Topic 5.3: The Nervous System and the Senses

Question 1

Identify the three classes of neurons and describe their relationship to each other.

Answer 1

The three classes of neurons are sensory neurons, which take messages to the CNS; interneurons, which sum up messages from sensory neurons and other interneurons and communicate with motor neurons which take messages away from the CNS to effector organs, muscles, or glands.

Question 2

Describe the three parts of a neuron.

Answer 2

Most neurons contain dendrites, a cell body, and an axon.

Question 3

Distinguish the cell types that form the melin in the PNS versus the CNS.

Answer 3

Myelin is formed by Schwann cells in the PNS, and by oligodendrocytes in the CNS.

Question 4

Review the structure of gray matter and white matter, and describe where each is found in the CNS and PNS.

Answer 4

Gray matter contains nonmyelinated nerve fibers. In white matter, the fibers are myelinated. The brain has gray matter on the surface and white matter in deeper tissue. That pattern is reverse in the spinal cord.

Question 5

Define nervous system.

Answer 5

Organ system of humans that includes the brain, spinal cord, sense organs (eyes, ears, etc.), and associated nerves. Receives, integrates, and stores sensory input; coordinates activity of other organ systems.

Question 6

Define central nervous system (CNS)

Answer 6

Portion of the nervous system consisting of the brain and spinal cord.

Question 7

Define the peripheral nervous system (PNS)

Answer 7

Nerves and ganglia that lie outside the central nervous system.

Question 8

Define neurons

Answer 8

Nerve cell that characteristically has three parts: dendrites, cell body, and an axon.

Question 9

Define neuroglia

Answer 9

Nonconducting nerve cells that are intimately associated with neurons and that function in a supportive capacity.

Question 10

Define sensory (afferent neuron)

Answer 10

Nerve cell that transmits nerve impulses to the central nervous system after a sensory receptor has been stimulated.

Question 11

Define interneuron

Answer 11

Neuron located within the central nervous system that conveys messages between parts of the central nervous system.

Question 12

Define motor (efferent neuron)

Answer 12

Nerve cell that conducts nerve impulses away from the central nervous system and innervates effectors (muscle and glands).

Question 13

Define cell body

Answer 13

Portion of a neuron that contains a nucleus and from which dendrites and an axon extend.

Question 14

Define dendrites

Answer 14

Part of a neuron that sends signals toward the cell body.

Question 15

Define axon

Answer 15

Elongated portion of a neuron that conducts nerve impulses, typically from the cell body to the synapse.

Question 16

Define myelin sheath

Answer 16

White, fatty material—derived from the membrane of neurolemmocytes—that forms a covering for nerve fibers.

Question 17

Define Schwann cell

Answer 17

Cell that surrounds a fiber of a peripheral nerve and forms the myelin sheath.

Question 18

Define nodes of Ranvier

Answer 18

Gaps in the myelin sheath around a nerve fiber.

Question 19

Define oligodendrocyte

Answer 19

Type of glial cell that forms myelin sheaths around neurons in the CNS.

Question 20

Define gray matter

Answer 20

Nonmyelinated axons and cell bodies in the central nervous system.

Question 21

Define white matter

Answer 21

Myelinated axons in the central nervous system.

Question 22

Define tracts

Answer 22

Bundle of myelinated axons in the central nervous system.

Question 23

Describe the activity of the sodium-potassium pump present in neurons.

Answer 23

The sodium-potassium pumps in neurons, are always transporting Na+ to the outside, and K= to the inside of the cell.

Question 24

Explain how the changes in Na+ and K+ ion concentrations that occur during and action potential are associated with depolarization and repolarization.

Answer 24

During an action potential, the Na+ gates open and Na+ enters the cell, causing a depolarization. Then, the Na+ gates close and the K+ gates open, causing a repolarization (even a slight hyperpolarization).

Question 25

Explain how the nerves impulse is transmitted across a synapse.

Answer 25

1. After an action potential arrives at an axon terminal, Ca2+ enters, and synaptic vesicles fuse with the presynaptic membrane.
2. Neurotransmitter molecules are released and bind to receptors on the postsynaptic membrane.
3. When an excitatory neurotransmitter binds to a receptor, Na+ diffuses into the postsynaptic neuron, and an action potential begins.

Question 26

Define refractory period, saltatory conduction, and synaptic integration.

Answer 26

After the action potential passes one part of an axon, the sodium gates in that part are unable to open for a period of time, called the refractory period. This prevents action potentials from moving backward. A node of Ranvier is a gap between Schwann cells that make up the myelin sheath of an axon of a PNS neuron. Saltatory conduction is the “jumping” of action potentials as they spread from node to node. Synaptic integration is the summing up of all incoming excitatory and inhibitory messages by a neuron.

Question 27

Define nerve impulse

Answer 27

Electrical signal that conveys information along the length of a neuron.

Question 28

Define resting potential

Answer 28

Membrane potential of an inactive neuron.

Question 29

Define sodium-potassium pump

Answer 29

Carrier protein in the plasma membrane that moves sodium ions out of, and potassium ions into, cells; important in the function of nerve and muscle cells in animals.

Question 30

Define action potential

Answer 30

Electrochemical changes that take place across the axon membrane; the nerve impulse.

Question 31

Define refractory period

Answer 31

Time following an action potential when a neuron is unable to conduct another nerve impulse.

Question 32

Define saltatory conduction

Answer 32

Movement of nerve impulses from one node to another along a myelinated axon.

Question 33

Define synapse

Answer 33

Junction between neurons consisting of the presynaptic (axon) membrane, the synaptic cleft, and the postsynaptic (usually dendrite) membrane.

Question 34

Define synaptic cleft

Answer 34

Small gap between presynaptic and postsynaptic cells of a synapse.

Question 35

Define neurotransmitters

Answer 35

Chemical stored at the ends of axons that is responsible for transmission across a synapse.

Question 36

Define integration

Answer 36

Summing up of excitatory and inhibitory signals by a neuron or by some part of the brain.

Question 37

Describe the interaction of the CNS and PNS.

Answer 37

The CNS is composed of the spinal cord and the brain. The PNS, which lies outside of the SNS, is composed of nerves and ganglia. Sensory fibers send information to the NS, and motor fibers conduct information away from the CNS to tissues and organs. Ganglia are areas of nerves that are collections of cell bodies.

Question 38

Summarize the functions of the spinal cord.

Answer 38

The spinal cord is structured so that the brain can communicate with the peripheral nerves. The communication involves sensory and motor functions.

Question 39

Identify the four major parts of the brain and describe the general functions of each.

