A network of billions of nerve cells linked together in a highly organized fashion to form the rapid control center of the body
Parts of the nervous system
Brain
Peripheral nerves
Spinal cord
Functions of the nervous system
Integrating center for homeostasis, movement, and almost all other body functions
Sensation
Reaction: motor output
The mysterious source of those traits that we think of as setting humans apart from animals
Central nervous system (CNS)
The brain and spinal cord
Peripheral nervous system (PNS)
Connects everything to the brain and spinal cord
Central nervous system (CNS)
Acts as body's control center, coordinates body's activities
Relays messages
Processes information
Analyzes information
Brain and spinal cord
Protected by bone
Wrapped in 3 layers of connective tissue = meninges
Space between arachnoid mater and pia mater (subarachnoid space) is filled with cerebrospinal fluid (CSF)
Cerebrospinal fluid (CSF)
A clear, watery fluid that baths the CNS
Functions of the cerebrospinal fluid (CSF)
Protective function
Distribution of peptides, hormones, neuroendocrine factors, other nutrients and essential substances to cells of the body
Wash away waste products
Affect cardiovascular dynamics
Grey matter
Has a grey color in the living CNS and contributes to 40% of CNS
White matter
Made of axons and contributes 60% of CNS, the presence of myelin gives it a white color
Major parts of the brain
Pons
Pituitary gland
Hypothalamus
Cerebrum
Medulla oblongata
Spinal cord
Cerebellum
Pineal gland
Thalamus
Spinal cord
Segmented into cervical, thoracic, lumbar, sacral and coccygeal regions
Gives rise to 31 pairs of spinal nerves
Not uniform in diameter throughout length
Cranial nerves
Olfactory
Optic
Oculomotor
Trochlear
Trigeminal
Abducens
Facial
Vestibulococlear
Glossopharyngeal
Vagus
Accessory
Hypoglossal
Peripheral nervous system (PNS)
Made up of all the nerves that carry messages to and from the CNS, including 31 spinal nerves and 12 cranial nerves
Divisions of the peripheral nervous system
Sensory division
Motor division
Sensory division
Transmits impulses from sense organs to the CNS
Sensory receptors
Pain receptors
Thermoreceptors
Mechanoreceptors
Chemoreceptors
Photoreceptors
Sensory receptors
Concentrated in sense organs like eyes, ears, nose, mouth, skin
Nociceptors
Pain receptors, high concentration in skin, pleural & peritoneal membranes
Physiology of pain
1. Nociceptor activation
2. Stimulus transmission
3. Perception
Somatic nervous system
Voluntary, conducts impulses from the CNS to skeletal muscles
Autonomic nervous system
Involuntary, conducts impulses from the CNS to smooth muscle, cardiac muscle, and glands
Brain
Mass of 100 billion neurons located inside the skull, responsible for thinking, learning, memory and emotion
Brain
Interprets information from senses to monitor and regulate the body
Four Main Brain Regions
Cerebrum (2 hemispheres)
Diencephalon
Brainstem
Cerebellum
Cerebrum
Largest, most conspicuous portion of the brain, responsible for thought, voluntary movement, intelligence, language, memory, senses, self-awareness, communication, recognition
Cerebral Hemisphere
Divided into 3 regions: Superficial cortex of gray matter, Internal white matter, Basal nuclei - islands of gray matter found deep within the white matter
Basal Nuclei/Ganglia
Set of nuclei deep within the white matter, regulate voluntary movement, provide subconscious control of skeletal muscle tone and coordinate learned movement patterns and other somatic motor activities, coordinate many slow, stereotypic activities such as walking
Lobes of the Cerebrum
Frontal
Parietal
Temporal
Occipital
Insula
Cortical Motor Areas
Control voluntary motor functions
Sensory Areas
Found in the parietal, occipital, and temporal lobes, allow for conscious recognition of stimuli
Association Areas
Integration, allow for analysis of sensory input, include prefrontal cortex, language areas, general interpretation area, visceral association area
The most detailed map of the brain ever seen reveals over 100 new regions and could 'revolutionise medicine'
Diencephalon
Forms the central core of the forebrain, contains the thalamus, epithalamus, and hypothalamus
Thalamus
80% of the diencephalon, sensory relay station where sensory signals can be edited, sorted, and routed, also has profound input on motor and cognitive function
Epithalamus
Above the thalamus, contains the pineal gland which releases melatonin, and the habenula which is involved in food and water intake
Hypothalamus
Autonomic regulatory center, influences heart rate, blood pressure, respiratory rate, GI motility, pupillary diameter, involved in emotional response, regulation of body temperature, food intake, water balance, sleep/wake cycles, hormonal control
Limbic System
Series of cortical structures surrounding the limit between the cerebral hemispheres and the brainstem, responsible for emotional life and higher mental functions like learning and memory formation