Unit 2 Study Guide Questions

Question 1

physiological sensory processing, driven by sensation

Answer 1

Bottom-up processing

Question 2

perception is driven by cognition

Answer 2

Top-down processing

Question 3

Olfactory Transduction Pathway

Answer 3

inhale odorants –> bind to olfactory receptors (on cilia) –> trigger cell changes –> action potential down axon –> project info about pattern of activation to olfactory bulb –> bypasses thalamus –> some info goes to amygdala and hypocampus; some info goes to olfactory cortex where messages coded by location –> perceptions of different smells

Question 4

Taste Transduction Pathway

Answer 4

tastants enter taste pores (taste bud openings) in oral cavity –> interact with taste receptors –> taste nerves on each side of tongue (chorda tympani, glossopharyngeal, greater superficial petrosal, superior pharyngeal) –> solitary nucleus (in brain stem) –> crosses over to other side of brain –> ** thalamus** –> gustatory cortex

Question 5

What are the four taste nerves?

Answer 5

• chorda tympani
• glossopharyngeal
• superior laryngeal
• greater superficial petrosal

Question 6

Vision Pathway

Answer 6

light hits pupil–> focused by lens and cornea onto –> rods and cones at back of retina –> reduces NT release, hyperpolarizes receptor –> passes through horizontal/bipolar/amacrine cells –> ganglion –> produce action potentials –> down axon via optic nerve –> leave eye through optic disk –> half of axons from each eye cross to other side of brain at optic chiasm –> portion of axons synapse in lateral geniculate nucleus (in thalamus); the rest go to primary visual cortex (in occipital lobe)

Question 7

Auditory Pathway

Answer 7

Air to pinna –> through ear canal –> sound waves vibrate tympanic membrane –> ossicles (malleus, incus, stapes) amplify sound waves –> vibrations through cochlea’s fluid-filled tunnels (scala vestibule, scala tympani, cochlear duct) –> excite auditory nerve –> hair cells/receptors (receptors) move due to tectorial membrane (mechanical stimulation) –> ion channels open –> depolarization due to influx of K+ –> GLUT and ACh released to cochlear nerve afferents –> crosses midline at cochlear nucleus –> superior olivary nucleus –> inferior colliculus –> medial geniculate nucleus –> auditory cortex

Question 8

Somatosensory pathway

Answer 8

Skin/touch receptors send action potentials –> unipolar axon (in dorsal root ganglion) –> enter spinal cord dorsal horn –> joins dorsal column in spine –> in medulla, periphery axon makes synapse to neuron of dorsal column nuclei –> sends axon across midline –> up to thalamus –> thalamus receives info contralaterally –> send info to primary somatosensory cortex

Question 9

particular neurons that are, right from the outset, labeled for distinctive sensory experiences

Answer 9

labeled lines

Question 10

region of space in which stimulus will alter neurons’ firing rate

Answer 10

receptive field (why photoreceptors only transmit info as light)

Question 11

progressive loss of receptor response as stimulation is maintained

Answer 11

sensory adaptation

Question 12

recept in which frequency of action potentials drops rapidly as stimulation is maintained

related to sensory adaptation

Answer 12

phasic receptor

Question 13

receptor in which frequency of action potentials declines slowly or not at all as stimulation is maintained

Answer 13

tonic receptors

Question 14

Pain Pathway

Answer 14

Damaged cells release substances –> stimulate nociceptors –> action potentials in periphery –> excite blood cells and mast cells/produce inflammation/ mast cells release histamine –> info from periphery enters through **dorsal root ** and synapses on neurons in dorsal horn –> pain fibers release glutamate NT and substance P neuromodulator in spinal cord –> then dorsal horn cells send info across midline and up to thalamus –> form spinothalamic system (different than somatosensory)

In spinothalamic pathway:

Nerve fibers send axons into dorsal horns of spinal cord  synapse on spinal interneurons  project across midline  ascend to thalamus

Question 15

Hypovolemic thirst pathway

Answer 15

triggered when fluid volume is low

cardiac baroreceptors –> via vagus nerve –> brain stem –> Preoptic Area (POA)–>

kidney baroreceptors –> angiotensin II restricts blood vessels, reabsorbs water –> subfornical organ –> Preoptic Area (POA) –>

From Preoptic Area (POA) –> paraventricular and supraoptic nucleus –> vasopressin –> water conservation

From Preoptic Area (POA) –> Hypothalamic thirst network –> drinking behavior

Question 16

Osmotic thirst pathway

Answer 16

triggered when solute concentration is too high

Osmosensory neurons in OVLT –> POA –>
- hypothalamic thirst pathway –> drinking behavior
- paraventricular and supraoptic nucleus –> vasopressin –> water conservation

Question 17

Hunger hormones

Answer 17

leptin: in fat cells, provide info about long-term energy stores
ghrelin: in stomach; appetite stimulant
PYY3-36: in intestines; appetite suppressant
Cholecystokinin: in gut; acts on vagus nerve to inhibit appetite

Question 18

When blood sugar is low, signals release of ——-

Explain cycle.