Answer 39

Cerebrum: receives sensory information, integrates it, and commands voluntary motor responses. Diencephalon has two parts: hypothalamus serves as a link between the nervous and endocrine system, maintaining homeostasis; thalamus receives sensory inputs except for smell. Cerebellum: processes information about body position and maintains posture and balance. Brain stem: acts as a relay between the cerebrum and spinal cord or cerebellum; regulates breathing through the pons; regulates vital functions through the medulla oblongata; receives and sends signals between the higher brain centers and the spinal cord.

Question 40

Define meninges.

Answer 40

Protective membranous coverings around the central nervous system.

Question 41

Define cerebrospinal fluid

Answer 41

Fluid found in the ventricles of the brain, in the central canal of the spinal cord, and in association with the meninges.

Question 42

Define ventricles

Answer 42

Cavity in an organ, such as a lower chamber of the heart or the ventricles of the brain.

Question 43

Define spinal cord

Answer 43

In vertebrates, the nerve cord that is continuous with the base of the brain and housed within the vertebral column.

Question 44

Define the brain

Answer 44

Ganglionic mass at the anterior end of the nerve cord; in vertebrates, the brain is located in the cranial cavity of the skull.

Question 45

Define cerebrum

Answer 45

Largest part of the brain in mammals.

Question 46

Define cerebral hemispheres

Answer 46

Either of the two lobes of the cerebrum in vertebrates.

Question 47

Define cerebral cortex

Answer 47

Outer layer of cerebral hemispheres; receives sensory information and controls motor activities.

Question 48

Define basal nuclei

Answer 48

Subcortical nuclei deep within the white matter that serve as relay stations for motor impulses and produce dopamine to help control skeletal muscle activities.

Question 49

Define hypothalamus

Answer 49

In vertebrates, part of the brain that helps regulate the internal environment of the body—for example, heart rate, body temperature, and water balance.

Question 50

Define thalamus

Answer 50

In vertebrates, the portion of the diencephalon that passes on selected sensory information to the cerebrum.

Question 51

Define pineal gland

Answer 51

Gland—either at the skin surface (fish, amphibians) or in the third ventricle of the brain (mammals)—that produces melatonin.

Question 52

Define cerebellum

Answer 52

In terrestrial vertebrates, portion of the brain that coordinates skeletal muscles to produce smooth, graceful motions.

Question 53

Define brain stem

Answer 53

In mammals, portion of the brain consisting of the medulla oblongata, pons, and midbrain.

Question 54

Define midbrain

Answer 54

In mammals, the part of the brain located below the thalamus and above the pons.

Question 55

Define pons

Answer 55

Portion of the brain stem above the medulla oblongata and below the midbrain; assists the medulla oblongata in regulating the breathing rate.

Question 56

Define medulla oblongata

Answer 56

In vertebrates, part of the brain stem that is continuous with the spinal cord; controls heartbeat, blood pressure, breathing, and other vital functions.

Question 57

Define reticular activating system (RAS)

Answer 57

Area of the brain that contains the reticular formation; acts as a relay for information to and from the peripheral nervous system and higher processing centers of the brain.

Question 58

Summarize the role of the major structure of the limbic system in memory.

Answer 58

The hippocampus within the limbic system is involved in learning and memory. It communicates with the prefrontal area o the brain in these functions.

Question 59

Discuss why two forms of memory are needed by the body.

Answer 59

Short-term memory is useful in managing operations within the present by holding a thought in mind. Long-term memory involves semantic and episodic memory, as well as skill memory. It allows recall of the past and use of that information to shape future actions.

Question 60

Summarize the evidence from the mouse study that showed the role of glutamate in memory formation.

Answer 60

Mice that lack a glutamate receptor in their hippocampus were unable to learn to run mazes.

Question 61

Describe the specific functions of Broca’s and Wernicke’s areas.

Answer 61

Wernicke’s area is involved in the comprehension of speech. Broca’s area is involved in the actual motor function of speech.

Question 62

1. Which of the following neuron parts receive(s) signals from sensory receptors of other neurons?
   a) cell body
   b) axon
   c) dendrites
   d) both a and c

Answer 62

d) both a and c

Question 63

2. The neuroglia cells that form myelin sheaths in the CNS are called
   a) oligodendrocytes
   b) ganglionic cells
   c) Schwann cells
   d) astrocytes
   e) microglia

Answer 63

a) oligodendrocytes

Question 64

7. Which of the following cerebral areas is not correctly matched with its function?
   a) occipital lobe- vision
   b) parietal lobe- somatosensory area
   c) temporal lobe- primary motor area
   d) frontal lobe- Broca’s motor speech area

Answer 64

c) temporal lobe- primary motor area

Question 65

8. This part of the brain forms the link between the nervous system and the endocrine system
   a) corpus callosum
   b) amygdala
   c) reticular formation
   d) hypothalamus

Answer 65

d) hypothalamus

Question 66

9. The cerebellum
   a) coordinates skeletal muscle movements
   b) receives sensory input from the joints and muscles
   c) receives motor output from the cerebral cortex
   d) all of the above

Answer 66

d) all of the above

Question 67

10. The regulation of the information that is to be relayed to memory is the function of the
    a) reticular formation
    b) hippocampus
    c) hypothalamus
    d) cerebellum
    e) pons

Answer 67

b) hippocampus

Question 68

11. Memories are stored in the sensory association areas of the
    a) cerebral cortex
    b) spinal cord
    c) brain stem
    d) hypothalamus

Answer 68

a) cerebral cortex

Question 69

Describe how interoceptors are often involved in homeostasis.

Answer 69

Interoceptors are involved in regulating critical body functions like blood pressure, blood volume, and blood pH.

Question 70

List a specific example of each of the four types of sensory receptors.

Answer 70

Chemoreceptors-taste and smell
Photoreceptors- vision
Mechanoreceptors- hearing and balance
Thermoreceptors- heat and cold

Question 71

Explain why sensory adaptation is important to an organism.

Answer 71

Without sensory adaptation, we would constantly be stimulated by all sorts of inputs, which could overwhelm the brain’s ability to interpret.

Question 72

Define sensory receptor

Answer 72

Structure that receives either external or internal environmental stimuli and is a part of a sensory neuron or transmits signals to a sensory neuron.

Question 73

Define interoceptor

Answer 73

Sensory receptors of the peripheral nervous system that detect stimuli from inside the body.

Question 74

Define exteroceptor

Answer 74

Sensory receptors of the peripheral nervous system that detect stimuli from outside the body.

Question 75

Define chemoreceptor

Answer 75

Sensory receptor that is sensitive to chemical stimulation—for example, receptors for taste and smell.

