Unit 6: Sensory Systems: Nervous Flashcards

Question

Mechanisms of action of tastes: sugars, alkaloids & glutamates...

Answer 1

bind to receptors

Answer 2

penetrate cells & depolarize them directly

Answer 3

Innervation of the taste buds Cranial nerves VII (Facial), IX (Glossopharyngeal), and X (Vagus) All fibers project to solitary nucleus in medulla Cells project to hypothalamus & amygdala activate autonomic reflexes such as salivation, gagging & vomiting Cells project to thalamus & then postcentral gyrus of the cerebrum conscious sense of taste

Answer 4

1. Nerves that carry taste signals Taste buds send signals through three main cranial nerves: VII (Facial) – handles the front of the tongue IX (Glossopharyngeal) – handles the back of the tongue X (Vagus) – handles taste from the throat area 2. First stop: Solitary nucleus in the medulla All these taste signals go to the solitary nucleus in the medulla (part of the brainstem). Think of it as the brain’s "taste relay station." 3. Split into two main pathways from there: Pathway 1: To the hypothalamus and amygdala This part deals with automatic reactions to taste—like drooling (salivation), gagging, or even throwing up (vomiting). These areas also connect taste to emotions and memories. Pathway 2: To the thalamus and then the postcentral gyrus This is the pathway for the conscious experience of taste—what you’re actually aware of when you say, "This tastes sweet" or "That’s spicy." The postcentral gyrus is the part of your brain that lets you feel things—including taste.

Answer 5

Quick Memory Trick "VII, IX, X taste the mix" → The 3 nerves that carry taste "Medulla is the middleman" → All signals go there first "One path for reflex, one for awareness" Reflex = Hypothalamus & amygdala (automatic stuff) Awareness = Thalamus → Postcentral gyrus (conscious taste

Answer 6

Olfactory cells -neurons with 20 cilia called olfactory hairs binding sites for odor molecules in thin layer of mucus -axons pass through cribriform plate -survive 60 days

Answer 7

Odor molecules must be volatile bind to a receptor on an olfactory hair triggering the production of a second messenger opens the ion channels & creates a receptor potential Receptors adapt quickly due to synaptic inhibition in the olfactory bulbs Bulb cells form the axons of the olfactory tracts lead to temporal lobe, amygdala, hypothalamus emotional responses to odors cough, salivate, sneeze or vomit in response to odors

Answer 8

🧠 How Smell Works – Made Simple Odor molecules must be in the air They have to be volatile (able to float in the air) to be smelled. Odor hits olfactory hairs (tiny sensors in your nose) The molecule binds to a receptor, which sends a signal inside the cell (called a second messenger). Signal opens doors (ion channels) This creates an electrical signal—your brain’s way of saying “Hey, there's a smell!” Smell sensors get used to odors fast Your brain adapts quickly through synaptic inhibition, which is why you stop noticing a smell after a few minutes. Olfactory bulbs send the signal to the brain Special brain cells form the olfactory tracts, which carry the smell signal to important areas: Temporal lobe – helps you recognize the smell Amygdala & hypothalamus – control emotional and physical reactions Smells can cause strong reactions Certain odors can make you cough, salivate, sneeze, or even vomit—this is your brain reacting automatically. 🧠 Memory Trick “Smell travels: Hair → Bulb → Brain → Reaction” “Smells trigger feelings fast” – because they go straight to emotional centers in the brain.

Answer 9

Sound is any audible vibration of molecules Vibrating object pushes air molecules into eardrum making it vibrate

Answer 10

👂 How Hearing Works – Step by Step Sound hits your eardrum (tympanic membrane) The eardrum vibrates when sound waves reach it—like a drum being hit. Vibration moves tiny ear bones (auditory ossicles) These 3 bones in the middle ear (hammer, anvil, stirrup) pass the vibration along. Vibration reaches the inner ear (cochlea) The movement travels to the cochlea, a snail-shaped part full of fluid. Cochlear (basilar) membrane vibrates Inside the cochlea, this membrane shakes, activating hair cells (your hearing sensors). Hair cells send signals to your brain When hair cells bend, ion channels open and send an electrical signal—this is how your brain “hears” the sound. Tympanic reflex = built-in ear protection Loud noise? Muscles in your ear tighten the bones to protect your inner ear (cochlea) from damage. 🧠 Memory Tip “Sound → Eardrum → Bones → Cochlea → Brain” “Hair cells hear” “Reflex protects” from loud sounds

Answer 11

Temporal lobe (primary auditory cortex) is site of conscious perception

Answer 12

Auditory (Eustachian) tube

Answer 13

-Air-filled cavity in temporal bone separated from air outside the head by tympanic membrane -also contains auditory ossicles (malleus, incus, stapes)

Answer 14

-Sound is produced by vibration of ossicles and then vibration of basilar membrane under hair cells. -Can happen as often as 20,000 time per second

Answer 15

🎧 How Hair Cells Turn Sound into Signals – Step by Step Stereocilia are soaked in potassium (K⁺) These little hair-like structures on top of hearing cells sit in fluid with a lot of K⁺, which sets up a strong energy difference (like a battery). Sound bends the stereocilia When the basilar membrane vibrates (because of sound), it makes the stereocilia bend. Bending pulls on tiny “tip links” These tip links are like little ropes that open up doors (ion channels) when stretched. Potassium (K⁺) rushes in Because of the energy difference, K⁺ flows into the cell, making it more positive (depolarization). This triggers neurotransmitter release The depolarized hair cell releases chemicals (neurotransmitters) that send a signal to nearby nerve endings. 🧠 Memory Tricks “Bend → Pull → Open → Flow → Signal” Or: “Sound bends hair → K⁺ enters → Signal sent to brain

