ANS 315 quiz 4 general slide info

Nervous system 2, sensory receptors

Special Senses rely on?

receptors
in head region

What are the general senses

1. pain

2. temperature

3. pressure

4. touch

What are the special senses?

1. Sight

2. hearing

3. taste

4. smell

5. orientation in space

What do sensation result from?

Stimuli that initiate afferent (toward CNS) impulses

Where is sensory information processed/interpreted at? What does it turn into?

cerebral cortex, a nerve impulse

True or false. Sensory experiences involve receptors.

true

What are the simplest receptor organs.

Bare nerve endings

What are the three different types of sensory receptors?

1. Exteroceptors

2. interoceptors

3. proprioceptors

Function of exteroceptors?

Detect stimuli near external body surface

function of interoceptors?

Detect stimuli from internal environment

Function of proprioceptors?

Detects position and movement of the body

What does exteroceptors detect?

cold, warmth, touch, pressure and special senses

What do receptors adapt to during touch?

sustained stimulation. Receptors cease firing after initial activity (refractory). When stimulus is removed, receptor again responds by firing to signal beginning and ending of stimulus.

Interoceptors detect visceral organs and their function like?

pH, distension, spasm, flow

Describe referred pain

discomfort felt in a body part distinct from the actual source of injury, caused by nerves sharing pathways that confuse the brain.

Referred pain occurs because most ….. sensations are not well …..

visceral, localized.

where can referred pain originate

location of cutaneous and visceral pain afferent fibers on the same neuron in the sensory pathway

What are two examples of referred pain

1. traumatic pericarditis-hardware producing sensitivity in sternum

2. angina pectoris-heart attack in humans

Where are proprioceptors located

joints, muscles, tendons and skin.

What provides information on orientation in space, movement and pressure.

proprioceptors

Describe the fibers of proprioceptors

fibers are heavily myelinated with few synapses for rapid transmission

True or false The body uses reflexes to communicate with its
environment and maintain homeostasis

True

Sensory activation occurs when

a stimulus activates a sensory receptor, sending a neural signal

Body responds to sensations of ……,
…… changes, pressure and touch to
maintain …..

pain, temperature, homeostasis

Why does Response depends on the presence of receptors

May be free nerve endings, some receptors adapt to stimuli.

Which would have more receptors, the tip of a paw or the middle of the hindquarters

paw

Visceral sensations can be difficult to localize
because of skin sensations synapsing at nearby
locations on the

spinal cord

Why does proprioception allow animals to maintain orientation

heavily myelinated fibers and few synapses

What is olfaction

sense of smell

Where is the olfactory epithelium located

in roof of nasal cavity

Describe the receptors of the olfactory epithelium

bipolar neurons with dendrites and axons

Role of cilia in olfaction

detect odors causing receptor potential in receptor cells

What are supporting cells in olfaction

columnar epithelium

what detects volatile chemicals in solution

chemical sense

when are basal stem cells between supporting cells replaced

1x month

Describe the physiology of olfaction

odor-causing chemicals dissolve in mucus membrane. Bind to protein receptors on the cilia to activate second messengers.

Secondary messengers of olfaction

G proteins, activation of adenylate cyclase, production of cAMP, Influx of Na+ to cause depolarization and production of potential.

How does the olfactory communicate with brain

olfactory neurons project to hypothalamus, limbic areas.

what are olfactory nerves

unmyelinated axons (cranial nerve 1)

Describe function of facial nerve (cranial nerve VII)

innervates olfactory glands, can result in stimulation of lacrimal glands and nasal mucous glands.

What is gustation

sense of taste

What is the tongue composed of and what is its function

bundles of muscle fibers, mixing and moving food for swallowing.

What are the 4 shapes of papillae (a-d)

a-fililform: mechanical

b-fungiform: mechanical, gustatory

c-foliate: gustatory

d-vallate: gustatory

What determines taste and what do taste buds allow

papilla: up to hundreds on taste buds. allow animals to differentiate between nutritious and toxic feeds.

describe the stimuli to taste receptors

Sweet taste: binding of sweet tastant to receptor. Excitation of sensory neurons by neurotransmitters.