Question 76

Define photoreceptor

Answer 76

Sensory receptor that responds to light stimuli.

Question 77

Define mechanoreceptor

Answer 77

Sensory receptor that responds to mechanical stimuli, such as pressure, sound waves, or gravity.

Question 78

Define thermoreceptor

Answer 78

Sensory receptor that detects heat.

Question 79

Define sensation

Answer 79

Processing of sensory stimuli that involves detection of nerve impulses by the cerebral cortex of the brain.

Question 80

Define perception

Answer 80

Processing of sensory stimuli that occurs when the brain interprets information being received from the sensory receptors.

Question 81

Define sensory transduction

Answer 81

Process by which a sensory receptor converts an input to a nerve impulse.

Question 82

Define integration

Answer 82

Summing up of excitatory and inhibitory signals by a neuron or by some part of the brain.

Question 83

Define sensory adaptation

Answer 83

Change in the sensitivity of a receptor that usually makes the receptor less sensitive to its stimulus.

Question 84

Explain the role, and specific location, of mechanoreceptors involved in maintain balance and equilibrium.

Answer 84

a) Rotational equilibrium. The ampullae of the semicircular canals contain hair cells with stereocilia embedded in a cupula. When the head rotates, the cupula is displaced, bending the stereocilia. This sends nerve impulses via the vestibular nerve to the brain.

b) Gravitational equilibrium. The utricle and the saccule contain hair cells with stereocilia embedded in an otolithic membrane. When the head bends, otoliths are displaced, causing the membrane to sag and the stereocilia to bend. The direction the stereocilia bend tells the brain in which direction the head moved.

Question 85

Classify each of the following as being associated with either the semicircular canals or the vestibule: ampulla, cupula, otoliths, saccule, and utricle.

Answer 85

The ampulla and cupula are associated with the semicircular canals; the otoliths, saccule, and utricle are associated with the vestibule.

Question 86

Explain how having two separate systems for equilibrium provided more complete information than one system could.

Answer 86

Having two systems for equilibrium allows the brain to receive information about rotational movement from the semicircular canals, and about the body’s position at rest from the vestibule. Although it might be possible to distinguish between these with just one system, it would not be as efficient or sensitive.

Question 87

Define rotational equilibrium

Answer 87

Maintenance of balance when the head and body are suddenly moved or rotated.

Question 88

Define gravitational equilibrium

Answer 88

Maintenance of balance when the head and body are motionless.

Question 89

Define utricle

Answer 89

Cavity in the vestibule of the vertebrate inner ear; contains sensory receptors for gravitational equilibrium.

Question 90

Define saccule

Answer 90

Saclike cavity in the vestibule of the vertebrate inner ear; contains sensory receptors for gravitational equilibrium.

Question 91

Define otolith

Answer 91

Calcium carbonate granule associated with sensory receptors for detecting movement of the head; in vertebrates, located in the utricle and saccule.

Question 92

Classify which specific types of somatic sensory receptors are interoceptors and which are exteroceptors.

Answer 92

Somatic sensory receptors that are interoceptors include proprioceptors (such as muscle spindles and Golgi tendon organs), and pain receptors in the skin and internal organs. Somatic sensory receptors that are exteroceptors include cutaneous receptors like Meissner corpuscles, Krause end bulbs, Merkel disks, Pacinian corpuscles, Ruffini endings, and free nerve endings sensitive to temperature.

Question 93

Classify the cutaneous receptors by their location (i.e., in the dermis or epidermis).

Answer 93

Free nerve endings- pain, heat, cold
Merkel disks- touch
Krause end bulbs- touch
Root hair plexus- touch
Meissner corpuscles- touch
Pacinian corpuscles- pressure
Riffini endings- pressure

Question 94

Predicts the likely outcome if an individual lacked muscle spindles; or pain receptors.

Answer 94

Someone who lacks muscle spindles would be susceptible to injuring their muscles and joints due to a lack of awareness of limb position and degree of muscle contraction. A person who lacked pain receptors would be without the benefit of the protective function of pain and would be very prone to injury.

Question 95

Define proprioceptors

Answer 95

Class of mechanoreceptor responsible for maintaining the body’s equilibrium and posture; involved in reflex actions.

Question 96

Define cutaneous receptors

Answer 96

Sensory receptor of the dermis that is activated by touch, pain, pressure, and temperature.

Question 97

Define pain receptors

Answer 97

Sensory receptors that are sensitive to chemicals released by damaged cells; also called nociceptors.

Question 98

Compare and contrast the functions of the chemoreceptors on the tongue and in the nasal cavity.

Answer 98

The tongue has taste cells and the nasal cavity has olfactory cells. Both are chemoreceptors to which molecules bind and nerve impulses are sent to the brain. The tongue has five types of taste cells distributed over the tongue, while there are about 1000 different types f olfactory cells in the olfactory epithelium.

Question 99

Predict some structural variations that could provide certain animals, such as dogs, with a sense of smell thousands o times more sensitive than that of humans.

Answer 99

Adaptations that allow some animals to have a more sensitive sense of smell would unclude having a greater number of olfactory receptors (and increased space in the nasal cavity for these receptors) and having more sensory nerve axons to receive signals from these receptors.

Question 100

Describe the anatomical connections that exist in the brain between smells and memories.

Answer 100

The olfactory bulbs in the brain have direct connections to centers for memory in the limbic system.

Question 101

Define taste buds.

Answer 101

Structure in the vertebrate mouth containing sensory receptors for taste; in humans, most taste buds are on the tongue.

Question 102

Define olfactory cells

Answer 102

Modified neuron that is a sensory receptor for the sense of smell.

Question 103

List all tissues that light passes through from when it enters the eye until it is converted into a nerve impulse.

Answer 103

Conjunctiva, cornea, aqueous humor in the anterior compartment, through the iris, lens, vitreous humor in the posterior compartment, retina including the ganglion cell layer, bipolar cell layer, and finally the rod cell and cone cell layer where light is converted to nerve impulses.

Question 104

Describe how the ciliary muscle controls the shape of the lens.

Answer 104

When the ciliary muscle is relaxed, the suspensory ligaments that attach to the lens are taut, which causes the lens to become flatter. When the ciliary muscle contracts, the suspensory ligaments are relaxed, allowing the lens to become more round.

Question 105

Explain how the number of rod or cone cells synapsing on a single ganglion cell allows cones to produce a clearer image.

Answer 105

As many as 150 rod cells, but perhaps only one cone cell, synapse(s) on an individual ganglion cell, so that more information can be sent to the brain for an individual cone cell versus a rod cell.

