Chapter 6 The Nervous System-Introduction and Central NS Essentials of Human Anatomy & Physiology Seventh Edition Elaine N. Marieb Chapter 6 The Nervous System-Introduction and Central NS Lecture Slides in PowerPoint by Jerry L. Cook Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Nervous System – By the numbers 100 billion – # of neurons in brain 1300 grams – mass of adult brain (2.85 lbs) 400 grams – mass of newborn brain 20% - portion of blood that goes to brain

Organization of the Nervous System Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Figure 7.2

Functions of the Nervous System 1. SENSORY INPUT Monitor changes (stimuli) occurring inside/outside body 1 2. INTEGRATION Process/interpret sensory input Decide if action is needed 2 3 3. MOTOR OUTPUT Response (activation of muscle or gland) to stimuli Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Figure 7.2

Central Nervous System (CNS) CNS develops from the embryonic neural tube, during first month of fetal development Neural tube becomes brain and spinal cord Opening of neural tube becomes ventricles, which are four chambers within the brain that are filled with cerebrospinal fluid.

Protection of the CNS Scalp and skin Skull and vertebral column Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Figure 7.16a

Protection of the CNS Scalp and skin Skull and vertebral column Cerebrospinal fluid Meninges: dura mater (tough, outer membrane) arachnoid mater (mesh, middle membrane) pia mater (soft, inner membrane; lines brain) Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Figure 7.16a

Protection of the CNS Scalp and skin Skull and vertebral column Cerebro-spinal fluid Meninges Blood-brain barrier Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Figure 7.16a

Blood Brain Barrier Low permeability of capillaries in the brain tissue that helps to keep out many potentially harmful substances. However, some substances can pass through, such as: Fats and fat soluble molecules Respiratory gases Alcohol Nicotine Anesthesia

Regions of the Brain 1. 3. 2. 4. (Cerebrum) Figure 7.12 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Figure 7.12

1. CEREBRUM Consists of two hemispheres (right and left) Each hemisphere has four lobes Surface has ridges (gyri), shallow grooves (sulci), and deeper grooves (fissures)

Cerebral Hemispheres (Cerebrum) Central Sulcus Parietal Lobe Frontal Lobe Occipital Lobe Temporal Lobe Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Figure 7.13a

Layers of the Cerebrum GRAY MATTER - Outer layer composed mostly of neuron cell bodies WHITE MATTER - Fiber tracts inside the gray matter Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Figure 7.13a

(consolidates short- and long-term memory; spatial navigation) Specialized Area of the Cerebrum (thought, intelligence, motivation, personality) (complex sensory memory patterns) Hippocampus (consolidates short- and long-term memory; spatial navigation) Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Figure 7.13c

Parts of the Brain – Brain Stem Corpus Callosum (connects hemispheres) Third Ventricle Thalamus (encloses 3rd ventricle) Pineal Body (in the epithalamus) Hypothalamus Optic Chiasma Corpora Quadrigemina Pituitary Gland Pons Fourth Ventricle Medulla Cerebellum Figure 7.15a Spinal Cord Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

2. CEREBELLUM Located at the base of the brain Two hemispheres with convoluted surfaces Provides involuntary coordination of body movements

3. DIENCEPHALON (on top of brain stem) Made of three parts Thalamus – relays sensory input Hypothalamus One of the last areas to develop Helps regulate body temperature and metabolism Part of limbic system (emotions) Epithalamus – houses pineal body Produces melatonin (controls day/night cycle)

4. BRAIN STEM Attaches to the spinal cord Composed of three parts: Midbrain - reflex center for vision and hearing Pons - controls breathing Medulla Oblongata - controls heart rate, blood pressure, breathing, swallowing, vomiting

SPINAL CORD Extends from the medulla oblongata to the T12 vertebrae Runs through the foramen magnum (large hole) in the skull Below T12 is called the cauda equine (a collection of spinal nerves that fan out) Protected by meninges Central canal filled with cerebrospinal fluid.

SPINAL CORD Cervical enlargement Meninges Thoracic enlargement (end of spinal cord) Cauda equina Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Figure 7.18

Spinal Cord Anatomy Central canal filled with cerebrospinal fluid Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Figure 7.19

Traumatic Brain Injuries Concussion Slight brain injury No permanent brain damage Contusion Brain tissue destruction occurs Brain tissue does not regenerate Cerebral edema Swelling due to the inflammatory response May compress and kill brain tissue

Cerebrovascular Accident (CVA) Commonly called a STROKE Blood to a region of the brain is blocked, cutting off O2 to the brain tissue Caused by a blood vessel that ruptures or is clogged with a clot Causes loss of some functions or death

Transient Ischemic Attack (TIA) “Mini-stroke” that does not cause permanent damage Can be a warning sign of a true stroke

Alzheimer’s Disease Progressive degenerative brain disease mostly seen in the elderly Abnormal protein deposits and twisted fibers cause structural changes in the brain Causes memory loss, irritability, confusion and ultimately, hallucinations and death