Are there a high number or low number of receptors in the eye

high

what is a major sense organ with strong stimulation

vision

what is dedicated to vision

a large portion of cerebral cortex

True or false. vision varies among species in perfect of body weight composed by eyes

true, about 50% of head in birds

describe role of eyelids

protect eye and provide lubrication

domestic species have

3rd eyelid

role of eyelashes, eyebrows

protection

What are lacrimal glands

produce lacrimal fluid of water, salts, mucus, antibodies and lysozyme. (cold, wet noses)

Describe the muscles of the eye

six striated muscles outside the eyeball. Lateral, medial rectus, superior, inferior rectus, inferior and superior oblique

What are the three layers of the eyeball

1. fibrous tunic

2. vascular tunic

3. retina

Which layer is the outside layer of the eyeball

fibrous

What is the cornea

transparent layer, curved. in the fibrous tunic.

What makes up the cornea ( 3 layers)

Stratified squamous epithelium in outer layer. collagen fibers, fibroblast in the middle layer. Simple squamous epithelium in the inner layer.

What is sclera and what is its role

dense connective tissue to provide rigidity

which layer is the middle layer of the eyeball

vascular tunic

what is a choroid. what layer is it a part of

vascularized, dark brown, lines inside of much of sclera, absorbs light to minimize scatter. vascular tunic

Describe tapetum lucidum in domestic animals

added layer of choroid, reflects light back towards the retina and causes animals eyes to glow

Describe the iris and what layer it is in

colored portion at the front of eyeball, with hole in the middle, aka the pupil. Vascular tunic

Describe pigment in the iris

many pigmented cells=brown

few= blue

describe the difference in a cat iris

cats have elliptical pupil, rather than round.

Describe location of the iris

lies between the cornea and lens, attached to ciliary processes of circular and radial smooth muscle that regulate the amount of light entering the eye

What is the inner layer of the eyeball

retina

What are the two layers of the retina

outer pigmented layer and inner neural layer

What are the three layers of the neural layer

1. photoreceptor layer

2. bipolar cell layer

3. ganglion cell layer

Describe the flow of retinas neural layers

light stimulates photoreceptors, signals to bipolar cells, ganglion cells and then optic nerve

Describe photoreceptors

• blind spot

• two types: rods work in dim light, cones have higher light threshold.

• rods outnumber cones 20:1 except in birds

Describe the lens

biconvex, transparent, avascular.

what changes shape to focus light to retina

lens

What is the lens held in place by

suspensory ligament attached to choroid

True or false. The lens contains epithelial cells on front surface and proteinaceous lens fibers

true

What are the two chambers of the eye

1. Anterior portion: between cornea and iris-aqueous humor

2. posterior portion: contains vitreous humor, may develop floaters

What is refraction

bending of light rays, inversion of image to upside down and backwards

describe accommodation in vision

change in shape of lens to focus image on retina, less able with age to adjust.

describe unique accommodation of birds and horses

Birds can keep object in focus regardless of distance. Horses move head to focus an object at different locations on the retina.

what is binocular vision

visible with both eyes

true or false humans have wider set to eyes

false, herbivores do

what controls the field of vision

location of eyes on the head

what within the ear controls sense of equilibrium

vestibular apparatus. Static and dynamic.

what are the three connective tissue membranes that overlay the CNS

Dura matter, arachnoid matter and pia matter.

Describe the role of cerebrospinal fluid (CSF)

maintain constant external environment for brain cells. Remove harmful metabolic products, protection, lymphatic system for brain.

where is CSF mainly produced

choroid plexus.

T or F. CSF provides movement of peptides produced in brain to site of action.

TRUE

What is the role of the BBB

isolates neurons from the systemic circulation

what forms the BBB

endothelial cells and astrocytes.

What does the BBB allow for

transfers of lipid-soluble molecules like carbon dioxide, oxygen, steroids, prostaglandins and alcohol. It also allows for carrier-mediated transport.

what does the BBB exclude

peptides and antibiotics

the meninges meanings

covering

describe dura mater

tough, fibrous layer over the brain

describe arachnoid mater

loose covering that doesn’t dip into sulci. sub-arachnoid space includes large blood vessels and CSF.

describe pia mater

inner layer with many small blood vessels

where is the spinal cord located

within the vertebral column. from foramen magnum at base of skull to about first or second lumbar vertebra

What surrounds the spinal cord

bone, meninges and CSF

What does the spinal cord contain

ascending and descending pathways to/from brain and nerve cell bodies coordinated motor activity.

describe central core of spinal cord

central core of gray matter with outer region of myelinated and unmyelinated nerve fibers