Question 106

Describe how the anatomy of the optic chiasma implies that the brain interprets visual information that has been “split” in half.

Answer 106

The optic chiasma is X-shaped, formed by the optic nerve fibers crossing over. The image sent to the brain is split because one side of the optic tract carries information about the opposite side of the visual field. The two sides of the visual field must communicate with each other in the brain for perception of the entire visual field.

Question 107

Define sclera

Answer 107

White, fibrous, outer layer of the eyeball.

Question 108

Define cornea

Answer 108

Transparent, anterior portion of the outer layer of the eyeball.

Question 109

Define conjunctiva

Answer 109

Delicate membrane that lines the eyelid, protecting the sclera.

Question 110

Define choroid

Answer 110

Vascular, pigmented middle layer of the eyeball.

Question 111

Define iris

Answer 111

Muscular ring that surrounds the pupil and regulates the passage of light through this opening.

Question 112

Define pupil

Answer 112

Opening in the center of the iris of the vertebrate eye.

Question 113

Define ciliary muscle

Answer 113

Within the ciliary body of the vertebrate eye, the ciliary muscle controls the shape of the lens.

Question 114

Define lens

Answer 114

Transparent “disk” structure found in the vertebrate eye behind the iris; brings objects into focus on the retina.

Question 115

Define retina

Answer 115

Innermost layer of the vertebrate eyeball, containing the photoreceptors—rod cells and cone cells.

Question 116

Define fovea centralis

Answer 116

Region of the retina consisting of densely packed cones; responsible for the greatest visual acuity.

Question 117

Define visual accommodation

Answer 117

Ability of the eye to focus at different distances by changing the curvature of the lens.

Question 118

Define rod cells

Answer 118

Photoreceptor in vertebrate eyes that responds to dim light.

Question 119

Define cone cells

Answer 119

Photoreceptor in vertebrate eyes that responds to bright light and makes color vision possible.

Question 120

Rhodopsin

Answer 120

Light-absorbing molecule in rod cells and cone cells that contains a pigment and the protein opsin.

Question 121

Define retinal

Answer 121

Light-absorbing molecule found in the photoreceptors of the eye; usually combined with opsin to form rhodopsin.

Question 122

Define color vision

Answer 122

Ability of the eye to detect specific wavelengths of light; involves specialized cone cells that detect blue, green, and red wavelengths.

Question 123

Define blind spot

Answer 123

Region of the retina, lacking rods or cones, where the optic nerve leaves the eye.

Question 124

Identify all structures of the ear that are involved with hearing and describe their functions.

Answer 124

Sound waves travel down the auditory canal to the tympanic membrane, and then to the bones of the middle ear, which are connected to the cochlea in the inner ear. It is in the cochlea that the sound waves are converted to neural impulses that are transmitted to the brain.

Question 125

Where are the mechanoreceptors in the inner ear that transduce sound waves into nerve impulses located?

Answer 125

The mechanoreceptors responsible for transducing sound waves into nerve impulses are located on hair cells on the basilar membrane of the spiral organ in the cochlea of the inner ear.

Question 126

Discuss how the distribution off stereocilia along the spiral organ allows the brain to perceive different pitches.

Answer 126

Sound waves transmitted via the oval window cause the basilar membrane to vibrate. Near the tip of the spiral organ, the basilar membrane vibrates more in response to higher pitched sound, and at the base it responds to lower pitches. Different sensory nerves supply each part of the basilar membrane, and take information to different part of the auditory cortex, where the pitch is interpreted.

Question 127

Explain how the brain distinguishes the volume of a sound.

Answer 127

Loud sounds cause the basilar membrane to vibrate more rapidly, which is interpreted by the brain as volume.

Question 128

Define hair cells

Answer 128

Cells located in the inner ear that function as mechanoreceptors for hearing.

Question 129

Define outer ear

Answer 129

Portion of the ear consisting of the pinna and the auditory canal.

Question 130

Define pinna

Answer 130

External flap of the ear; serves to collect and funnel sound toward the middle ear.

Question 131

Define auditory canal

Answer 131

Structure that funnels sounds from the outer ear to the middle ear.

Question 132

Define middle ear

Answer 132

Portion of the ear consisting of the tympanic membrane, the oval and round windows, and the ossicles, where sound is amplified.

Question 133

Define tympanic membrane

Answer 133

Membranous region that receives air vibrations in an auditory organ; in humans, the eardrum.

Question 134

Define oval window

Answer 134

Structure of the middle ear that conducts sound from the middle ear to the inner ear.

Question 135

Define round window

Answer 135

Structure of the middle ear that assists in the transmission of sound from the middle ear to the inner ear.

Question 136

Define ossicles

Answer 136

The small bones of the vertebrate middle ear—malleus, incus, and stapes.

Question 137

Define malleus

Answer 137

Bone found in the middle ear that assists in the transmission of sound to the inner ear; also called the hammer.

Question 138

Define incus

Answer 138

Bone found in the middle ear that assists in the transmission of sound to the inner ear; also called the anvil.

Question 139

Define stapes

Answer 139

Bone found in the middle ear that assists in the transmission of sound to the inner ear; also called the stirrup.

Question 140

Define auditory tube

Answer 140

Also called the eustachian tube; connects the middle ear to the nasopharynx for the equalization of pressure.

Question 141

Define inner ear

Answer 141

Portion of the ear consisting of a vestibule, semicircular canals, and the cochlea where equilibrium is maintained and sound is transmitted.

Question 142

Define semicircular canal

Answer 142

One of three half-circle-shaped canals of the vertebrate inner ear; contains sensory receptors for rotational equilibrium.

Question 143

Define vestibule

Answer 143

Space or cavity at the entrance to a canal, such as the cavity that lies between the semicircular canals and the cochlea.

Question 144

Define cochlea

Answer 144

Spiral-shaped structure of the vertebrate inner ear containing the sensory receptors for hearing.

Question 145

Define organ of Corti

Answer 145

Structure in the vertebrate inner ear that contains auditory receptors (also called spiral organ).

