a&p 1 lecture exam 3

What is the difference between general and special sensations?

General sensations are distributed throughout the body (e.g., pain, temperature), while special sensations are localized to specific organs (e.g., vision, hearing).

How does sensation differ from perception?

One is the detection of stimuli, the other is the conscious interpretation of those stimuli.

What distinguishes simple from complex receptors?

Simple receptors are free nerve endings; complex receptors are specialized structures or cells.

What determines receptor specificity?

The structure and function of the receptor determine what type of stimulus it can detect.

What determines sensory acuity?

The density of receptors and the size of their receptive fields.

What is a generator potential?

A graded depolarization caused by a stimulus that can lead to an action potential.

Define transduction.

The conversion of a stimulus into an electrical signal.

What is the sensory threshold?

The minimum stimulus intensity required to produce a response.

What encodes stimulus intensity?

The frequency of action potentials.

What encodes stimulus location?

The specific location of the activated receptors.

What encodes stimulus modality?

The type of receptor and its pathway to the brain.

How is two-point discrimination assessed?

By measuring the minimum distance at which two stimuli are felt as separate.

What does two-point discrimination evaluate?

Sensory receptor density and acuity.

What is adaptation in sensory receptors?

A decrease in receptor sensitivity to a constant stimulus.

Where does adaptation occur and why?

In phasic receptors to prevent overload from constant stimuli.

What is the difference between tonic and phasic receptors?

Tonic receptors respond continuously; phasic receptors adapt quickly and respond at stimulus onset or offset.

What are interoceptors?

Receptors that monitor internal conditions.

What are exteroceptors?

Receptors that detect external stimuli.

What are proprioceptors?

Receptors that monitor body position and movement.

What receptor detects pain?

Nociceptors.

What receptor detects temperature?

Thermoreceptors.

What receptor detects pressure and vibration?

Mechanoreceptors.

What receptor detects chemicals?

Chemoreceptors.

What is the difference between fast and slow pain?

Fast pain is sharp and localized; slow pain is dull and diffuse.

Where do chemoreceptors monitor blood?

In the carotid and aortic bodies.

Where are other chemoreceptors found?

In the medulla oblongata and brainstem.

Where are baroreceptors found?

In blood vessels, lungs, and digestive and urinary tracts.

What is the difference between fine and crude touch?

One is detailed and localized; other is general and poorly localized.

What is the function of a Merkel disc?

Detects light, sustained touch.

What does a Ruffini corpuscle detect?

Deep, sustained touch.

What does a Meissner’s corpuscle detect?

Low-frequency vibrations.

What does a Pacinian corpuscle detect?

High-frequency vibrations.

What detects hair shaft movement?

Hair root plexus.

What monitors muscle stretch?

Muscle spindles

What monitors muscle tension?

Golgi tendon organs.

Where are first-order neurons located?

In dorsal root or cranial ganglia; they transmit impulses from receptors to the CNS.

Where are second-order neurons located?

In the spinal cord or brainstem; they relay impulses to the thalamus.

Where are third-order neurons located?

In the thalamus; they carry signals to the sensory cortex.

What are upper motor neurons?

Neurons in the motor cortex or brainstem that influence lower motor neurons.

What are lower motor neurons?

Neurons that directly innervate skeletal muscles.

Name the three somatic sensory pathways.

Posterior column-medial lemniscus, spinothalamic, and spinocerebellar tracts.

What causes phantom pain?

Sensory neurons from the amputated region are still active or misinterpreted.

What causes referred pain?

Visceral pain is perceived as originating from skin due to shared pathways.

What relays visceral sensations?

The solitary nucleus in the brainstem

What is the pyramidal tract?

A tract that controls voluntary motor activity.

What is the extrapyramidal system?

A system for subconscious motor control and coordination.

What is the function of the vestibulospinal tract?

Regulates balance and muscle tone.

What is somatotopy?

The spatial organization of sensory and motor areas corresponding to body regions.

What does the sensory homunculus map?

Sensory input from different body regions; larger areas mean more sensory receptors.

What does the motor homunculus map?

Motor control of body regions; larger areas reflect finer motor control.

Describe the composition of each layer of the olfactory mucosa.

