooth and cardiac muscle along with glands in the body.

Question 14

Define preganglionic and ganglionic neurons. How do they differ from preganglionic and postganglionic fibers?

Answer 14

Preganglionic neurons are cell bodies that lie within the lateral gray column of the spinal cord running from T1 to L2 which travel to the ganglia where they synapse and activate nicotinic receptors using acetylcholine. Ganglionic neurons release acetylcholine at the synapse of the ganglion and release information. Preganglionic fibers are relatively short because the ganglia are located relatively near the spinal cord (sympathetic division) while postganglionic fibers are relatively long as they travel to the target organ.

Question 15

What are 2 subdivisions of the ANS? Briefly describe where the preganglionic fibers originate, the names of the ganglia they may synapse in.

Answer 15

The two subdivisions of the ANS are sympathetic and parasympathetic. In the sympathetic division, the preganglionic fibers originate closer to the spinal cord, making them relatively short. They may synapse in the celiac ganglion, superior mesenteric ganglion, inferior mesenteric ganglion, or collateral ganglia which lie along the vertebrae. In the parasympathetic division, the preganglionic fibers are relatively long (located in the craniosacral region of the spinal cord) as the ganglia lie either within or near the target organ. They may synapse in the pterygopalatine ganglion, ciliary ganglion, submandibular ganglion, or the otic ganglion.

Question 16

List 2 general statements about the synapses and neurotransmitters in the ANS.

Answer 16

Changes in visceral activity take place in response to neurotransmitters released by neurons of the ANS. Motor neurons of the CNS synapse on visceral motor neurons in autonomic ganglia (clusters of nerve cell bodies in the ANS), and these ganglionic neurons control visceral effectors.

Question 17

List and briefly describe the 3 major components of the sympathetic division (be able to label 16.2

Answer 17

Short preganglionic fibers: located in thoracic and lumbar regions of the spinal cord (thoracolumbar region T1-L2). Cell bodies of preganglionic neurons located in lateral horns & their axons enter the anterior roots of theses segments
Ganglionic neurons in ganglia near spinal cord: the preganglionic fibers are relatively short in this division because ganglia are located near the spinal cord. They release ACh which stimulate the ganglionic neurons.
Long postganglionic fibers to target organs: postganglionic fibers are relatively long as they travel from the ganglia near the spinal cord to the target organs.

Question 18

Describe sympathetic ganglia chain

Answer 18

Sympathetic chain ganglia lie on each side of the vertebral column. Neurons in these ganglia control the body wall, limbs, head, and neck. Some functions include:
Reduction of circulation to the skin
More circulation to skeletal muscles
Stimulation of arrector pili muscles
Increased heart rate

Question 19

Describe collateral ganglia.

Answer 19

Collateral ganglia lie anterior to the vertebral column and contain ganglionic neurons that innervate the abdominopelvic tissues and viscera.

Question 20

How is the suprarenal medulla innervated by the sympathetic division?

Answer 20

The center of each adrenal gland (adrenal medulla) is a modified sympathetic ganglion. Ganglionic neurons of the adrenal medulla have very short axons which secrete neurotransmitters right into the bloodstream (not at a synapse). This allows the neurotransmitters to act as hormones for target organs.

Question 21

Describe types of sympathetic synapses and their neurotransmitter release.

Answer 21

sympathetic preganglionic neurons release acetylcholine (ACh) at synapses with ganglionic neurons.
Most sympathetic ganglionic neurons release norepinephrine (NE) at their varicosities. Neurons that release NE are called adrenergic
NE stimulates alpha receptors to a greater degree than it does beta receptors, and E stimulates both classes of receptors. For this reason, localized sympathetic activity, involving the release of NE at varicosities, primarily affects nearby alpha receptors

Question 22

List and briefly describe the 2 major components of parasympathetic division.

Answer 22

-Long pregranglionic fibers in the brainstem and sacral segments in the spinal cord: All parts of the brainstem, the midbrain, pons, and medulla oblongata, contain autonomic nuclei associated with several cranial nerves. In sacral segments of the spinal cord, the parasympathetic nuclei lie in the lateral horns of spinal segments S2–S4 (craniosacral division)
-Ganglionic Neurons in Peripheral Ganglia within or Adjacent to Target Organs: Preganglionic fibers of the parasympathetic division do not diverge as extensively as do those of the sympathetic division. A typical preganglionic fiber synapses on six to eight ganglionic neurons, all in the same ganglion. The ganglion may be a terminal ganglion, located near the target organ, or an intramural (murus, wall) ganglion, embedded in the tissues of the target organ

Question 23

Describe parasympathetic ganglia.

