The Central Nervous System (CNS)
Learning Goals Learn the vocabulary Form and function Relation to homeostasis Textbook pg 427- 434
Introduction Flowchart The Nervous System The Central Nervous System (CNS) The Peripheral Nervous System (PNS)
CNS Protection 1. Meninges: three layers of tissue (meninga = membrane)
2. Cerebrospinal fluid: circulates through the central canal of the spinal cord and the ventricles of the brain; cushions brain from impacts, gives it nourishment, protects it from toxins
3. Blood-brain barrier: selected substances enter the cerebrospinal fluid (O2, glucose, alcohol, caffeine, nicotine, anaesthetics…) Keeps out viruses, bacteria, toxins
The Spinal Cord Nerve bundles emerges from the brain through the foramen magnum Extends downward through a hole (foramen) within the vertebrae
butterfly-shaped core of Grey matter (dendrites, cell bodies) surrounded by White matter (axons) KNOW THIS DIAGRAM
Dorsal Root – afferent axons enter & make synapses with interneurons in the grey matter Interneurons connect the dorsal root & the ventral root to each other & the brain. interneurons send info to the brain & the brain send info back Ventral Root – efferent axons carry information from spinal cord to peripheral muscles, organs and glands.
The Brain Humans pride themselves over animals, however… We lack strength and agility, our hearing, vision, sense of smell are relatively unimpressive, we reproduce slowly… BUT…
What makes Homo sapiens unique is intellect and reasoning
Regions of Brain
Hindbrain Located at the rear of the skull Oldest portion of the brain Consists of: Medulla Oblongata –involuntary behaviors such as breathing (detects CO2 in blood), heart rate, digestion etc. Cerebellum –motor responses, balance, fine motor skills Pons – bridge between the cerebellum and the medulla
Midbrain Along with hindbrain, called the brain stem Relays information between the brain and the eyes and the ears. Visual attention is linked to midbrain
Forebrain Uppermost region of the brain Derived character in H. sapiens Highly folded = more complex Makes up most of the brain Forms the cerebrum most developed part of brain Sensory, motor activities
Cerebral Cortex Surface of cerebrum Higher mental functions such as thinking, planning. Divided into hemispheres (L and R) by corpus callosum. Has fissures that increase surface area Divided into lobes
Each Hemisphere can be broken down into 4 lobes: Function Frontal lobe - movement of voluntary muscles (e.g. walking and speech). intellectual activities, planning judgement - personality. Temporal Lobe - vision and hearing. memory interpretation of sensory information. Parietal Lobe - touch and temperature emotions interpreting speech. Occipital Lobe vision interprets visual information.
Hypothalamus Regulates basic homeostatic functions of the body Important part of endocrine system. Produces hormones and governs the release of hormones from the pituitary
Basal Nuclei (ganglia): Thalamus: sorts sensory info like switchboard Sleepiness, wakefullness Basal Nuclei (ganglia): controls and coordinates voluntary movements Damage and Parkinson’s Disease
Cerebellum Separate from brain stem Receives sensory input Integrates info for balance, movement
Corpus Callosum Experiments http://www.youtube.com/watch?v=zx53Zj7EKQE part 1 (5:45) http://www.youtube.com/watch?v=u9u6cQYcOHw part 2 (4:34)
Learning Goals Learn the vocabulary Form and function Relation to homeostasis