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HUMAN REGULATION Nervous & Endocrine Systems REGULATION Integration of nervous & endocrine systems Similarities Secrete chemicals Major role in homeostasis Differences Nerve response – more rapid & shorter duration FUNCTIONAL DEFINITIONS Regulation: All the activities that help to maintain homeostasis in an organism Impulse: Message carried by the nerve cells Stimulus (stimuli) – Change in external or internal environment which initiates (starts) an impulse T YPES OF RECEPTORS FUNCTIONAL DEFINITIONS Receptors – Structures specialized to detect certain stimuli Effectors: Muscles and glands that respond to the stimulus Response: Change based on stimulus FUNCTIONAL ORGANIZATION OF THE NERVOUS SYSTEM Neurons Basic cellular unit Specialized for transmission impulse NEURON ACTUAL NEURONS IN BODY NEURONS THE NEURON Composed of: 1) Dendrites – fibers detect the stimulus & generate impulses toward the cyton 2) Cyton – cell body containing nucleus & most organelles THE NEURON 3) Axon – single long fiber that transmits impulse away from cyton to the terminal branches 4) Terminal branches – ends of axon – synaptic knobs secrete chemicals (neurotransmitters) THE NEURON 5) Synapse – space between adjacent neurons or between neuron & effector 6) Neurotransmitters – chemicals secreted to aid in transmission of impulse across synapse FUNCTIONAL ORGANIZATION OF NERVOUS SYSTEM Three types of neurons: 1) Sensory Neurons From receptors to central nervous system (brain & spinal cord) 2) Interneurons Inside CNS FUNCTIONAL ORGANIZATION OF NERVOUS SYSTEM 3) Motor Neurons Transmit from CNS to effectors (muscles and glands) FUNCTIONAL ORGANIZATION OF NERVOUS SYSTEM Nerves – bundles of neurons Can be sensory, motor, or mixed Specialized for impulse transmission over long distances CENTRAL NERVOUS SYSTEM 1) Brain Large mass of neurons Protected by skull Three major divisions: CENTRAL NERVOUS SYSTEM 1a) Cerebrum Largest part of brain Voluntary activity, memory, thinking, reasoning CENTRAL NERVOUS SYSTEM 1b) Cerebellum Coordination of motor activities Maintaining balance 1c) Medulla Involuntary activities – breathing, heartbeat, blood pressure, peristalsis Lowest part of brain Continuous with the spinal cord CENTRAL NERVOUS SYSTEM 2) Spinal Cord Lies within, & protected by, vertebrae of spinal column Coordinates activities between brain & other body structures Reflex actions PERIPHERAL NERVOUS SYSTEM 1) Outside CNS Nerves extending throughout body Two parts: Somatic NS – control voluntary muscles PERIPHERAL NERVOUS SYSTEM 2) Autonomic NS – two sets of nerves control involuntary muscles One set stimulates activity (sympathetic) Other slows down activity (parasympathetic) Central Nervous System Brain Spinal Cord Peripheral Nervous System Somatic Autonomic Sympathetic Parasympathetic NERVOUS SYSTEM MALFUNCTIONS Cerebral palsy – congenital diseases - motor function disturbance Meningitis – inflammation of membranes surrounding brain & spinal cord NERVOUS SYSTEM MALFUNCTIONS Stroke – cerebral hemorrhage (blood clot) in vessels - can result in brain damage Polio – viral disease of CNS; may result in paralysis; preventable through immunization TYPES OF BEHAVIOR Behavior – responses of living things to stimuli Reflex – inborn, involuntary response Involves a pathway (reflex arc) Impulse travels from receptor sensory neuron spinal cord (interneuron) motor neuron effector TYPES OF BEHAVIOR Habit – conditioned behavior acquired by repetition Repetition establishes pathways for nerve impulse transmission Permits automatic responses to various stimuli THE ENDOCRINE SYSTEM Made up of ductless glands located throughout the body & their hormones Hormones released directly into the bloodstream - affect various tissues or organs (target tissue) Hormones coordinate responses to various conditions HYPOTHALAMUS Small region of brain Produces hormones which influence pituitary gland PITUITARY GLAND Base of brain Secretes: 1) Growth Stimulating Hormone (GSH) Elongation of bones Affects metabolic activities for growth Problems with GSH Oversecretion in child: Giantism Oversecretion in adult: Acromegaly (enlarged bones of face, feet, hands) Undersecretion: Dwarfism 2) Thyroid Stimulating Hormone (TSH) Tells thyroid to produce thyroxin 3) Follicle Stimulating Hormone (FSH) Stimulates egg development in ovary & sperm development in testes THYROID GLAND In the neck Produces thyroxin, which contains iodine Thyroxin regulates metabolic rate – essential for proper development Problems with thyroid Oversecretion: nervous, weight loss Undersecretion: cretinism (mental retardation, small size) Deficiency of iodine – goiter (enlarged gland) PARATHYROID GLAND Embedded in thyroid gland Produces & secretes parathormone, which controls calcium metabolism Necessary for nerve function, blood clotting, proper growth of teeth & bones Problems with parathyroid Undersecretion: nerve disorders, brittle bones, clotting problems ADRENAL GLANDS Two – one on top of each kidney Each has two regions Outer portion – adrenal cortex Inner portion – adrenal medulla ADRENAL CORTEX Secretes two steroid hormones 1) Cortisone – regulates metabolism of organic molecules & promotes conversion of body fat & protein to glucose 2) Aldosterone – promotes reabsorption of sodium & chlorine ions by kidney into bloodstream – affects water balance & maintenance of blood pressure Problems with cortisone Oversecretion – Cushing’s disease (high glucose, excess fat) Undersecretion – Addison’s disease (low glucose, weight loss) ADRENAL MEDULLA Secretes adrenaline Increases blood sugar levels & accelerates heart & breathing rate ISLETS OF LANGERHANS Located in pancreas Secretes insulin & glucagon Insulin – allows glucose to enter cells from blood – lowers blood sugar levels Glucagon –stimulates release of sugar into blood – raises blood sugar levels Problems with pancreas Oversecretion of insulin – low blood sugar Undersecretion – diabetes (high blood sugar) GONADS Male – testes secrete testosterone – influences development of secondary sex characteristics Female – ovaries secrete several hormones, including estrogen – development of female secondary sex characteristics NEGATIVE FEEDBACK MECHANISM Type of self-regulation Level of one hormone in blood inhibits (slows) production of another hormone Keep everything in homeostasis TSH & thyroxin; insulin & glucagon Negative Feedback Mechanism POSITIVE FEEDBACK MECHANISM • Positive feedback – one promotes production of the other • Ex: snowball rolling down a hill