Princeton Review Ch 8 - Nervous and Endocrine System

Question 1

Cranial versus spinal nerves.

Answer 1

Cranial nerves convey sensory and motor information to and from the brainstem. 12 pairs.

Spanish nerves convey sensory and motor information to and from the spinal cord. 31 pairs.

Question 2

Vagus nerve function.

Answer 2

A cranial nerve that affects the heart and GI tract. Functions to decrease HR and increase GI activity, as such it is part of the parasympathetic division of the ANS.

Question 3

What do all somatic motor neurons of the PNS have in common?

Answer 3

All somatic motor neurons innervate skeletal muscles, use Ach as their NT, and have their cell bodies in the brain stem or ventral portion of the SC.

Question 4

What do all somatic sensory neurons of the PNS have in common.

Answer 4

All somatic sensory neurons have a long dendrite extending from a sensory receptor toward the soma, which is located just outside the CNS in a dorsal root ganglion. The DRG is a bunch of somatic and autonomic sensory neuron cell bodies located just dorsal to the spinal cord. The first synapse occurs in the CNS, either in the cord or all the way up to the brain stem.

Question 5

DRG.

Answer 5

The DRG is a bunch of somatic and autonomic sensory neuron cell bodies located just dorsal to the spinal cord. The DRG are protected within the vertebral column but are outside of the meninges (protective sheath of the brain and cord).

Question 6

Autonomic PNS organization.

Answer 6

The preganglionic neuron has its cell body in the brainstem or SC. It sends an axon to an autonotmic ganglion, located OUTSIDE of the SC. In the ganglion, the axon synapses with a post-ganglionic neuron. The postganglionic neuron sends an axon to an effector (smooth muscle or gland).

Question 7

All parasympathetic postganglionic neurons release?

Answer 7

Acetylcholine (ACh) as their NT

Question 8

Nearly all sympathetic postganglionic neurons release…

Answer 8

Norepinephrine as their NT

Question 9

Sympathetic NS versus Parasympathetic NS in terms of preganglionic axon, postganglionic axon, and ganglia.

Answer 9

Sym: Pre - short (ACh NT); ganglia is close to cord, far from target; Post - long (NE is NT)
Para: Pre - long (ACh NT); ganglia is far from cord; Post - short and close to target (ACh is NT)

Question 10

Describe the anatomy of the Adrenal Gland and which parts secrete what.

Answer 10

1) Medulla: inner portion; part of the sympathetic NS; upon activation of the SNS, the adrenal gland is stimulated to release epinephrine hormone; effects are rapid but short-lived
2) Cortex is an important endocrine gland that releases glucocorticoids (main one is cortisol) and mineralocorticoids (main is is aldosterone), and some sex hormones.

Question 11

Exteroreceptors versus interoreceptors.

Answer 11

Sensory exteroreceptors detect stimuli from the outside world. Interorecpetors respond to internal stimuli.

Question 12

Mechanoreceptors.

Answer 12

Respond to mechanical disturbances.

Question 13

Mechanoreceptors: Pacinian corpuscles, auditory hair cells, and vestibular hair cells.

Answer 13

1) Pressure sensors located deep within the skin. When the corpuscular MB is distorted by the pressure of the skin, the nerve ending becomes depolarized.
2) Hair cells are found in the cochlea of the inner ear and detects vibrations from sound waves
3) Vestibular hair cells are located in semicircular canals of the inner ear and detect acceleration and position relative to gravity.

Question 14

Chemoreceptors. Give two common examples.

Answer 14

Respond to chemical changes.

1) olfactory: detect airborne chemicals and allows us to smell things.
2) gustatory receptors are taste buds.
3) also chemoreceptors in the walls of the carotid and aortic arteries that respond to changes in arterial pH, PCO2, and PO2 levels.

Question 15

Nociceptors.

Answer 15

Pain receptors, which are simulated by tissue injury. These can be somatic or autonomic. Autonomic is not always detected but they give the sensating of aching pain.

Question 16

Thermoreceptors.

Answer 16

Stimulated by changes in temperature. Falls into three categories: cold sensitive, warm sensitive, and thermal nociceptors, which detect painful hot stimuli.

Question 17

Electromagnetic receptors

Answer 17

Stimulated by EM waves. Humans only have rods and cones. But in some animals, electroreceptors and magnetoreceptors are separate. Some fish can detect e fields. Some birds use magnetoreceptors to sense the Earth’s B-field, which helps them during migration.

Question 18

All sensory receptors need to encode relevant information regarding the nature of the stimulus being detected. Give 4 properties that need to be communicated to the CNS.

