Sheep Brain LabApril 2-6, 2012

Master Watermark Image: http://williamcalvin.com/BrainForAllSeasons/img/bonoboLH-humanLH-viaTWD.gif

The BrainThe Brain

• Objectives– Identify key structures on the and sheep brain.– Describe the key structures and function of the

human brain– State the function and location of the forebrain,

midbrain, and hindbrain– Identify the 4 lobes of the cerebrum

http://wiki.answers.com/Q/What_are_the_differences_between_a_sheep_brain_and_human_brain

Purpose

• The purpose of today’s lab is to familiarize with the structure of the brain that is being presented in lab.

Neural Anatomy Lecture 17Neural Anatomy Lecture 17

Cerebrum -The largest division of the brain. It is divided into two hemispheres, each of which is divided into four lobes.

CerebrumCerebrum

Cerebellum

http://williamcalvin.com/BrainForAllSeasons/img/bonoboLH-humanLH-viaTWD.gif

Cerebral Cortex

Cerebral Cortex

Cerebral Cortex - The outermost layer of gray matter making up the superficial aspect of the cerebrum.

http://www.bioon.com/book/biology/whole/image/1/1-6.tif.jpg

Nerve bodies

AxonsDendrites

CerebrumCerebrum

CerebellumCerebellum

Axons that have myelin sheaths (insulating covering which allows for faster impulse transmission)

Unmyleinated dendrites and cell bodies (nerve bodies)

•Gyri – Elevated ridges “winding” around the brain. •Sulci – Small grooves dividing the gyri

Basic Structure of a Nerve Cell (Neuron)Basic Structure of a Nerve Cell (Neuron)

Grey matter – closely packed neuron  cell bodies form the grey matter  of the brain.

White Matter - neuronal tissue containing mainly long, myelinated axons (insulation).

Main Differences of Sheep Brain and Human Brain:

– Temporal lobe of a sheep is proportionately much smaller, and does not extend forward, overlapping the frontal lobe as it does in a human brain. (Auditory Processing – rely less on sounds and more on smell)

– The brain stem of a sheep extends along the dorsal surface (straight back instead of straight down) because sheep walk on all fours.

– A sheep brain has an enlarged smooth area along the ventral aspect of the temporal lobe that is the primary olfactory center of the cerebrum. This indicates how much sheep rely on olfactory senses compared to humans.

– Additionally, sheep have proportionally larger olfactory bulbs

Gloves on, place brain on tray

Posterior or CaudalAnteri

or

Exterior contains Dura mater

Medial

student.ccbcmd.edu/c_anatomy/sheep_brain/sheep_brain.PPT

Dorsal View – Whole Brain

Cerebrum

Longitudinal Fissure

GyriSulciCerebellum

Medulla oblongataSpinal

cord

student.ccbcmd.edu/c_anatomy/sheep_brain/sheep_brain.PPT

Ventral View - Anterior

Pituitary gland

Olfactory bulb

Olfactory tract

Cerebrum

student.ccbcmd.edu/c_anatomy/sheep_brain/sheep_brain.PPT

Ventral View – Optic Nerve and Chiasma

Optic chiasma

Optic nerves

(dura mater intact)(dura mater intact)(dura mater (dura mater partially partially removed)removed)

Lobes of the Cerebrum:

Frontal Lobe

Parietal Lobe

Temporal Lobe

Occiptal Lobe

Midsagittal Section: Cerebrum and Cerebellum

Cerebellum

Occiptal Lobe

Parietal Lobe

Cerebrum

Frontal Lobe

Corpus Callosum

Medulla oblongata Pons

Midsagittal Section: Cerebrum and Cerebellum

CerebellumArbor vitae

Cerebrum

Corpus callosum

Occiptal lobe

Fornix

Parietal lobe

Frontal lobe

Fourth Ventricle

Thalamus and Hypothalamus

Circadian Rhythm• 24 hour cycle regulated by the suprachiasmatic

nucleus of the hypothalamus• Regulates• Sleep cycles• Feeding patterns• Hormone Release• Sex Drive

• “Thrown out of rhythm”• Jet Lag• Seasonal Affective Disorder• Obesity• Depression

Clean up your station prior to leaving lab.

• Throw brain material in the white garbage cans in the lab rooms.

• Clean off dissecting tray.

• Wipe down lab station with Clorox wipes before leaving lab.