Answer 18

glucagon

glucodetectors in liver recognize low blood sugar –> signal *glucagon release from pancreas –> breaks down glycogen to glucose (glycogenolysis) –> released into circulatory system –> raises blood sugar

Question 19

When blood sugar is high, signals release of ——-. Explain cycle.

Answer 19

insulin

glucodetectors in liver detect high blood sugar –> pancreas releases insulin –> helps get glucose into cells (acts as receptor “key”) AND signals liver to store excess glucose as glycogen (glycogenesis) –> lowers blood sugar in circulation

Question 20

Thermoregulatory system for mammals

Answer 20

Thermoreceptors (TRP receptors) in skin, body core, hypothalamus detect temp and transmit info –> spinal cord –> brainstem –> hypothalamus

Body temp outside of set zone?
neural regions initiate physiological and behavioral responses to return temp to set zone

Physiological:
- increase temp: shiver, fluff out fur, decrease blood flow to skin
- decreatse temp: pant, sweat

Behavioral:
- increase or decrease temp: change exposure of body surface, change insulation, change surroundings

Question 21

Hunger in hypothalamus (brain lesions)

Answer 21

VMH lesion: caused obesity due to increase in food intake; thought to be satiety center

LH lesions: caused weight loss due to refusal to eat; thought to be hunger center

BUT weight/eating went back to normal after awhile = neither VMH or LH is solely responsible for appetite signaling

Question 22

Neither —– or —- is completely responsible for hunger or satiety.

Answer 22

LH or VMH

Question 23

——– drive hypothalamic appetite control

How?

Answer 23

hormones

• arcuate nucleus circuit integrates hormones
• digestive organs and fat tissue release hormonal signals (energy balance)

Question 24

What do neurotrophins do?

Answer 24

• axon guidance
• cell growth/survival
• stimulate synaptogenesis

Question 25

How do bird brains change from breeding to non-breeding seasons?

Answer 25

HVC and Area X = important for male songbirds to learn/maintain mating longs In non-breeding season: - HVC neurons are less active In breeding season: - HVC neurons are more active and lead to larger HVC brain area during breeding When birds no longer need those songs, those areas die off -- neurogenesis is done better in these birds

Question 26

CNS Divisions Early in Development

Answer 26

18 days: - 3 cell layers are ectoderm (skin, neural tissue), mesoderm (skeletal, cardia), endoderm (digesting, respiratory) - thickening of dorsal surface tissue (ectoderm) develops neural plate 20 days: - neural plate starts to fold in to make neural groove 22 days: - neural tube forms when neural groove closes (beginning of CNS) - neural tube = spinal cord - anterior end = brain 25 Days: - spinal cord and 3 brain divisions (forebrain, midbrain, hindbrain) are discernable 50 days: - from forebrain, 5 main divisions of brain become visible (cortex, basal ganglia, limbic, thalamus, hypothalamus) 100 Days: - cerebral hemispheres more developed - hindbrain is differentiated into cerebellum, pons, medulla

Question 27

Explain divisions of CNS at 25 days.

Answer 27

**spinal cord** - formed from neural tube **forebrain**(front of neural tube) - Telencephalon = cerebral hemispheres - diencephalon = thalamus and hypothalamus **midbrain** - middle of neural tube **hindbrain** (rear of neural tube) - cerebellum, pons, medulla

Question 28

What are the three classes of hormones?

Answer 28

proteins, amines (or peptides), steroids

Question 29

Explain tropic hormones.

Answer 29

**Hypothalamus** *regulates release of **tropic hormones*** by *sending "**releasing hormones"*** to **anterior pituitary** --> **endocrine cells in pituitary** *make/release **tropic hormones*** --> hormones *enter circulation*, *affect endocrine organ secretion throughout body*

Question 30

Explain gonadal hormone release.

Answer 30

hypothalamus controls gonadal hormone release via anterior pituitary (brain/pituitary regulation) **Hypothalamus** releases ***GnRH*** --> stimulates **anterior pituitary** to release ***tropic hormones*** (LH, FSH) --> enter **circulatory system** --> stimulate **gonads** to release ***gonadal hormones*** (testosterone, estrogen, progesterone)

Question 31

Endocrine feedback loops work secrete hormones through either ----- regulation or ----- and ------- regulation hormone release in both systems is regulated by ------ cells

Answer 31

neuroendocrine

Question 32

How are the two types of regulation in endocrine feedback loops different?

Answer 32

brain regulation -- biological response in target tissue tells hypothalamus to shut down brain and pituitary regulation -- circulating hormones in blood stream tell hypothalamus to shut down

Question 33

Sexual Differentiation in Bird Brains

Answer 33

looks at organizational effects of steroid hormones Takeaways before looking at genetics: - Area X, HVC, and RA are all larger with more dense/larger neurons in males. These difference give us male vs. female brain. - significant differences in brain area size, neuron size, # of neuron - cannot create male-typic brain in female by altering hormones - estrogen masculinizes better than testosterone - blocking estrogen has no significant effect on masculizination of brain in males or females Genetic role (using gynandromorph) - test genetics + hormones - in gynandromorph, genetic sex differences only act on one side, hormones act on both sides - takeaway: **genetically male side is more "male typic" than female side. This means combo of genes/hormones (epigenetics) contribute to sex diff early in prenatal development**

Question 34

Which gene is responsible for sex dimorphism in humans?