Answer 18

1) Stimulus modality: type of stimulus - the CNS determines this based on which type of receptor is firing
2) Location: communicated by the receptive field of the sensory receptor
3) Intensity: Coded by the frequency of action potentials. The range of intensities that can be detected by sensory receptors can be expanded by including multiple groups of receptors with limited ranges to detect a wider range over alll; ex. cones and vision
4) Duration: may or may not be coded explicitly. Tonic receptors fires AP as long as the stimulus is present. Phasic receptors fires AP only when the stimulus beings.

Question 19

Adaptation.

Answer 19

The decrease in firing frequency of action potentials when the intensity of the stimulus remains constant. Nociceptors are the only ones that don’t adapt because pain is the body telling us to do something about it.

Question 20

Proprioception.

Answer 20

Awareness of self (body part position)

Question 21

Muscle spindle, Golgi tendon organs, and joint capsule receptors.

Answer 21

1) A mechanoreceptors specialized to detect muscle stretch. 2) GTO - monitors tension in the tendons
3) Detect pressure, tension, and movement in the joints.

By monitoring all of this activity, we can coordination motion. The cerebellum is primarily responsible for this.

Question 22

How is gustation accomplished?

Answer 22

Taste receptors or taste buds can detect 5 flavors. Each one responds most strongly to ONE of these 5 stimuli. The bud is contains a taste pore with taste hairs that detect food chemicals. Info is transmitted via a cranial nerve to an area of the brain’s temporal lobe.

Question 23

How is olfaction (smelling) accomplished?

Answer 23

There are olfactory receptors in the roof of the nasopharynx (nasal cavity). The receptors detect airborne chemicals that dissolve in the mucous membranes of the nose. Olfactor nerves project directly to the olfactory bulb of the brain, located in the temporal lobe.

Question 24

Outer ear components.

Answer 24

Auricle, pinna and external auditory canal.

Question 25

Middle ear components.

Answer 25

The middle ear is divided from the outer ear by the tympanic membrane or eardrum. The middle ear consists of 3 small bones called the malleus (hammer), incus (anvil), and the stapes (stirrup). The stapes is attached to the oval window, the MB that divides the middle and inner ear.

Question 26

Inner ear components.

Answer 26

Structures of the inner ear include the cochlea, the semicircular canals, and the utricle and saccule. The semicircular canals are important for a sense of balance. The round window is a membrane-covered hole in the cochlea that relieves pressure. The Eustachian tube is the passageway from the back of the throat to the middle ear; equalizes pressure on both sides.

Question 27

Function of the round window.

Answer 27

The round window is a membrane-covered hole in the cochlea that relieves pressure.

Question 28

The function of the Eustachian tube (auditory tube)

Answer 28

The Eustachian tube is the passageway from the back of the throat to the middle ear. It functions to equalize pressure on both sides of the eardrum and is the cause of the ear popping one experiences at high altitudes or underwater.

Question 29

Mechanism of hearing, from outer to middle ear.

Answer 29

Sound waves enter the external ear into the auditory canal, causing the eardrum to vibrate. The malleus attached to the eardrum receives the vibrations, which are passed on to the incus and then to the stapes, which contacts the oval window and.

Question 30

Mechanism of hearing from middle ear to inner ear.

Answer 30

The vibration of the oval window creates pressure waves in the perilymph and endolymph, the fluids in the cochlea. The pressure waves in the endolymph cause vibration of the basilar membrane, a thin MB extending throughout the coiled length of the cochlea. The basilar MB is covered with hair cells, which are auditory receptors with cilia on the top. The hairs contact the techtorial MB, and when the basilar MB moves, the hairs are dragged across the tectorial MB and they bend. The displacement opens ion channels in the hair cells, which results in NT release. Dendrite from bipolar auditory afferent neurons are stimulated by this NT, and thus sound vibrations are convereted to nerve impulses.

Question 31

Organ or Corti.

Answer 31

The basilar membrane, hair cells, and tectorial membrane together are known as the Organ of Corti. The outer and middle ear convey sound waves t the cochlea, and the Organ of Corti is the primary site at which auditory stimuli are detected.

Question 32

Summary: from sound to hearing.

Answer 32

sound waves-> auricle->external auditory canal-> tympanic MB -> malleus -> incus -> stapes -> oval window->perilymph->endolymph->basilar MB -> auditory hair cell->tectorial MB -> NT stimulates bipolar auditory neurons -> brain -> perception.

Question 33

PItch and how it's distinguished.

Answer 33

The frequency of sound is distinguished by which regions of the basilar MB vibrate, stimulating different auditory neurons.

Question 34

Loudness and how it's distinguished.

Answer 34

The loudness of the sound is distinguished by the amplitude of vibration. Larger vibrations cause more frequent APs in the auditory neurons.

Question 35

Where in the brain is sound stimuli processed?

