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Download Intro to the Human Body and Regulation
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THE HUMAN BODY Life Processes Regulation Nutrition Transport Respiration Locomotion Excretion Organ Systems Because humans are complex multicellular organisms, organ systems are needed to carry out the major life processes. Levels of organization: cellstissuesorganssystems Regulation The nervous and endocrine systems control and coordinate life activities to maintain homeostasis. This is known as regulation. Nervous System Nervous System Neurons – specialized cells that transmit electrochemical messages called impulses. This is how the body communicates rapidly producing responses of short duration. A Neuron Section 35-2 Neuron Nucleus Axon terminals Cell body Myelin sheath Nodes Axon Dendrites Neuron • Active transport maintains nerve cells in a charged state ready to transmit a message. • Nerve cells use lots of glucose and have lots of mitochondria. Active Transport Synapse Neurons communicate with each other by secreting chemicals across a tiny gap called the synapse. Figure 35-8 The Synapse Synapse Section 35-2 Direction of Impulse Dendrite of adjacent neuron Axon Vesicle Receptor Axon terminal Synaptic cleft Neurotransmitter Commonly Abused Drugs Section 35-5 Drugs Affect the Synapse Drug Type Medical Use Examples Effects on the body Stimulants Used to increase alertness, relieve fatigue Amphetamines Increase heart and respiratory rates; elevate blood pressure; dilate pupils; decrease appetite Depressants Used to relieve anxiety, irritability, tension Barbiturates Tranquilizers Slow down the actions of the central nervous system; small amounts cause calmness and relaxation; larger amounts cause slurred speech and impaired judgement Opiates Used to relieve pain Morphine Codeine Act as a depressant; cause drowsiness, restlessness, nausea Nervous System Central Nervous System Brain & spinal cord Peripheral Nervous System Nerve branches off the brain and spinal cord Sense organs Figure 35-9 The Brain Brain Section 35-3 Cerebrum Thalamus Pineal gland Hypothalamus Cerebellum Pituitary gland Pons Medulla oblongata Spinal cord Cross Section of the Spinal Cord Spinal Cord Section 35-3 Gray matter Spinal nerve Central canal White matter Meninges Sense Organs The Senses of Smell and Taste Section 35-4 Olfactory (smell) bulb Taste sensory area Olfactory nerve Thalamus Cerebral cortex Smell receptor Nasal cavity Smell sensory area Taste bud Taste pore Taste receptor Sensory nerve fibers Figure 35-14 The Eye Eye Section 35-4 Vitreous humor Muscle Lens Fovea Aqueous humor Cornea Pupil Optic nerve Iris Blood vessels Ligaments Retina Choroid Sclera Ear Figure 35-15 The Ear Section 35-4 Anvil Stirrup Hammer Oval window Semicircular canals Cochlear nerve Cochlea Bone Auditory canal Tympanum Round window Eustachian tube