Question 146

These receptors detect stimuli within the body.
a) interoceptors
b) exteroceptors
c) homeoreceptors
d) reflec receptors

Answer 146

a) interoceptors

Question 147

A receptor that detects changes in pH, or specific molecules in the environment, would be classifies as a
a) mechanoreceptor
b) photoreceptor
c) chemoreceptor
d) thermoreceptor
e) none of the above

Answer 147

c) chemoreceptor

Question 148

Where does the process of sensation occur in the body?
a) at the sensory receptor
b) in the spinal cord
c) within the synapses between neurons of the PNS
d) in the cerebral cortex
e) all of the above

Answer 148

d) in the cerebral cortex

Question 149

Which type of receptor detect the chemicals released by damaged tissues?
a) nociceptors
b) proprioceptors
c) Meissner corpuscles
d) Ruffini endings
e) None of the above

Answer 149

a) nociceptors

Question 150

Which of the following types of receptors assists in the maintenance of muscle tone?
a) nociceptors
b) proprioceptors
c) Pacinian corpuscles
d) Krause end bulbs
e) all of the above

Answer 150

b) proprioceptors

Question 151

The sense of taste and smell rely primarily on what types of receptors?
a) mechanoreceptors
b) nociceptors
c) protoreceptors
d) proprioceptors
e) chemoreceptors

Answer 151

e) chemoreceptors

Question 152

7. Olfactory bulbs are located
   a) on the tongue
   b) in the nasal cavity
   c) in the brain stem
   d) in the aorta
   e) none of the above

Answer 152

b) in the nasal cavity

Question 153

9. Which structure of the eye is incorrectly matched with its function
   a) lens-focusing
   b) cones-color vision
   c) iris-regulation of amount of light
   d) choroid- location of cones
   e) sclera- protection

Answer 153

d) choroid- location of cones

Question 154

10. Adjustment of the lens to focus on objects close to the viewer is called
    a) convergence
    b) focusing
    c) visual accommodation
    d) constriction

Answer 154

c) visual accommodation

Question 155

12. Which of the following is (are) not involved in the sense of hearing
    a) auditory canal
    b) tympanic membrane
    c) ossicles
    d) semicircular canals
    e) cochlea

Answer 155

d) semicircular canals

Question 156

Which of these correctly describes the location of the spiral organ?
a) between the tympanic membrane and the oval window in the inner ear
b) in the utricle and saccule within the vestibule
c) between the tectorial membrane and the basilar membrane in the cochlear canal
d) between the nasal cavities and the throat
e) between the outer and inner ear within the semicircular canals

Answer 156

c) between the tectorial membrane and the basilar membrane in the cochlear canal

Question 157

Which of the following structures would allow you to know that you were upside down, even if you were in total darkness?
a) utricle and saccule
b) cochlea
c) semicircular canals
d) tectorial membrane

Answer 157

a) utricle and saccule

Question 158

Rotational equilibrium is established by which of the following?
a) the semicircular canals
b) the utricle and saccule
c) the cochlea
d) the auditory canal
e) none of the above

Answer 158

a) the semicircular canals

Question 159

Some sensory receptors, such as those for taste, smell, and pressure, readily undergo the process of sensory adaptation, or decreased response to stimulus. In contrast, receptors for pain are less prone too adaptation. Why does this make good biological sense? What do you think happens to children who are born without the ability to feel pain normally?

Answer 159

Without sensory adaptation to constant everyday stimuli, we would constantly be bombarded with and distracted by a huge amount of sensory data ( about touch, temperature, pressure, etc.). In contrast, there are large risks forgo not responding to pain, as shown by the damage that occurs to people who lack pain perception.

Question 160

Trace the path of a photon of light through all the layers of the retina discussed in this chapter. Then, trace the nerve impulse from a photoreceptor located on the right side of the left eyeball through the visual cortex.

Answer 160

Once it reaches the retina, light must pass through layers of axons, ganglion cells, and bipolar cells before it reaches the rod or cone cells. From the right side of the left eyeball, nerve impulses travel via the optic nerve through the optic chiasma, then through the right optic tract, until they synapse with neurons in the thalamus. Axons from thalamic neurons transmit this information to the visual area of the occipital cortex.

Question 161

The density of taste buds on the tongue can vary. Some obese individuals have a lower density of taste buds than usual. Assume that taste perception is related to taste bud density. If so, what hypothesis would you test to see if there is a relationship between taste bud density and obesity.

Answer 161

The null hypothesis would be that there is no association with taste bud density and obesity. The prediction based on this hypothesis is that obese people will have the same density as normal weight people.

Question 162

List 6 major human endocrine organs

Answer 162

Hypothalamus, pituitary gland, thyroid gland, adrenal glands, thymus, and pancreas.

Question 163

Explain what it means to say that secretion o a hormone is regulated by negative feedback.

Answer 163

When an endocrine gland is controlled by negative feedback, it is sensitive to the condition it is regulating or the blood level of the hormone it is producing.

Question 164

Explain why second messengers are needed for peptide hormones.

Answer 164

Peptide hormones bind to receptors in the plasma membrane and do not enter the cell. A second messenger inside the cell is needed to initiate an enzyme cascade.

Question 165

Provide a specific example that suggests human behavior may be influenced by pheromones.

Answer 165

It has been found that women prefer axillary odors from men with different MHC than themselves.

Question 166

Define endocrine system

Answer 166

Organ system involved in the coordination of body activities; uses hormones as chemical signals secreted into the bloodstream.

Question 167

Define hormones

Answer 167

Chemical messenger, produced in one part of the organism, that controls the activity of other tissues or organs in that organism.

Question 168

Define growth factors

Answer 168

A hormone or chemical, secreted by one cell, that may stimulate or inhibit growth of another cell or cells.

Question 169

Define endocrine glands

Answer 169

Ductless organ that secretes hormone(s) into the bloodstream.

Question 170

Define negative feedback

Answer 170

Mechanism of homeostatic response by which the output of a system suppresses or inhibits activity of the system.

Question 171

Peptide hormone

Answer 171

Type of hormone that is a protein, a peptide, a glycoprotein, or is derived from an amino acid.

Question 172

Define steroid hormone

Answer 172

Type of hormone that has a complex of 4-carbon rings, but each one has different side chains.

Question 173

Define first messenger

Answer 173

Chemical signal, such as a peptide hormone, that binds to a plasma membrane receptor protein and alters the metabolism of a cell because a second messenger is activated.

Question 174

Define second messenger

Answer 174

Chemical signal, such as cyclic AMP, that causes the cell to respond to the first messenger—a hormone bound to a plasma membrane receptor protein.

Question 175

Define pheromones

Answer 175

Chemical messenger that works at a distance and alters the behavior of another member of the same species.

Question 176

Explain how the posterior and anterior pituitary glands differ in the way they are controlled by the hypothalamus.

Answer 176

Neurons in the hypothalamus produce hormones that pass through axons into the posterior pituitary where they are stored. The hypothalamus controls the anterior pituitary by producing hormones that travel to the anterior pituitary through a portal system.