Answer 35

Auditory cortex located, located in the temporal lobe of the brain.

Question 36

If the auditory nerve is severed, can sound still be detected by conductance through bone?

Answer 36

Conductance through bone allows some hearing by causing the cochlea to vibrate, which stimulates APs that pass through the auditory nerve to the brain. However, if the auditory nerrve is severed, no hearing of any kind is possible. If the bones in the middle ear don't work, some hearing is still detected via bone vibrations.

Question 37

What is the function of the vestibular complex.

Answer 37

The vestibular complex is made of 3 semicircular canals, the utricle, the saccule, and the ampulla. Just like the cochlea, the tubes are essentially filled with endolymph, and they contain hair cells that detect motion. However, their function is not to detect sound, but rather rotational acceleration of the head. They send Balance information to the pons, cerebellum, and other areas.

Question 38

Cornea, refraction, sclera, choriod, retina.

Answer 38

Light enters the eye through the cornea, the clear portion at the front of the eye. Light is bent or REFRACTED as it passes through the corner. The cornea is continuous at its borders with the white of the eye the sclera. Beneath the sclera is a layer called the choroid, which is darkly pigmented cells that absorb excess light within the eye. Beneath the choroid is the surface upon which light is focused, the retina.

Question 39

Anterior chamber, aqueous humor, pupil, posterior chamber, lens. ciliary muscle.

Answer 39

Just inside the corner is the anterior chamber, which contains a fluid termed the aqueous humor. At the back of the chamber is an MB called the iris with an opening called the pupil. The iris is the colored part of the eye, and muscles in the iris regulate the diameter of the pupil. Just behind the iris is the posterior chamber, also containing the aqueous humor. In the back part of the posterior chamber is the lens. The lens focuses light on the retina.

Question 40

What varies the curvature of the lens?

Answer 40

The ciliary muscle varies the curvature of the lens and its refractive power.

Question 41

Vitreous chamber and components.

Answer 41

Contains vitreous humor, chamber from lens to retina.

Question 42

Direction of light from retina to nerve.

Answer 42

Light must pass by two layers of neurons before it can reach the rods and cones. The rods and cones synapses with the bipolar cells (one axon and dendrite). The bipolar cells in turn synapses with ganglion cells, whose axons comprise the optic nerve, which travels from each eye toward the optic nerve.

Question 43

Optic disk/ blind spot.

Answer 43

The point on the retina where many axons from the ganglion cells form the optic nerve is the optic disk. This is the blind spot.

Question 44

Macula and fovea centralis.

Answer 44

The Macula is a special region of the retina. The center of the macula is the fovea centralis (focal point which contains only CONES and is responsible for extreme visual acuity).

Question 45

The protein within rods and cones.

Answer 45

Opsin, which is bound to one molecule of retinal, derived from vitamin A.

Question 46

What does all trans form of the retinal trigger?

Answer 46

Typically in mostly cis, but upon absorbing a photon of light, retinal is converted to the all trans form. This triggers a series of reactions that ultimately closes the Na channels and the cell hyperpolarizes, which decreases glutamate release.

Question 47

What happens to off and on center bipolar cells when its center dark?

Answer 47

Center dark -> cone depolarizes -> glutamate released -> on center hyperpolarizes and NT release decreased -> off center bipolar cell is stimulated, NT release is increased -> firing of ganglion cell starts or is increased.

Question 48

Emmetopia.

Answer 48

normal vision.

Question 49

Myopia and how to correct it.

Answer 49

Nearsightedness is myopia. Too much curvature of the cornea or lens causes the light to bend too much and to be focused in the front of the retina. You correct it via a concave (diverging) lens.

Question 50

Another word for farsightedness and how to correct it.

Answer 50

Hyperopia. Results from focus of the light behind the retina. Corrected by a convex (converging) lens.

Question 51

An inability to accomodate (focus).

Answer 51

Presbyopia. Rsults from loss of flexiblity of the lens, which occurs with aging.

Question 52

Feature detection theory.

Answer 52

Certain areas of the brain are activated when looking at a different things.

Question 53

Parellel processing.

Answer 53

Many aspects of a visual stimulus (such as form, motion, color, and depth) are processed stimultaneously instead of in a step by step or serial fashion.

Question 54

Absolute threshold versus difference threshold.

Answer 54

The minimum stimulus intensity required to activated a sensory receptor 50% of the time. Absolute thresholds are important for detecting the presence of absence of stimuli, but the ability to determine the change or difference is also important. The difference threshold is the min noticeable difference b/t any two sensory stimuli.

Question 55

Signal detection theory.

Answer 55

Attempts to predict how and when someone will detect the presence of a given sensory stimulus ( the signal) amidst all other sensory stimuli in the background.