Answer 23

Parasympathetic preganglionic fibers leave the brain in cranial nerves III (oculomotor), VII (facial), IX (glossopharyngeal), and X (vagus). These fibers carry the cranial parasympathetic output to visceral structures in the head. These fibers synapse in the ciliary, pterygopalatine, submandibular, and otic ganglia.
These ganglia are typically near the target organ or embedded in the tissue of the target organ (intramural)

Question 24

Describe the types of parasympathetic synapses and their neurotransmitter release

Answer 24

All parasympathetic neurons release ACh as a neurotransmitter.
Nicotinic receptors occur on ganglion cells of both the parasympathetic and sympathetic divisions. (They also occur at neuromuscular junctions of the somatic nervous system.) When ACh activates nicotinic receptors, it opens chemically gated Na+ channels in the postsynaptic membrane of the ganglionic neuron or motor end plate of the muscle fiber, which always causes excitation of that cell.
Muscarinic receptors occur at cholinergic neuromuscular or neuroglandular junctions in the parasympathetic division. They also occur at the few cholinergic junctions in the sympathetic division. Muscarinic receptors are G protein–coupled receptors. Their stimulation and G protein activation produce longer-lasting effects than does the stimulation of nicotinic receptors.

Question 25

Please explain what is meant by the term dual innervation in the ANS.

Answer 25

When vital organs receive instructions from both divisions. Where dual innervation exists, the two divisions commonly have opposing effects. Dual innervation with opposing effects is most obvious in the digestive tract, heart, and lungs. At other sites, the responses may be separate or complementary.

Question 26

What structures are responsible for Gustation?

Answer 26

The tongue and its taste buds and papillae are responsible for gustation.

Question 27

Describe Gustation Pathways. Include Cranial Nerve.

Answer 27

The Gustatory pathway starts with the taste buds (innervated by cranial nerves VII (facial), IX (glossopharyngeal), and X (vagus)). The sensory afferent fibers carried by these cranial nerves synapse in the solitary nucleus of the medulla oblongata. Then, the axons of the postsynaptic neurons will enter the medial lemniscus where the neurons join axons that carry somatic sensory information on touch, pressure, and proprioception. After another synapse in the thalamus, the information is sent to the appropriate portions of the gustatory cortex of the insula.

Question 28

Describe different types of papillae. Where are they located on the tongue?

Answer 28

Filiform papillae: found in the anterior two-thirds of the tongue running parallel to the midline groove. They do not contain taste buds, but they do provide an abrasive coat that creates friction to help move food around the mouth
Fungiform papillae: scattered around the tongue with concentration along the tip and sides. Each small fungiform papilla contains about 5 taste buds.
Vallate papillae: appear as an inverted “V” near the posterior margin of the tongue. There are up to 12 vallate papillae, and each contains as many as 100 taste buds
Foliate papillae: The foliate papillae are found as a series of folds along the lateral margins with taste buds embedded in their surfaces.

Question 29

What regions of the tongue are associated with different taste sensations?

Answer 29

Sweet, salty, and sour have been found to be the most sensitive on the axis of the tongue
Taste buds in all portions of the tongue provide all four primary taste sensations.

Question 30

Know what ions stimulate the different taste sensations.

Answer 30

The best-known example involves sensitivity to the compound phenylthiocarbamide (PTC). This substance tastes bitter to some people, but is tasteless to others

Question 31

What structures are responsible for Olfaction?

Answer 31

Olfactory organs are made up of two layers: olfactory epithelium and lamina propria.
The olfactory epithelium contains the olfactory sensory neurons, supporting cells, and regenerative basal epithelial cells (stem).
The lamina propria consists of areolar tissue, numerous blood vessels, and nerves. This layer also contains olfactory glands. Their secretions absorb water and form thick, pigmented mucus.

Question 32

Describe olfactory pathways. Include Cranial Nerve.

Answer 32

The olfactory pathway begins with afferent fibers leaving the olfactory epithelium that collect into 20 or more bundles. These bundles penetrate the cribriform plate of the ethmoid bone to reach the olfactory bulbs of the cerebrum, where the first synapse occurs. Efferent fibers from nuclei elsewhere in the brain also innervate neurons of the olfactory bulbs. Axons leaving the olfactory bulb travel along the olfactory tract to the olfactory cortex of the cerebral hemispheres, the hypothalamus, and portions of the limbic system.
Olfactory Nerve (CN1)

Question 33

What other system is the location connected to and what does that system do?

