Sheep Brain Dissection
School of the Future, Manhattan
Summer Research Program for Science Teachers
August 2009
Course: Living Environment (Biology)
Grade: 9th or 10th
Time: 2 Days (45 Minute Periods)
Aim:
What are the major structures of the brain?
What are the functions of the major structures of the brain?
What are the similarities and differences between human and sheep brains?
Materials:
For each group of 4 students
Day 1 (45 Minutes):
- -- Students prep desks for dissection (tape down newspaper and set up clean/dirty side – where actual dissection will occur), obtain dissection kit and pan, while teacher troubleshoots.
- -- Students obtain sheep brain and begin observing gross anatomy and become familiar with anatomical directions (dorsal, ventral, anterior, posterior).
- -- (With dura mater removed), students should draw a sketch of the brain and label each hemisphere, olfactory bulb, cerebellum, cerebrum, brain stem, and optic nerves, etc. using provided guide.
- -- Students return their group’s brain to its plastic bag, which the teacher collects and work on cleaning their dissection area.
- - -When all brains have been collected and students are seated, the class can debrief the experience.
o What was interesting about the brain?
o How is the sheep brain similar to our brain? How is it different?
- -- Teacher will then give a 5-10 minute mini lesson about the major sections of the brain and their functions
o Cerebrum
§ Corpus callosum - a bundle of white fibers that connects the two hemispheres of the brain, providing coordination between the two.
o Cerebellum
o Brain stem
o Medulla – Here the nerves cross over so the left hemisphere controls the right side of the body and vice versa. This area of the brain controls the vital functions like heartbeat and respiration (breathing).
o Optic chiasm
o Olfactory bulb
- -- Extension
o The pons is next to the medulla. It serves as a bridge between the medulla and the upper brainstem, and it relays messages between the cerebrum and the cerebellum.
o The pituitary gland, which produces important hormones, is a sac-like area between the pons and the optic chiasm.
Day 2 (45 Minute):
- -- Students prep desks again for dissection (tape down newspaper and set up clean/dirty side), obtain dissection kit and pan, while teacher troubleshoots.
- -- Students obtain sheep brain again and use scalpel to sever brain along the corpus callosum.
o One half will be used for locating and labeling the different lobes and important structures.
§ Ventricles contain cerebrospinal fluid
§ The occipital lobe receives and interprets visual sensory messages
§ The temporal lobe is involved in hearing and smell.
§ The frontal lobe also plays a part in smell, plus dealing with motor function
§ The parietal lobe handles all the sensory info except for vision, hearing, and smell.
§ The thalamus is a "relay station" for sensory information. It receives messages from the nerve axons and then transmits them to the appropriate parts of the brain.
§ The pineal gland produces important hormones.
o After observing and labeling the required structures, one half of the brain should be sliced longitudinally.
o The other half can be sliced as desired (in order to allow students to explore the brain on their own).
§ Students will observe their slices and compare how the makeup of the brain is different in different slices.
· Gray matter vs. white matter.
Extension - If a microscope is available, slice off a very thin section of the cerebrum and put it on a slide, covering it with a drop of water and a coverslip. Look at it under 100X and 400X magnification. Follow the same procedure with a section of the cerebellum, then compare and contrast the two.
- To clean up, students will return the pieces of the brain to the plastic bag and then work on cleaning their table.
- After the brains are disposed of and the students are seated, we will debrief again.
o Discuss students experiences
o Take questions
o Reinforce similarities between human and sheep brain
- Assessment
o Label sheep brain diagram
o Match brain region to its function
o Application questions – could answered orally, as a written summative assignment or expanded into a research project
§ Show images of different mammalian brains and ask students to
· 1. Label the different regions/lobes
· 2. Hypothesize about the animal’s capabilities based on the appearance of the brain
o Ex. Humans – large cerebral cortex à greater cognitive ability
o Ex. Mice – large olfactory bulb à actute sense of smell
§ Brain injuries/disorders
· Mark is injured in a car accident and suffers damage to his temporal lobe. What tasks might he have trouble with as he recovers? Why?
· What symptoms would you expect those infected with Creutzfeldt-Jakob to suffer? Why?
· How does Alzheimer’s disease affect the brain and daily life?
NYS Science Standards:
Homeostasis and dynamic equilibrium
National Science Standards:
Behavior of Organisms / Matter, Energy, and Organization in Living Systems