Question 56

Gestalt principle.

Answer 56

The whole exceeds the sum of its parts. When humans perceive an object, rather than seeing lines, angles, colors, and shadows, they perceive the whole.

Question 57

Bottom-up processing.

Answer 57

Begins with sensory receptors and works up to the complex integration of information occurring in the brain.

Question 58

Top down processing.

Answer 58

When the brain applies experience and expectations to interpret sensory information.

Question 59

Do humans use bottom up or top-down processing?

Answer 59

We use both. Information is received in a bottom-up fashion from sensory receptors while the brain is superimposing assumptions in a top-down manner.

Question 60

Nervous system and endocrine system are two major control systems of the body. But what makes them different?

Answer 60

The nervous sys is fast acting with relatively short-term effects, whereas the endocrine system takes longer to communicate signals but has generally longer lasting effects.

Question 61

Hormone.

Answer 61

A molecule which is secreted into the bloodstream by an endocrine gland, which is a ductless gland whose secretory products are picked up by capillaries supplying blood to the region.

Question 62

Endocrine versus exocrine gland.

Answer 62

Endocrine: ductless gland whose secretory products are picked up by capillaries. Exocrine gland secrete their products into the external environment by way of ducts, which empty into the gastrointestinal lumen or the external world.

Question 63

Autocrine.

Answer 63

Signaling molecules the modify the activity of the cell which secreted them.

Question 64

Peptide hormones and their properties.

Answer 64

1) Peptide hormone are synthesized into the rough ER and are released by exocytosis. In the bloodstream they dissolve in the plasma and thus are required to communicate with the interior of the target cell by way of a second messenger cascade. Their effects expire rapidly - the modify the effects of existing proteins.

Question 65

Two subgroups within the peptide hormone category.

Answer 65

Polypeptide and amino acid deriviatives.

Question 66

Steroid hormones and their properties.

Answer 66

2) Steroid hormones are synthesized from choelsterol in the smooth ER. Steroids can freely disffuse through biological MB. They are not stored. They travel through blood stuck to proteins in plasma, such as albumin. It exerts its effects on targets cells by diffusing through the plasma MB to bid with a receptor in the cytoplasm. Once its bound its ligand, the steroid hormone receptor complex is transported to the nucleus and regulates transcription.

Question 67

Regulation of the endocrine system is ______.

Answer 67

Automatic.

Question 68

Tropic hormones.

Answer 68

Hormones that regulate hormones.

Question 69

Hypothalamus, anterior pituitary, and adrenal cortex. How does it all work for cortisol levels?

Answer 69

The hypothalamus controls the endocrine sys by releasing tropic hormones (like corticotropin-releasing hormone) that regulate other tropic hormones. These are called releasing and inhibiting factors. The role of CRH is to increase the secretion of ACTH (adrenocorticotropic hormone), which stimulates the adrenal cortex to secrete cortisol. Increase in cortisol results in feedback inhibition of ACTH and CRH.

Question 70

The endocrine control center.

Answer 70

Hypothalamic pituitatry control axis.

Question 71

A double capillary bend system that provides efficient transport of hypothalamic releasing and inhibiting factors to the anterior pitutary.

Answer 71

The bloody supply is known as the hypothalamic pituitary portal system.

Question 72

Anterior pituitary/adenohypophysis and its function.

Answer 72

The AP is a normal endocrine gland, and it is controlled by hypothalamic releasing and inhibiting factors.

Question 73

Posterior pituitary/neurohypophysis and its function.

Answer 73

The posterior pituitary is composed of axons which descend from the hypothalamus. These hypothalamic neurons that send axons down to the posterior pituitary are an example of neuroendocrine cells, neurons which secrete hormones into the bloodstream. Hormones of the NP include ADH (kidney retention), oxytocin, which induces milk production and uterine contractions.

Question 74

Thyroid hormones and functions.

Answer 74

Produced from amino acid tyrosine. The production of TH is increased by thyroid stimulating hormone from the anterior pituitary. The effect is to increase metabolism and body temp. Exposure to cold can increase production of thyroid hormone. Thyroid hormones bind to receptors that regulate transcription.

Question 75

Cortisol - where it's produced and its effects.

Answer 75

Cortisol is secreted by the adrenal cortex in response to ACTH from the pituitary gland. The effects of cortisol tend to help the body deal with stress. Mobilizes glycogen and fat stores to privide energy during stress and increase the consumption of proteins for energy.

Question 76

Would an inhibitor of protein synthesis block the acion of thyroid hormones.

Answer 76

Yes. Thyroid hormones bind to a receptor that regualtes transcription. The mRNA produced by the thyroidhormone must be processed and translted before the effects of the thyroid hormone would become evident.