Answer 34

SRY

Question 35

more than two sizes of gametes

Answer 35

anisogametic

Question 36

only one gamete size

Answer 36

isogametic

Question 37

two sizes of gametes but no sex dimorphisms (both males and females pass on both sizes of gametes)

Answer 37

monecious

Question 38

no fusion of gametes or combination of chromosomes; genetic info directly passed on from parent

Answer 38

Asexual reproduction

Question 39

some individuals have no gametes

Answer 39

infertility

Question 40

XXY genes

Answer 40

Kleinfelter syndrome

Question 41

X0 gene (no Y gene)

Answer 41

Turner syndrome

Question 42

XX but male phenotype

Answer 42

De la Chappelle

Question 43

XY but female phenotype, including fertility

Answer 43

Sawyer Syndrome

Question 44

Why are multiples no longer an issue in in vitro fertilization?

Answer 44

PGT testing

Question 45

Diurnal Cortisol release

Answer 45

Wake up: cortisol peaks throughout day: declines Evening: steady Next morning: peaks again, restarts

Question 46

Diurnal testosterone release

Answer 46

- hormone levels vary within day - hormone amount changes with age - diurnal pattern of hormone changes with age (is less variable)

Question 47

hormonal variation in women

Answer 47

Menstrual cycle = hormone release pattern over several weeks instead of one day Pregnancy = hormone release pattern over several months

Question 48

Epigenetics and effect on development

Answer 48

Study #1: Black6 mice raised/carried by either Albino or Black6 mom; groups: - carried/raised by Albino mom: acted more like Albino male (explored less, slower mazes, more anxious) - carried by Albino mom but raised by Black6: acted somewhat like albino males (more anxious, slower at mazes) - carried by Black6 mom but raised by Albino: acted more like Black6 males but still were more anxious (like albino males) **Black6 male mice were genetically identical, so changes have to be due to prenatal environments and postnatal experiences. Type of mothering received influenced gene expression. ** Rodent Methylation study attentive rodent mother prevent methylation of stress hormone receptor gene in offspring (leading to lower stress hormones, low anxiety, high licking/grooming) --> female offspring grew to be attentive mothers themselves. Effect can be carried across generations. - in humans, same gene more likely to be methylated in suicide victims but only those who experienced child abuse

Question 49

Sympathetic nervous system prompt you to rehydrate through ------- and -------.

Answer 49

thirst; salt hunger

Question 50

What does aldosterone do?

Answer 50

in thirst system, signals **kidneys to conserve sodium** and aid in water retention

Question 51

What does angiotensin II do?

Answer 51

increases blood pressure

Question 52

Osmosensory neurons in OVLT relay information to -------------- and -----------------, and control rate at which posterior pituitary releases -------------.

Answer 52

supraoptic nucleus, paraventricular nucleus, vasopressin

Question 53

What does vasopressin do in thirst pathway?

Answer 53

raises blood pressure (constricts blood vessels) and helps kidney absorb water

Question 54

How does entrainment of SCN cells happen? | different than melatonin

Answer 54

- system is triggered by binding of glutamate receptors - retinal ganglion cells signal SCN (helps entrain/set clock)

Question 55

How is melatonin production triggered?

Answer 55

SCN is entrained by light/dark and regulates pineal gland secretion of melatonin.

Question 56

How is entrainment of SCN cell (partially) triggered?

Answer 56

retinal ganglion cells **(ipRCGs)** detect light --> glutamate released ---> binds to SCN neurons --> Per is stimulated Within cell: - Clock and cycle form a dimer and enter nucleus to - tell per and cry genes to make per and cry proteins - per and cry proteins bind and - inhibit Clock/Cycle dimer (negative feedback system) - Per/cry proteins break down over time - when Per/cry no longer active, Clock/Cycle dimer reforms and system restarts

Question 57

What do ipRCGs do?

Answer 57

(intrinsically photosensitive ganglion cells) light stimulates ipRCGs --> signals SCN and other brain areas to send signals through rest of body works through retinohypothalamic pathway - ipRCGs (contain light-sensitve melanopsin) carry light from eye to SCN. **This is pathway for entraining to light or dark.** - light suppresses melatonin production; ipRCGs signal SCN to send message to pineal gland to produce melatonin

Question 58

What parts of brain keep us awake?

Answer 58

- pontomesencephalon (projects to thalamus, basal forebrain, hypothalamus): releases ACh (wake) and glutamate (wake) - locus coeruleus (in pons) - typically dormant during sleep but releases GABA and glycine which inhibit movement during REM - hypothalamus - releases histamine (wake) - basal forebrain - releases ACh (wake) but also releases GABA (sleep)

Question 59

During REM there is low blood flow in --------------------------.

Answer 59

inferior frontal cortex

Question 60

Theories for sleep

Answer 60

- restorative (metabolism and waste removal) - energy conservation - learning and memory (do synaptogenesis/pruning happen in sleep)