8 - BRAIN PARTS

• What structures protect the frog’s brain?

  Braincase and vertebral column
• Which portion of the braincase must be crushed to expose the brain?

  Dorsal portion
• Which tool is best for removing dorsal braincase fragments?

  Blunt forceps
• Why should scissors or scalpel not be used for removing braincase?

  They dull quickly and give poor results
• Which tools can be used for advanced removal of lateral braincase walls?

  Pliers or forceps
• Why must extreme care be taken near the medulla during dissection?

  Cranial nerves emerge here
• Into what solutions can the brain be placed after removal?

  Water, formalin, or alcohol
• What is the most anterior part of the frog brain?

  Olfactory lobes
• How are the olfactory lobes separated?

  By a shallow median furrow
• What lies on the ventral surface of the olfactory lobes?

  Olfactory tracts
• What is the function of the olfactory lobes and tracts?

  Sense of smell
• Which brain structures lie posterior to the olfactory lobes?

  Cerebral hemispheres
• How are the cerebral hemispheres separated?

  By a pronounced median furrow
• What are the functions of the cerebral hemispheres?

  Coordinate olfactory sensations; odor discrimination
• Why are frog cerebral hemispheres relatively small?

  Lack higher learning centers; only primitive functions
• Where is the diencephalon located?

  Between cerebral hemispheres and optic lobes
• What is its shape in dorsal view?

  Diamond-shaped depressed area
• What dorsal structure projects from the diencephalon?

  Pineal body
• What is the shape of the pineal body?

  Slender, club-shaped stalk
• What is the function of the pineal body in frogs?

  Endocrine organ
• What vascular network covers the anterior diencephalon?

  Anterior choroid plexus
• What is the function of the anterior choroid plexus?

  Exchange oxygen, nutrients, waste across blood-brain barrier
• Where is the pituitary gland located?

  On ventral brain surface (if removed)
• Into what three lobes is the pituitary divided?

  Anterior, intermediate, posterior lobes
• Which pituitary lobe is the largest?

  Anterior lobe
• What hormone from the anterior lobe regulates growth?

  Growth hormone
• What hormone from the anterior lobe controls metamorphosis?

  Thyroid-stimulating hormone
• What hormone from the anterior lobe controls seasonal mating cycles?

  Gonad-stimulating hormone
• What is the function of the intermediate lobe?

  Controls melanocytes (skin pigment cells)
• What functions does the posterior lobe regulate?

  Blood pressure, water balance, smooth muscle tension
• Which mammalian hormone does posterior pituitary resemble in function?

  Vasopressin
• The posterior lobe is part of what structure extending from the diencephalon?

  Infundibulum
• What is the shape of the optic lobes?

  Nearly spherical
• What do the optic lobes form part of?

  Midbrain (mesencephalon)
• Where are they located relative to the diencephalon?

  Posterior
• Where do optic fibers cross?

  Optic chiasma
• Where is the optic chiasma located?

  Anterior to pituitary gland
• What is the function of the optic lobes?

  Receive and interpret visual impressions
• What is the appearance of the cerebellum?

  Small transverse ridge
• Where is the cerebellum located relative to the optic lobes?

  Posterior