Question 177

List the hormones produced or released by the pituitary gland, and provide a function for each.

Answer 177

Antidiuretic (ADH)- Stimulates water reabsorption by kidneys

Oxytocin- Stimulates uterine muscle contraction, release of milk by mammary glands

Thyroid-Stimulating (TSH)- Stimulates thyroid

Adrenocorticotropic (ACTH)- Stimulates adrenal cortex

Gonadotropic (FSH,LH)- Egg and sperm production; sex hormone production

Prolactin (PRL)- Milk production

Growth (GH)- Cell division, protein synthesis, and bone growth

Melanocyte-stimulating (MSH)- Unknown function in humans; regulates skin color in lower vertebrates

Question 178

Describe how hormone secretion can be regulated by positive feedback, and provide an example.

Answer 178

The release of oxytocin from the posterior pituitary is controlled by positive feedback in which the amount of oxytocin released increases as the stimulus continues.

Question 179

Explain why cancer of the pituitary gland, which may affect any of its normal functions, might be difficult to diagnose.

Answer 179

Diagnosis is difficult because of the many hormones controlled by the pituitary and the many organs and tissues affected.

Question 180

Define hypothalamus

Answer 180

In vertebrates, part of the brain that helps regulate the internal environment of the body—for example, heart rate, body temperature, and water balance.

Question 181

Define pituitary gland

Answer 181

Small gland that lies just inferior to the hypothalamus; consists of the anterior and posterior pituitary, both of which produce hormones.

Question 182

Define antidiuretic hormone (ADH)

Answer 182

Hormone, secreted by the posterior pituitary, that increases the permeability of the collecting ducts in a kidney.

Question 183

Define posterior pituitary

Answer 183

Portion of the pituitary gland that stores and secretes oxytocin and antidiuretic hormone produced by the hypothalamus.

Question 184

Define oxytocin

Answer 184

Hormone, released by the posterior pituitary, that causes contraction of the uterus and milk letdown.

Question 185

Define positive feedback

Answer 185

Mechanism of homeostatic response in which the output of the system intensifies and increases the activity of the system.

Question 186

Define hypothalamic-releasing hormone

Answer 186

One of many hormones, produced by the hypothalamus, that stimulates the secretion of an anterior pituitary hormone.

Question 187

Define hypothalamic-inhibiting hormone

Answer 187

One of many hormones, produced by the hypothalamus, that inhibits the secretion of an anterior pituitary hormone.

Question 188

Define anterior pituitary

Answer 188

Portion of the pituitary gland that is controlled by the hypothalamus and produces six types of hormones, some of which control other endocrine glands.

Question 189

Define thyroid-stimulating hormone (TSH)

Answer 189

Substance produced by the anterior pituitary that causes the thyroid to secrete thyroxine and triiodothyronine.

Question 190

Define adrenocorticotropic hormone (ACTH)

Answer 190

Hormone secreted by the anterior lobe of the pituitary gland that stimulates activity in the adrenal cortex.

Question 191

Define follicle-stimulating hormone (FSH)

Answer 191

Hormone released by the anterior pituitary; in males, it promotes the production of sperm; in females, it promotes the development of the follicle in the ovary.

Question 192

Define luteinizing hormone (LH)

Answer 192

Hormone released by the anterior pituitary; in males, it regulates the production of testosterone by the interstitial cells; in females, it promotes the development of the corpus luteum in the ovary; also called interstitial cell-stimulating hormone (ICSH) in males.

Question 193

Define gonadotropic hormone

Answer 193

Substance, secreted by the anterior pituitary, that regulates the activity of the ovaries and testes; principally, follicle-stimulating hormone (FSH) and luteinizing hormone (LH).

Question 194

Define prolactin

Answer 194

Hormone secreted by the anterior pituitary that stimulates the production of milk from the mammary glands.

Question 195

Define melanocyte-stimulating hormone (MSH)

Answer 195

Substance that causes melanocytes to secrete melanin in most vertebrates.

Question 196

Define growth hormone (GH)

Answer 196

Substance secreted by the anterior pituitary; controls size of an individual by promoting cell division, protein synthesis, and bone growth.

Question 197

Explain how the amount of T3 and T4 secreted by the thyroid gland is controlled.

Answer 197

Levels of T3 and T4 are controlled by negative feedback. When levels of T3 and T4 rise, the anterior pituitary stops producing thyroid-stimulating hormone.

Question 198

Describe the symptoms that might be expected in a person with a thyroid tumor that was producing excess calcitonin.

Answer 198

Calcitonin decreases blood calcium by increasing calcium deposition in bones. A person with a calcitonin-producing thyroid tumor would be expected to have low calcium levels, leading to disrupted nerve conduction, muscle contraction, and blood clotting, as well as increased bone density.

Question 199

Predict the expected effect(s) of removal of the parathyroid glands.

Answer 199

Parathyroid hormone increases the activity of osteoclasts, promotes reabsorption of calcium by the kidneys, causes blood phosphate to decrease, and activates vitamin D, so removal of the parathyroid glands would tend to cause decreased blood calcium and increased blood phosphate.

Question 200

Define thyroid gland

Answer 200

Large gland in the neck that produces several important hormones, including thyroxine, triiodothyronine, and calcitonin.

Question 201

Define parathyroid gland

Answer 201

Gland embedded in the posterior surface of the thyroid gland; it produces parathyroid hormone.

Question 202

Define thyroxine (T4)

Answer 202

Hormone secreted from the thyroid gland that promotes growth and development; in general, it increases the metabolic rate in cells.

Question 203

Define calcitonin

Answer 203

Hormone secreted by the thyroid gland that increases the blood calcium level.

Question 204

Define parathyroid hormone (PTH)

Answer 204

Hormone secreted by the four parathyroid glands that increases the blood calcium level and decreases the phosphate level.

Question 205

Explain how the secretion of hormones by the adrenal medulla and cortex is controlled.

Answer 205

Secretion of hormones by the adrenal medulla is under direct nervous control. Secretions of the adrenal cortex are controlled either by the release of ACTH from the anterior pituitary (for glucocorticoids) or by the renin-angiotensin system (for mineralcorticoids).

Question 206

Summarize how the hormones produced by the adrenal glands help the body respond to stress.

Answer 206

Epinephrine from the adrenal medulla helps the body deal with stress by activating the fight-or-flight response (increased heart rate, blood pressure, and energy level). Glucocorticoids from the adrenal cortex raise blood glucose levels and inhibit the body’s inflammatory response.

Question 207

Describe the specific effect of aldosterone on the kidney.