Answer 33

Olfaction is closely connected to Gustation
both involve molecules of the stimulus entering the body and bonding to receptors

Question 34

Describe three general areas of the eye and identify key structures in each

Answer 34

Outer fibrous layer: contains sclera & cornea (protects and supports the eye)
Vascular Layer: contains iris, ciliary body, & choroid (provides a route for blood vessels and lymphatics that supply the tissues of the eye; regulates the amount of light that enters the eye; secretes and reabsorbs the aqueous humor that circulates within the chambers of the eye; and controls the shape of the lens),
Deep inner layer (retina): contains retina (consists of a thin lining called the pigmented layer, and a thicker covering called the neural layer) (two layers of the retina are normally very close together, but not tightly interconnected. The pigmented layer of the retina continues over the ciliary body and iris, but the neural layer extends anteriorly only as far as the ora serrata. The neural layer of the retina forms a cup that establishes the posterior and lateral boundaries of the posterior cavity)

Question 35

What structures are responsible for Equilibrium?

Answer 35

The semicircular canals, the utricle, and the saccule of the inner ear.

Question 36

Describe the Vestibular Complex and types of receptors responsible for equilibrium. Describe the receptors and types of sensation detected.

Answer 36

Receptors of the Vestibular Complex are what provide you with equilibrium sensations.
These receptors are hair cells. They are located in the semicircular duct, saccule and utricle of the vestibule
The hair cells in the Semicircular duct convey information about rotational movements of the head. Hair cells in the saccule & utricle convey information about your position with respect to gravity & whether you are accelerating or decelerating.
Each semicircular duct contains an ampulla (expanded region that contains these receptors)

Question 37

Describe the equilibrium pathways. Include Cranial Nerves

Answer 37

The reflexive motor commands issued by the vestibular nuclei are distributed to the motor nuclei for cranial nerves involved with eye, head, and neck movements (CN III, IV, VI, and XI).

Question 38

What structures are responsible for hearing?

Answer 38

The receptors of the cochlear duct provide a sense of hearing.
in the process of hearing, arriving sound waves are converted into mechanical movements by vibration of the tympanic membrane. These vibrations are then conducted to the internal ear by the auditory ossicles. In the internal ear, the vibrations are converted to pressure waves in fluid, which eventually are detected by the hair cells in the cochlear duct. This sensory information is sent to the auditory cortex of the brain to be interpreted.

Question 39

Describe the cochlea and receptors responsible for hearing.

Answer 39

the cochlear duct, or scala media, lies between a pair of perilymphatic chambers, or scalae: the scala vestibuli, or vestibular duct, and the scala tympani, or tympanic duct. The outer surfaces of all three ducts are encased by the bony labyrinth everywhere except at the oval window (the base of the scala vestibuli) and the round window (the base of the scala tympani).

Question 40

Describe auditory pathways. Include Cranial Nerves

Answer 40

Stimulation of hair cells along the basilar membrane activates sensory neurons whose cell bodies are in the adjacent spiral ganglion . The afferent fibers of those neurons form the cochlear nerve.
These axons enter the medulla oblongata, where they synapse at the cochlear nucleus on that side..
From there, information ascends to both superior olivary nuclei of the pons and both inferior colliculi of the midbrain .
This midbrain processing center coordinates a variety of unconscious motor responses to acoustic stimuli, including auditory reflexes that involve skeletal muscles of the head, face, and trunk . These reflexes automatically change the position of your head in response to a sudden loud noise.

Question 41

List and describe the accessory structures of the eye.

Answer 41

Palpebrae (eyelids): continuation of skin, continual blinking keeps the surface of the eye lubricated, they also clean and protect the eye
Palpebral fissure: gap that separates 3 margins of the upper and lower eyelids
medial/lateral canthus: where the two eyelids connect
Eyelashes: associated with unusually large sebaceous gland
Tarsal glands: secrete a lipid-rich substance that helps keep the eyelids from sticking together
Lacrimal apparatus: produces, distributes, and removes tears
Conjunctiva: epithelium covering the inner surfaces of the eyelids and the outer surface of the eyeball
Lacrimal caruncle glands: lacrimal lake (tears settled in medial canthus), covers the lacrimal caruncle, which bulges anteriorly.. They empty into the lacrimal canaliculi, small canals that in turn lead to the lacrimal sac, which nestles within the lacrimal sulcus of the orbit

Question 42

What are the two layers of the conjunctiva?

Answer 42

Palpebral conjunctiva- covers inner surface of the eyelids
Bulbar conjunctiva- covers anterior surface of the eye

Question 43

What is the difference between a sty and a cyst?

Answer 43

Cysts result from an infection of the tarsal gland while a sty is a painful swelling from an infection in a sebaceous gland associated with an eyelash

Question 44

Describe the lacrimal apparatus

Answer 44

The lacrimal apparatus produces, distributes, and removes tears. The lacrimal apparatus of each eye consists of (1) a lacrimal gland with associated ducts, (2) paired lacrimal canaliculi, (3) a lacrimal sac, and (4) a nasolacrimal duct

Question 45

Describe general structures of the eye

Answer 45

the eyeball shares space with the extrinsic eye muscles, the lacrimal gland, and the cranial nerves and blood vessels that supply the eye and adjacent portions of the orbit and face. Orbital fat cushions and insulates the eye.

