Sheep Brain Dissection/Responses to stimuli

Frontal Lobe

Large lobe in cerebrum, front part of sheep brain

Executive functions

Parietal Lobe

Large part of upper middle brain, separated by frontal by central sulcus

Sensory

Occipital lobe

Portion of brain located posterior/in back

eye sensations

Temporal lobe

Bottom of brain directly above brainsteam/cerebellum

Cerebellum

Portion located posterior to cerebrum in sheep brain

Vermis

Central ridge of the cerebellum

Sulci

Grooves of the brain

Gyri

Ridges of the brain

Central sulcus

separates frontal and parietal lobes

Lateral sulcus

separates the frontal and temporal lobes

Brainstem parts

Midbrain - top part of brain stem

Pons - middle brain stem

Medulla - posterior part of brainstem

Corpus callosum

Connects 2 hemispheres of brain

Lateral Ventricle

Contain CSF (cerebrospinal fluid) it is a cavity

One in right hemisphere, one in left

May need to remove septum pellucidum to view

Third ventricle

Top of brain stem

Fourth ventricle

Between cerebellum and brainstem

Cerebral aqueduct

Connects 3rd and 4th ventricles

Arbor vitae

In cerebellum, looks like a tree like structure “tree of life”

Thalamus

In forebrain, part of sensory and motor systems

Hypothalamus

end part of brainstem?

Hippocampus

Grey matter - Outside of brain

White matter - within inside

Sensory neurons

Used to convert electrical signals sent to CNS

Motor neurons

integrated in brain and response is sent through them

Mechanoreceptors

Touch, pressure, motion, stretch on the skin

Chemoreceptors

Chemicals dissolved in bodily fluids

Electromagnetic receptors

responsive to light

Thermoreceptors

Detects heat

Detects hot and cold temp (cold and hot bucket)

Nociceptors

Detects physical pain (relay signals to and from other parts of body

Elbow in water to see if referred pain relays to fingertips

Homunculus brain

shows the amount of mechanoreceptors found on different parts of the body

more receptors = increased sensitivity

Hearing receptors

Cochlea has ciliated hair cells that are receptors for auditory signals

CN VIII (vestibulocochlear nerve) damage causes hearing loss

Weber & Rinne tests - tests lateralization (one side louder)

Otolithls

Present in both chambers to detect movement

Referred pain

Occurs when the pain signals are sent to parts of the body that are unharmed

Elbow in water to see if referred pain relays to fingertips

Odorants

Thousands of these, what scents are detected by

Chemoreception of olfaction (smell)

Tastant

chemical that stimulates sensory receptor cells

Five tastants: sweet, salty, sour, bitter, umami

Photoreception of vision

Ciliary muscles used to help focus

Rods and cones - Rods are low light, cone is RGB and bright levels

Myopia

People can not see far away without lasses/contacts

ipsilateral eye

eye being exposed during consensual reflex

contralateral eye

eye not being exposed to light in consensual reflex

Optic chiasm

axons of optic nerves converge here, enter opposite sides of brain

lateral geniculate nuclei

axons enter in here, travel to primary visual cortex in cerebellum for information and production of images

Ciliary muscles

these contract while suspensory ligaments relax during near vision

Afterimage test

Eyes become sensitized or fatigued from extended staring at image

Blindspot test

optic disc → lacks photoreceptors and blind spot forms where no light detected

Chemoreception of gustation

Taste test depicting different parts of your tongue’s ability to detect taste

Chemoreception of olfaction

Test smelling different unknowns to test olfactory receptors ability

Mechanoreception of equilibrium

2 chambers in inner ear - utricle and saccule (maintain balance)

otoliths - calcium carbonate particles covering hair cells signifying movements

Cupula - gelatinous substance which moves to detect motion

Hearing loss

Conductive - interference with sound in outer/middle ear

Sensorineural - damage of inner ear

Tactile distribution/localization

mechanoreception of tactile stimuli,

different regions of body have different sensitivites