Nervous System Anatomy

Breakdown: Central Nervous System (CNS) Brain Spinal Cord Peripheral Nervous System (PNS) Somatic Nervous System Autonomic Nervous System – Sympathetic N.S. – Parasympathetic N.S.

Function of the CNS: Spinal Cord – Conducts sensory information to the brain – Conducts motor information to the brain Skeletal Muscle Cardiac Muscle Smooth Muscle Glands – Minor reflex center

Functions of the CNS: Brain – Receives sensory input from Spinal Cord and own nerves (e.g. olfactory/optical nerves) – Process information – Generates and coordinates appropriate responses

Functions of the PNS: Somatic Nervous System – Regulate body movement Control of skeletal muscle Reception of external stimuli (i.e. the senses!!) Summary: RECEIVE and REACT to the WORLD around us!!!

Functions of the PNS: Autonomic Nervous System Innervates: – Cardiac Muscle – Smooth Muscle – Glands Regulates hormone levels Homeostasis!!

Functions of the PNS: Sympathetic Nervous System Localized adjustments and reflex adjustments of cardiovascular system Whole system response: Fight or Flight Parasympathetic Nervous System Returns body to normal after Sympathetic response Vagus Nerve – originates in Medulla Oblongata, can play a role in controlling inflammation

The Brain

Major Divisions The brain of all vertebrates develops from three swellings at the anterior end of the neural tube of the embryo. From front to back these develop into the: – Forebrain (Prosencephalon) Cerebral Hemispheres: Telencephalon and Diencephalon – Midbrain (Mesencephalon) Substantia nigra, Ventral tegmental area (VTA) – Hindbrain (Rhombencephalon) Medulla oblongata, Pons, Cerebellum

Structures of the Hindbrain

Medulla Oblongata Rhythmic stimulation of intercostals and diaphragm Regulate heartbeat Regulate bloodflow (diameter of arterioles)

Pons Relays information from eyes, ears, and touch receptors from cortex to cerebellum

Cerebellum Functions: – Coordination of voluntary movement – Motor-learning – Balance – Reflex memory – Posture – Timing Contains as many neurons as rest of brain combined! Associated with Damage: – Loss of fine coordination – Tremor – Inability to walk – Dizziness (vertigo) – Slurred speech

Cerebellum

Midbrain Substantia Nigra: – Helps “smooth” out body motions Ventral Tegmental Area (VTA): – One of the pleasure centers of the brain (dopamine releasing neurons)

Brain Stem Midbrain Pons Medulla oblongata

Forebrain: Telencephalon Cerebrum – 4 lobes Frontal Parietal Occipital Temporal

Frontal Lobe Higher cognitive functions – Attention – Conscious thought – Voluntary movement – Decision making – Language – Planning – Problem-solving – Many more! Associated with damage: – Paralysis – Loss of spontaneity – Mood changes – Inability to express language – Atypical social skills and personality traits

Parietal Lobe Perception/Integration of somatosensory information (e.g. touch, pressure, temperature, pain) Visuospatial processing Spatial attention Spatial mapping Number representation Associated with Damage: – Inability to locate and recognize objects, events, and parts of the body – Difficulty in discriminating between sensory information – Disorientation – Lack of coordination

Parietal Lobe

Occipital Lobe Vision! Associated with Damage: – Hallucinations – Blindness – Inability to see color, motion, or orientation – synesthesia

Occipital Lobe

Temporal Lobe Recognition Perception (hearing, vision, smell) Understanding language Learning and Memory Associated with Damage: – Difficulty understanding speech, faces, objects – Inability to attend to sensory input – Persistent talking – Long and short-term memory loss – aggression

Temporal Lobe

Forebrain: Diencephalon Thalamus Hypothalamus Pituitary Gland

Hypothalamus – Hunger – Thirst – Body temperature – Arousal – Parenting – Perspiration – Blood pressure – Beart rrate – Shivering – Pupil dilation – Circadian rhythms Aggression Chronic stress Hypothermia Hypersomnia Lethargy Self-mutilitation Weight gain/loss

Hypothalamus

Thalamus Relaying motor/sensory information Memory Alertness Consciousness Contributes to perception and cognition Associated with Damage: – Amnesia – Apathy – Coma – Dementia – Difficulty speaking – Loss of alertness and activitaion – Sleepiness – Impaired processing of sensory information – Inattention – Impaired movements/posture – pain

Thalamus

Pituitary Gland Secretes hormones Referred to as the “master gland” Associated with Damage: – Loss of hormonal regulation in many areas of the body

Pituitary Gland

Crossing Over “Impulses reaching the spinal cord from the left side of the body eventually pass over to tracts running up to the right side of the brain and vice versa. In some cases this crossing over occurs as soon as the impulses enter the cord. In other cases, it does not take place until the tracts enter the brain itself.” How is this possible??? – Corpus Callosum!!

Corpus Callosum Connects right and left hemisphere and allows information to pass between them Associated cognitive disorders: – Coma or vegetative state – Schizophrenia – Psychotic episodes – Memory impairment – Split-brain syndrome

Corpus Callosum