Question 46

Describe the 3 layers (tunics of the eye)

Answer 46

the fibrous layer- the outermost layer of the eyeball, consists of the whitish sclera & cornea & supports and protects the eye, serves as an attachment site for the extrinsic eye muscles, and contains structures that assist in focusing.
The vascular layer- pigmented region that includes the iris, ciliary body, and choroid & contains numerous blood vessels, lymphatic vessels, and the intrinsic (smooth) muscles of the eye. This middle layer provides a route for blood vessels and lymphatics that supply the tissues of the eye; regulates the amount of light that enters the eye; secretes and reabsorbs the aqueous humor that circulates within the chambers of the eye; and controls the shape of the lens, an essential part of the focusing process.
Retina- deepest of the three layers & consists of a thin lining called the pigmented layer, and a thicker, covering called the neural layer. The pigmented layer contains pigment cells that support the functions of the photoreceptors, which are located in the neural layer of the retina.

Question 47

Define aqueous and vitreous humors. Their function and location?

Answer 47

Aqueous humor - fluid that circulates within the anterior cavity & passes from the posterior chamber to the anterior chamber through the pupil & also freely diffuses through the posterior cavity and across the surface of the retina. Its composition resembles that of cerebrospinal fluid.
Vitreous Humor- liquid portion of the Vitreous body, located in the posterior cavity of the eye to help stabilize the shape of eye

Question 48

Define visual pathways. Include cranial nerve

Answer 48

The visual pathways begin at the photoreceptors and end at the visual cortex of the cerebral hemispheres. The message must cross two synapses (photoreceptor to bipolar cell, and bipolar cell to ganglion cell). Only then does it move toward the brain. The extra synapse increases the synaptic delay, but it provides an opportunity for the processing and integration of visual information before it leaves the retina.

Question 49

What causes glaucoma and detached retina?

Answer 49

The most common reason for a detached retina is when the neural layer of the retina becomes separated from the pigmented layer or leaking blood vessels or swelling in the back of the eye
Damage to the optic nerve causes glaucoma

Question 50

Know the differences between the fovea centralis and optic disc

Answer 50

Optic disc- a circular region just medial to the fovea centralis & is the origin of the optic nerve (II)
The highest concentration of cones occurs at the center of the macula, an area called the fovea centralis (fovea centralis is the site of sharpest color vision)

Question 51

Know the layers of the retina

Answer 51

Consists of a thin lining (pigmented layer) and a thicker covering (neural layer)
Pigmented layer contains pigment cells that support the functions of the photoreceptors, which are located in the neural layer of the retina. These two layers of the retina are normally very close together, but not tightly interconnected.

Question 52

Know the differences between rods and cones

Answer 52

Rods are photoreceptors responsible for vision in dim lighting while cones is the photoreceptor responsible for sharp vision and color vision

Question 53

What are the pigments responsible for vision?

Answer 53

rhodopsin

Question 54

What happens to the retina when light hits it?

Answer 54

Photoreceptors turn light into electrical signals

Question 55

What is dark adaptation?

Answer 55

The ability of your eyes to adjust from seeing in the light to seeing in the dark

Question 56

Describe what is happening to the photoreceptor cells, bipolar cells and ganglionic cells during dark current and when light is present

Answer 56

Rods and cones synapse with about 6 million neurons called bipolar cells. These cells in turn synapse within the layer of the 1 million neurons called ganglion cells, which lie adjacent to the posterior cavity. A network of horizontal cells extends across the neural layer of the retina at the level of the synapses between photoreceptors and bipolar cells. A comparable network of amacrine cells occurs where bipolar cells synapse with ganglion cells. Horizontal and amacrine cells can facilitate or inhibit communication between photoreceptors and ganglion cells, altering the sensitivity of the retina.
These cells play an important role in the eye’s adjustment to dim or brightly lit environments.

Question 57

What pigments are responsible for color vision?

Answer 57

whose color vision is based on sets of red-, green-, and blue-sensitive cones, each with a different visual pigment

Question 58

How do the arrangements of ganglionic cells to photoreceptor cells differ for sensitivity (rods) vs acuity (cones)

Answer 58

Rods and cones are not evenly distributed across the retina. Approximately 125 million rods form a broad band around the periphery of the retina. As you move toward the center of the retina, the density of rods gradually decreases. In contrast, most of the roughly 6 million cones are concentrated in the area where a visual image arrives after it passes through the cornea and lens