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Chapters 13 & 14. The Central Nervous System: The Brain and Spinal Cord. BRAIN. The Brain. 100 billion neurons 1.6 kg in males/1.45 kg in females (size is not representative of intelligence, only overall average body size) Complexity dictates processing power.
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Chapters 13 & 14 The Central Nervous System: The Brain and Spinal Cord
The Brain • 100 billion neurons • 1.6 kg in males/1.45 kg in females(size is not representative of intelligence, only overall average body size) • Complexity dictates processing power
Major Subdivisions of the Brain • Cerebrum • Cerebellum • Diencephalon • thalamus • hypothalamus • Brain stem • midbrain • pons • medulla oblongata Fig. 14-2 No functional area of the brain works alone
1. Cerebrum ~ 80% of the brain’s mass; the thinking center 2 cerebral hemispheres contain 4 distinct lobes: • Frontal– motor cortex • Parietal – sensory cortex • Occipital – visual cortex • Temporal– auditory & olfactory cortex Fig. 14-8 Each hemisphere primarily controls the opposite side of the body
2. Cerebellum • Coordination of movement • Balance and posture
3. Diencephalon (INTERBRAIN) Thalamus - receives sensory inputs and determines which of these signals to forward to the cerebral cortex Hypothalamus - regulates the pituitary gland, body T, food intake, emotion, sleep-wake cycle and memory; controls autonomic functions (heart rate, respiration, blood pressure)
Limbic System • The “emotional” center, important for perception of pleasure and pain & functions in memory formation • Includes hypothalamus, hippocampus (long-term memory formation), amygdala (processing of emotions)
4. Brainstemlowest part of the brain where it connects to the spinal cord Midbrain– processing of visual & auditory data Pons – contains respiratory center Medulla oblongata – relays sensory info to thalamus & other parts of brainstem; controls cardiovascular, respiratory and digestive activities
Protection of the Brain Several different mechanisms: • Skull & scalp hair • Meninges (connective tissue membranes wrapping the CNS) • Cerebrospinal fluid (CSF) cushions and nourishes the brain • Blood-brain barrier - separation of the CNS from general circulation; composed of the least permeable capillaries; helps to maintain homeostasis in the brain
Spinal Cord • Connects the brain & PNS • Located within the vertebral column • From brain stem through foramen magnum to second lumbar vertebra (L2), ends as “horse tail”- cauda equina