Answer 16

Crista ampullaris consists of hair cells buried in a mound of gelatinous membrane (one in each duct) Orientation of ducts causes different ducts to be stimulated by rotation in different planes

Answer 17

Conjuctiva highly innervated and vascular mucous membrane that lines the eyelids and covers most of eyeball

Answer 18

Lacrimal apparatus produce tears wash away foreign particles, aid diffusion of gases and contain lysozyme

Answer 19

-Fibrous layer = sclera and cornea protection -Vascular layer = choroid, ciliary body and iris nutritive support -Sensory layer = retina and optic nerve receive and process light information

Answer 20

Series of transparent structures that bend light rays to focus them on the retina 1)cornea is transparent covering 2)aqueous humor is clear serous fluid filling area between lens and cornea 3) lens is suspended by suspensory ligaments --capable of changing shape to help focus light rays 4) vitreous humor is jelly filling the space between the lens and retina

Answer 21

Optic disk or blind spot is where optic nerve exits the posterior surface of the eyeball -no receptor cells are found in optic disk

Answer 22

Visual filling is the brain filling in the green bar across the blind spot area

Answer 23

👁️ How the Eye Forms an Image (with Autonomic Control) Light bends (refraction) as it passes through eye structures This helps focus the image clearly. Light passes through the eye’s optical parts (Cornea → aqueous humor → lens → vitreous humor) to form a tiny, upside-down image on the retina. Muscles in the iris control pupil size (light entry) Pupillary constrictor (circular muscle): Makes the pupil smaller (in bright light) Controlled by the parasympathetic nervous system Pupillary dilator (radial/spoke-like muscle): Makes the pupil larger (in dim light or during fight-or-flight) Controlled by the sympathetic nervous system 🧠 Memory Tips “Light bends → Image on retina (upside-down)” “Constrictor = Parasympathetic = Peace/light” “Dilator = Sympathetic = Stress/dark”

Answer 24

👁️ Focusing the Eyes – Far vs. Near When looking at something far away: Light rays are parallel, so the eye focuses easily—no extra effort needed. When looking at something up close (Near Response): The eyes make three adjustments to see clearly: Convergence of the eyes Both eyes turn inward to focus on the same close object. Constriction of the pupil The pupil gets smaller to block out side (peripheral) light, which helps sharpen the image and reduce blur. Accommodation of the lens The ciliary muscle contracts, loosening the suspensory ligaments. This allows the lens to become rounder (more convex) to bend light more and focus on the close object. 🧠 Memory Trick “Far = Easy, Near = Three” (For far: no effort. For near: 3 steps – converge, constrict, accommodate)

Answer 25

Behavior of eyes when focused on distant object (over 20 ft away) and onto close object In emmetropia (normal vision): When looking at distant objects, the light rays entering your eye are parallel. A healthy, properly-shaped eye focuses those parallel light rays directly on the retina — no extra effort needed from the lens. So, emmetropia = perfect focus of parallel light from a distance. 🧠 Quick Summary: Emmetropia is about the eye's ability to naturally focus parallel (distant) light rays onto the retina. That’s why distant objects appear clear without the need for focusing effort or correction.

Answer 26

Hyperopia is farsighted (eyeball too short) correct with convex lenses

Answer 27

Myopia is nearsighted (eyeball too long) correct with concave lenses

Answer 28

emmetropia (normal vision): When looking at distant objects, the light rays entering your eye are parallel. A healthy, properly-shaped eye focuses those parallel light rays directly on the retina — no extra effort needed from the lens. So, emmetropia = perfect focus of parallel light from a distance.

Answer 29

Sensitivity of rods in dim light -extensive neuronal convergence -600 rods converge on 1 bipolar cell -many bipolar neurons converge on each ganglion cell Edges of retina with widely spaced rod cells is low-resolution system only alerting us to motion

Answer 30

Fovea contains only 4000 tiny cone cells and no rods -no neuronal convergence -each cone cell has “private line to the brain” High-resolution vision, but little spatial summation and less sensitivity to light intensity

Answer 31

Color Vision Basics Primates have excellent color vision They can see a wide range of colors. Nocturnal animals (like some vertebrates) Only have rods, which help them see in low light, but don't detect color. Cones in the eyes Cones are named after the color they absorb: Blue cones Green cones Red cones Color perception Your brain creates color by mixing the signals from all three types of cones. Color blindness This happens when someone is missing one of the color-detecting photopsins (the proteins in cones). Red-green color blindness is the most common, where the person can’t tell the difference between red and green. This happens if they lack either the red or green cones. Color blindness is hereditary It’s a sex-linked recessive trait, meaning 8% of males have it (since they only have one X chromosome). 🧠 Memory Trick “Primates = Color vision, Nocturnal = Just rods” “Color blindness = Missing a cone”

Answer 32

Neural apparatus includes the retina and optic nerve Retina forms as an outgrowth of the brain -attached only at optic disc where optic nerve begins and at its front edge -pressed against rear of eyeball by vitreous humor Detached retina blow to head or lack of sufficient vitreous humor leads to blindness due to disruption of blood supply no longer close to choroid

Answer 33

Heat/Temperature

Answer 34

Physical change (pressure, touch, sound waves)

Answer 35

Inside the body

Answer 36

Body Position

Answer 37

Harmonious

Answer 38

near surface of the body

Unit 6: Sensory Systems: Nervous Flashcards

(72 cards)