Includes olfactory epithelium (with receptors) and lamina propria (with glands, blood vessels, nerves).

Describe the process of olfaction.

Odorants bind to receptors, triggering action potentials sent via CN I to the olfactory cortex.

You smell an apple pie. This sensation was carried by CN .

CN I (Olfactory).

You smell bleach, and your nose burns. This sensation was carried by CN .

CN V (Trigeminal).

is the only sensation that bypasses the thalamus to reach conscious awareness.

Olfaction.

Describe the structure of a taste bud.

Composed of gustatory cells, basal cells, and supporting cells within lingual papillae.

Describe the locations of lingual papillae.

Fungiform (anterior), circumvallate (back), foliate (sides), filiform (no taste buds).

Which lingual papillae lack taste buds?

Filiform papillae.

What are the five primary taste sensations?

Sweet, salty, sour, bitter, umami.

Describe the gustatory pathway.

Taste receptors → cranial nerves → medulla → thalamus → gustatory cortex.

You taste salt on the anterior 2/3 of tongue. This sensation was carried by CN .

CN VII (Facial).

You taste salt on the posterior 1/3 of tongue. This sensation was carried by CN .

CN IX (Glossopharyngeal).

You eat a chili pepper, and your mouth burns. This sensation was carried by CN .

CN V (Trigeminal).

You take a drink and taste water. This sensation was carried by CN .

CN X (Vagus).

Humans can discriminate approximate odors.

10,000.

Humans can discriminate approximate tastes.

2,000.

Olfactory sensitivity with age.

Decreases.

Gustatory sensitivity with age.

Decreases.

Olfactory receptors adapt ___.

Rapidly

List the primary taste sensations (exclude umami) from most to least sensitive.

Bitter > sour > salty = sweet.

List the structures of the lacrimal apparatus in order.

Lacrimal gland → ducts → puncta → canaliculi → sac → nasolacrimal duct.

List the layers of the eyeball from outermost to innermost.

Fibrous (sclera/cornea), vascular (choroid), neural (retina).

Describe the pupillary light reflex in low-intensity light.

Pupils dilate via sympathetic stimulation.

Describe the pupillary light reflex in high-intensity light.

Pupils constrict via parasympathetic stimulation.

Describe the arrangement of cells in the retina.

Ganglion cells → bipolar cells → photoreceptors (rods/cones).

Describe the differences between rods and cones.

Rods: light/dark, peripheral; Cones: color, sharp vision.

Describe the circulation of aqueous humor.

Produced by ciliary body → anterior chamber → drains via canal of Schlemm.

What is the function of a convex lens?

Converges light rays.

What is the function of a concave lens?

Diverges light rays.

The image projected onto the retina is , , and .

Inverted, smaller, reversed.

What are the conditions for clear vision?

Light must focus on retina.

What causes astigmatism?

Irregular curvature of the cornea or lens.

What happens to the ciliary muscles during near vision?

They contract.

What happens to the lens shape during distant vision?

It flattens.

What happens to the converging power during near vision?

It increases.

What happens to focal point during distant vision?

It moves further away from lens.

What happens to focal distance during distant vision?

It increases.

What happens to parasympathetic stimulation during near vision?

It increases.

The accommodation reflex describes [near/distant] vision.

Near vision.

What causes myopia and how is it corrected?

Eye too long; corrected with concave lenses.

What causes hyperopia and how is it corrected?

Eye too short; corrected with convex lenses.

How are PRK and LASIK similar?

Both reshape the cornea.

How do PRK and LASIK differ?

LASIK preserves the outer layer; PRK removes it.

How is visual acuity rated?

By comparing to standard 20/20 vision chart.

What does 20/30 vision mean?

You see at 20 feet what normal vision sees at 30 feet.

Describe the structure of a photoreceptor.

Outer segment (discs), inner segment, cell body, synaptic terminal.

What are visual pigments made of?

Opsin + retinal.

How do visual pigments vary in rods and cones?

Rods have rhodopsin; cones have specific opsins for red, green, blue.

Explain trichromatic theory.

Color vision results from stimulation of three types of cones.

What causes color blindness?

Deficiency in one or more cone types.