Answer 207

Aldosterone causes the kidneys to absorb sodium and excrete potassium, which generally raises blood pressure.

Question 208

Define adrenal gland

Answer 208

Gland that lies atop a kidney; the adrenal medulla produces the hormones epinephrine and norepinephrine, and the adrenal cortex produces the glucocorticoid and mineralocorticoid hormones.

Question 209

Define adrenal medulla

Answer 209

Inner portion of the adrenal gland; secretes the hormones epinephrine and norepinephrine.

Question 210

Define adrenal cortex

Answer 210

Outer portion of the adrenal gland; secretes mineralocorticoids, such as aldosterone, and glucocorticoids, such as cortisol.

Question 211

Define epinephrine

Answer 211

Hormone secreted by the adrenal medulla in times of stress; also referred to as adrenaline.

Question 212

Define norepinephrine

Answer 212

Neurotransmitter of the postganglionic fibers in the sympathetic division of the autonomic system; also, a hormone produced by the adrenal medulla. Sometimes referred to as noradrenaline.

Question 213

Define mineralocorticoid

Answer 213

Hormone secreted by the adrenal cortex that regulates salt and water balance, leading to increases in blood volume and blood pressure.

Question 214

Define gluccorticoid

Answer 214

Type of hormone secreted by the adrenal cortex that influences carbohydrate, fat, and protein metabolism; see also cortisol.

Question 215

Define cortisol

Answer 215

Glucocorticoid secreted by the adrenal cortex that responds to stress on a long-term basis; reduces inflammation and promotes protein and fat metabolism.

Question 216

Define aldosterone

Answer 216

Hormone secreted by the adrenal cortex that regulates the sodium and potassium ion balance of the blood.

Question 217

Define renin

Answer 217

Enzyme released by the kidneys that leads to the secretion of aldosterone and a rise in blood pressure.

Question 218

Define atrial natriuretic hormone (ANH)

Answer 218

Hormone secreted by the heart that increases sodium excretion by inhibiting the secretion of aldosterone.

Question 219

Distinguish between the endocrine and exocrine functions of the pancreas.

Answer 219

The exocrine tissue of the pancreas produces and secretes juices that help in digestion in the small intestine. The endocrine cells of the pancreas produce the hormones glucagon, insulin, and somatostatin.

Question 220

Describe how pancreatic hormones interact to regulate blood glucose levels.

Answer 220

When the blood glucose level is high, the pancreas secretes insulin. Insulin promotes the storage of glucose as glycogen and the synthesis of proteins and fats (as opposed to their use as energy sources). Therefore, insulin lower the blood glucose level to normal.
When the blood glucose level is low, the pancreas secretes glucagon. Glucagon acts opposite to insulin. Therefore, glucagon raises the blood glucose level to normal.

Question 221

Review the effect of somatostatin on other hormones, such as insulin and glucagon.

Answer 221

Somatostatin inhibits the release of growth hormone and suppresses glucagon and insulin secretion by negative feedback mechanism.

Question 222

Define pancreas

Answer 222

Internal organ that produces digestive enzymes and the hormones insulin and glucagon.

Question 223

Define pancreatic islet

Answer 223

Masses of cells that constitute the endocrine portion of the pancreas.

Question 224

Define insulin

Answer 224

Hormone, released by the pancreas, that serves to lower blood glucose levels by stimulating the uptake of glucose by cells, especially muscle and liver cells.

Question 225

Define glucagon

Answer 225

Hormone, produced by the pancreas, that stimulates the liver to break down glycogen, thus raising blood glucose levels.

Question 226

Define somatostatin

Answer 226

Hormone, produced by the pancreas, stomach, and small intestine, that inhibits the effects of growth hormones; also suppresses activity of hormones such as insulin and glucagon.

Question 227

Summarize the role of testosterone and estrogen in the body.

Answer 227

Testosterone and estrogen stimulate the development of male and female sex characteristics and the production of gametes.

Question 228

List some of the undesirable side effects of anabolic steroid use.

Answer 228

Some of the worst side effects from taking anabolic steroids are liver disfunction and cancer, kidney disease, heart damage, stunted growth, infertility, and impotency.

Question 229

Describe the normal function of leptin.

Answer 229

Leptin signals satiety, a sense of not being hungry.

Question 230

Explain why prostaglandins are considered to be local hormones.

Answer 230

Prostaglandins are not distributed in the blood, but instead act close to where they are produced within cells.

Question 231

Define gonads

Answer 231

Organ that produces gametes; the ovary produces eggs, and the testis produces sperm.

Question 232

Define testes

Answer 232

Male gonads that produce sperm and the male sex hormones.

Question 233

Define androgens

Answer 233

Male sex hormone (e.g., testosterone).

Question 234

Define ovaries

Answer 234

In flowering plants, the enlarged, ovule-bearing portion of the carpel that develops into a fruit; female gonad in animals that produces an egg and female sex hormones.

Question 235

Define anabolic steroid

Answer 235

Synthetic steroid that mimics the effect of testosterone.

Question 236

Define estrogen

Answer 236

Female sex hormone that helps maintain sexual organs and secondary sex characteristics.

Question 237

Define progesterone

Answer 237

Female sex hormone that helps maintain sexual organs and secondary sex characteristics.

Question 238

Define thymus

Answer 238

Lymphoid organ involved in the development and functioning of the immune system; T lymphocytes mature in the thymus.

Question 239

Define pineal gland

Answer 239

Gland—either at the skin surface (fish, amphibians) or in the third ventricle of the brain (mammals)—that produces melatonin.

Question 240

Define melatonin

Answer 240

Hormone, secreted by the pineal gland, that is involved in biorhythms.

Question 241

Define circadian rhythm

Answer 241

Biological rhythm with a 24-hour cycle.

Question 242

Define leptin

Answer 242

Hormone produced by adipose tissue that acts on the hypothalamus to signal satiety (fullness).

Question 243

Define growth factor

Answer 243

A hormone or chemical, secreted by one cell, that may stimulate or inhibit growth of another cell or cells.

Question 244

Define prostaglandin

Answer 244

Hormone that has various and powerful local effects.

Question 245

Explain how ADH is related to an increased urge to urinate when one drinks alcohol.

Answer 245

ADH causes more water to be reabsorbed in the kidneys, decreasing urine volume. Inhibition of ADH secretion by alcohol results in increased amounts of urine and frequency of urination.

Question 246

Describe why a goiter forms in iodine deficiency.

Answer 246

In iodine deficiency, the thyroid gland cannot synthesize enough T3 and T4. The anterior pituitary responds by releasing large amounts of TSH, which stimulates the thyroid gland to enlarge.

