The Brain Cerebral Hemispheres cerebrum Ridges gyri Grooves

The Brain

Cerebral Hemispheres (cerebrum) • Ridges - gyri • Grooves - sulci (shallow) fissure (deep) Longitudinal fissure -separates in two halves

4 Lobes of Cerebrum • 1. Parietal - somatic sense area *crossed pathways *pain, temperature, touch, taste (gustatory) • 2. Occipital - posterior *visual area

• 3. Temporal - lateral areas *hearing (auditory), smell (olfactory), and memory • 4. Frontal - primary motor area *Broca’s area (motor speech) *Language comprehension

Cerebral cortex • • Outermost layer of brain Consists of gray matter Precentral gyrus - motor Postcentral gyrus - sensory **Corpus Callosum- fiber tract connecting hemispheres ; white matter

Diencephalon • Thalamus - sends sensory information to the proper region • Hypothalamus - body temperature, water balance, metabolism, limbic system (emotionalvisceral : thirst, hunger, sex, pain, pleasure), regulates pituitary gland • Epithalamus - has pineal body & choroid plexus of third ventricle (makes CSF)

Cerebellum • Located inferior and posterior to the cerebrum • Controls – Timing of muscles – Balance & Equilibrium Ataxia - damage to cerebellum causing loss of balance & coordination

Brain Stem • Midbrain - vision & hearing reflex • Pons - fiber tracts & breathing • Medulla Oblongata - heart rate, blood pressure, breathing, swallowing, vomiting *Reticular Formation - length of brain stem motor control of visceral organs *RAS (Reticular Activating System) - consciousness damage causes coma

Brain Protection Meninges - 3 tissue layers • Dura mater - outermost, tough, doublelayered *attaches to skull • Arachnoid mater - middle layer, contains threadlike extensions • Pia mater - innermost, delicate *attaches to brain Subarachnoid space is filled with CSF Meningitis - - inflammation of meninges Encephalitis - - inflammation of brain tissue

Cerebrospinal Fluid (CSF) Watery cushion in & around brain and spinal cord Formed in choroid plexuses * Lumbar (spinal) tap * Hydrocephalus - “water on the brain” CSF builds up in brain ventricles drained by a shunt

Blood-Brain barrier • Least permeable capillaries in body • Keeps out unwanted substances • Can’t keep out fats, respiratory gases, or fat-soluable molecules (alcohol, nicotine, anesthetics)