Neurons & The Brain
Nervous System Functions Sensory – gather info from inside and outside the body Integrative – receive the info and decide what to do about it Motor – respond to the info
Cellular Structure Neurons – structural and functional unit of the nervous system Cell Body – nucleus and most organelles Dendrites – short, highly branched, bring info in Axon – long, send info away from cell body Axon terminal – releases neurotransmitter (chemical message to next cell)
Neuroglial cells (support cells) Schwann cells - around axons (PNS) Produce myelin – a lipoprotein that insulates axon to keep impulses in Nodes of Ranvier – narrow gaps between Schwann cells
Astrocytes – star-shaped, support cells in CNS Oligodendrocytes – form myelin in CNS
Microglial cells – CNS, support, phagocytize bacteria and cell debris Ependymal cells – covers and lines CNS
The Brain 4 Major regions Cerebrum Diencephalon Brain stem Cerebellum
Cerebrum Divided into 2 cerebral hemispheres (left and right) Makes up half of the brain’s mass The surface is made of ridges(gyri) and grooves (sulci)
Lobes of the Cerebrum 4 lobes, divided by fissures (deep grooves/sulci)
Specialized Regions Somatic sensory area – found at postcentral gyrus, receives impulses from the body’s sensory receptors Primary motor area – found at the precentral gyrus, sends impulses to skeletal muscles Broca’s area – involved in our ability to speak
Cerebral areas involved in special senses Gustatory area (taste) Visual area Auditory area Olfactory area
Interpretation areas of the cerebrum Speech/language region Language comprehension region General interpretation area
Gray matter – outer layer, composed of cell bodies Layers of the cerebrum Gray matter – outer layer, composed of cell bodies Cerebral cortex White matter – inner layer, composed of axons (myelin makes it white Cerebral medulla
Corpus Callosum Connects the two hemispheres of the cerebrum Integrates motor, sensory, and cognitive performances between the cerebral cortex on one side of the brain to the same region on the other side
Diencephalon Sits on top of the brain stem, enclosed by cerebrum Composed of 3 parts Thalamus Hypothalamus Epithalamus
The Ventricles Network of fluid filled cavities in the center of the brain Contain choroid plexus – produce cerebrospinal fluid (CSF)
Thalamus Receives info and relays to the proper portion of the cerebrum
Hypothalamus Under thalamus Regulates body temperature, water balance, and metabolism Connected to the pituitary gland master endocrine gland
Houses pineal gland and choroid plexus Epithalamus Houses pineal gland and choroid plexus Pineal gland produces melatonin – regulates sleep cycle (circadiam rhythms)
Brain Stem Attaches brain to spinal cord Composed of 3 parts Midbrain Pons Medulla Oblongata
Midbrain Tracts of nerve fibers Reflex centers for vision and hearing Two bulging fiber tracts – cerebral peduncles
Pons Bulging center portion of brain stem Mostly fiber tracts Regulates breathing
Medulla Oblongata Merges with spinal cord Controls heart rate, blood pressure, breathing, swallowing, vomiting
Cerebellum Regulates coordination, balance, posture, speech, and movement