Question 247

Differentiate the role of antibodies in causing Graves disease versus Addison disease.

Answer 247

In Addison disease, antibodies play a role in destruction of the adrenal cortex by the immune system. In Graves disease, antibodies bind to the TSH receptor, stimulating production of T3 and T4 rather than destroying the gland.

Question 248

Describe the causes and treatment of type 1 and type 2 diabetes.

Answer 248

Type 1 diabetes is due to an insulin shortage and is treated by the administration of insulin. Type 2 results from an insensitivity to insulin, often specifically due to insufficient numbers of insulin receptors on cells. It is treated with medications, weight loss, and increased exercise.

Question 249

Define diabetes insipidus

Answer 249

Condition caused by a lack of antidiuretic hormone (ADH); characterized by excessive thirst and overproduction of urine.

Question 250

Define pituitary dwarfism

Answer 250

Condition caused when too little growth hormone is produced during childhood. Individuals with this condition have a small stature, but have body parts in normal proportions.

Question 251

Define gigantism

Answer 251

Condition caused by the overproduction of growth hormone during childhood; individuals often also have diabetes mellitus and other health problems.

Question 252

Define acromegaly

Answer 252

Condition caused by an overproduction of growth hormones as an adult.

Question 253

Define Cushing syndrome

Answer 253

Condition caused by the overproduction of ACTH, resulting in too much cortisol in the body.

Question 254

Define hypothyroidism

Answer 254

Caused by the under-secretion of hormones from the thyroid gland; symptoms include weight gain, lethargic behavior, and depression.

Question 255

Define hypothyroidism

Answer 255

Caused by the oversecretion of hormones from the thyroid gland; symptoms include hyperactivity, nervousness, and insomnia.

Question 256

Define Graves disease

Answer 256

Disease associated with the overproduction of T3 and T4 by the thyroid; caused by antibodies that interact with TSH receptors in the thyroid.

Question 257

Define Addison disease

Answer 257

Condition caused by an insufficient production of cortisol by the adrenal glands.

Question 258

Define diabetes mellitus

Answer 258

Condition caused by an insulin imbalance in the body; type 1 diabetes results from not enough insulin being produced; type 2 diabetes is caused by the body (specifically adipose tissue) not responding to insulin in the blood.

Question 259

2. Peptide hormones interact with which structures on the surface of a cell?
   a) receptor proteins
   b) second messenger systems
   c) pheromones
   d) neurotransmitters
   e) digestive enzymes

Answer 259

a) receptor proteins

Question 260

3. A _________ requires the use of a second messenger system to enter a cell.
   a) steroid hormone
   b) peptide hormone
   c) pheromone
   d) all of the above

Answer 260

b) peptide hormone

Question 261

4. Which of the following acts as the link between the nervous system and the endocrine system?
   a) posterior pituitary gland
   b) hypothalamus
   c) anterior pituitary gland
   d) parathyroid

Answer 261

b) hypothalamus

Question 262

5. Growth hormone (GH) is released by which endocrine gland?
   a) posterior pituitary gland
   b) hypothalamus
   c) anterior pituitary gland
   d) adrenal gland

Answer 262

c) anterior pituitary gland

Question 263

Which of the following hormones is regulated by positive feedback mechanisms?
a) thyroid-stimulating hormone (TSH)
b) gonadotropic hormone
c) oxytocin
d) growth hormone
e) none of the above

Answer 263

c) oxytocin

Question 264

7. Thyroid hormones directly regulate which aspect of human physiology?
   a) circadian rhythm
   b) stress response
   c) sex hormone production
   d) metabolic rate
   e) none of the above

Answer 264

d) metabolic rate

Question 265

8. Which of the following hormones increases blood calcium levels?
   a) calcitonin
   b) thyroxine (T4)
   c) parathyroid hormone
   d) mineralocorticoid

Answer 265

c) parathyroid hormone

Question 266

9. Which of the following hormones is (are) not produced by the adrenal cortex?
   a) glucocorticoids
   b) mineralocorticoids
   c) gonadocorticoids
   d) norepinephrine

Answer 266

d) norepinephrine

Question 267

10. Which of the following is not correct regarding aldosterone?
    a) It is produced by the adrenal cortex
    b) It is inhibited by the action of epinephrine
    c) Its release is regulated by renin from the kidneys
    d) It causes the kidneys to reabsorb sodium (Na+) ions.
    e) all of the above

Answer 267

b) It is inhibited by the action of epinephrine

Question 268

11. Which of the following correctly describes the hormone insulin?
    a) It is produced by B cells in the pancreas
    b) It increases glucose uptake by liver and muscle cells
    c) It is a peptide hormone
    d) It lowers blood glucose levels
    e) all of the above

Answer 268

e) all of the above

Question 269

12. The hormone antagonistic to insulin is
    a) epinephrine
    b) parathyroid hormone
    c) glucagon
    d) cortisol
    e) progesterone

Answer 269

c) glucagon

Question 270

13. The hormone produced by the pineal gland to regulate the circadian rhythm is called
    a) estradiol
    b) melatonin
    c) renin
    d) aldosterone
    e) none of the above

Answer 270

b) melatonin

Question 271

14. The disease that is believed to be caused by an autoimmune response that destroys the pancreatic islets is called
    a) Addison disease
    b) diabetes insipidus
    c) type 1 diabetes mellitus
    d) types 2 diabetes mellitus
    e) gestational diabetes

Answer 271

c) type 1 diabetes mellitus

Question 272

15. Which hormone and condition are mismatched?
    a) growth hormone-acromegaly
    b) thyroxine- goiter
    c) parathyroid hormone-tetany
    d) cortisol- myxedema
    e) insulin-diabetes

Answer 272

d) cortisol- myxedema

Question 273

Because some of their functions overlap, why is it necessary to have both a nervous system and an endocrine system?

Answer 273

The nervous system allows for quick, almost immediate responses to stress or danger, and fine-tuning of all other bodily function (plus all the other benefits of higher bran functions), while the endocrine system provides longer-lasting responses.

Question 274

Certain endocrine disorders, such as Cushing syndrome, can be caused by excessive secretion of a hormone ( in this case, ACTH) by the pituitary gland, or by a problem with the adrenal gland itself. I you were able to measure the ACTH levels of a Cushing patient, how could you tell the difference between a pituitary problem and a primary adrenal gland problem?

Answer 274

If Cushing syndrome is caused by a problem (such as cancer) of the adrenal gland itself, ACTH levels would be very low, because of negative feedback action of cortisol on the hypothalamus/pituitary.