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HUMAN ORGAN SYSTEMS II REGULATION NERVE AND CHEMICAL CONTROL Nervous System Main organs: brain nerves neuron nerve cord Functions: To pick up stimulus from the body and the environment and respond appropriately. Maintain homeostasis by controlling and coordinating functions throughout the body. Neurons: the main functional unit of nervous system Cell body-largest part of the neuron Dendrites-carry impulses towards cell body Axons-long fibers that carry impulse away from cell body Synapse-small gap where impulses cross from one neuron to the next How an impulse travels along a neuron: the dendrite is the input site the axon is the output site neurotransmitters are chemicals that allow the impulse to move across a synapse. These are released by the axon types and picked up by the dendrites, like puzzle pieces. Axon=output signal or impulse Dendrite=input stimulus Electrical signal is caused by movement of sodium and potassium ions. Both are positive ions, but there are always more sodium ions outside of the cell than there is potassium ions inside. This makes the inside of the cell less positive or ‘negative’ than outside. When this is the case, the neuron is at ‘rest’. When Mario’s hammer hits Luigi’s foot an impulse is sent to the neuron, specifically the dendrite-the input site. The neuron will no longer be at the resting potential. It will have the potential to respond and this is called the action potential. The response comes as an electrical impulse along the Axon. The axon, through the use of protein channels and gates, will allow more sodium ions into the cell. This shifts the charge from negative to positive. This shift will continue all the way down the axon until it reaches the synapse. Interneuron Motor neuron During the resting potential, the protein gates allow three sodium ions out of the Cell while keeping only 2 potassium ions inside=more positive outside. The reverse Happens during the action potential-allowing more sodium in while letting fewer Potassium out. As the sodium and potassium ions change locations all the way down the axon, three things happen 1. the impulse travels closer and closer to the synapse. 2. the resting potential returns to the neuron once the impulse passes. 3. the action potential is transferred to the next neuron A synapse is a microscopic gap between one neuron and another neuron And where the impulse will be transferred to another neuron. The Impulse is transferred through the secretion of neurotransmitters. Neurotransmitters are amino acids that move Across the gap and fit into shape specific Receptors on the dendrites of the next neuron. This activates the next neuron and the impulse. Vesicle releasing neurotransmitters into synapse Vesicle containing neurotransmitters Receptor sites for neurotransmitters on next neuron Direction of impulse Central Nervous System: a. brain 100 billion neurons 1. cerebrum-largest left and right sides intelligence, learning, judgment 2. cerebellum-coordinates and controls muscle activity balance 3. brain stem-connects brain to spinal cord involuntary life dependent actions b. spinal cord connects brain to body 1. spinal nerves i. Reflex automatic reaction Peripheral Nervous System: a. nerves and cell that are found outside brain and spinal cord. 1. sensory-impulses from sensory organs to CNS ** sight, hearing, taste, touch, smell** 2. motor-impulses from CNS to muscles and/or glands 3. somatic – controls voluntary activities such as voluntary muscles 4. autonomic – involuntary activities Organ system: Skeletal Main organ: BONE=living cells + protein fibers + Ca a. cartilage b. spongy c. compact d. ligament e. marrow Function: support and movement protection production of blood cells store Strength – arches less dense Strength, more dense, storage of Ca, Mg, and P, blood vessels Connective tissue, produces red blood cells, stores fat, removes old blood cells Supplies Blood to Living cells Provides protection, nourishment and sensation Joints: where two bones meet. a. moveable – hinge pivot gliding (saddle) ball and socket b. immoveable – ribs skull : ligaments- hold bones together strong connective tissue : cartilage-connective tissue that cushions, supports, provides nutrients for bone growth Organ System: Muscular Main organ: Muscle smooth striated (skeletal) cardiac tendons Human body has more than 600 Muscles – over 400 are skeletal Function: Movement of bones Protection of organs Composition of organs Striated or Skeletal Muscle: Muscle that is attached to bone Muscle that can contract and relax Muscle that is made of bands of tissue Muscle that will tire over time Muscle is voluntary Contracted muscle: shortened pulls bone Relaxed muscle: longer Muscle fiber=muscle cell: some of the largest cells in the body Muscle cells contain many nuclei. Remember: action of muscles will require ATP for energy Muscle fibers slide over each other CONTRACT – shorten and pull bone Muscle fiber return to RELAXED position Muscles work in pairs: when one relaxes the other contracts. Contracted muscle pulls lower arm up Tendon-bone to muscle Relaxed muscle Relaxed muscle Relaxed muscle: forearm is down Contracted muscle: forearm is pulled up Smooth muscle: Muscle that composes major organs Muscle that can contract and relax Muscle that is composed of continuous sections of cells-look smooth Muscle that does not tire over time Muscle cell contains only one nucleus Muscle is involuntary Cardiac Muscle: Muscle that is found in the heart Muscle that can contract and relax Muscle that looks like striated but functions like smooth Muscle that does not tire over time Single nucleus Muscle is involuntary 0RGAN SYSTEM: INTEGUMENTARY MAIN ORGAN: SKIN EPIDERMIS DERMIS NERVES MELANOCYTES HAIR FOLLICLES SWEAT GLANDS THICKNESS OF SKIN WILL RANGE BETWEEN .55MM (EYELIDS) TO 4MM (SOLES OF FEET/PALMS OF HANDS .1 INCH 1 INCH THERE IS APPROXIMATELY 22 square feet of skin on the average adult human FUNCTION: PROTECTION-BARRIER HOMEOSTASIS – TEMPERATURE RESPONSE TO ENVIRONMENT EXCRETORY ENDOCRINE SYSTEM: system of glands that produce and secrete hormones that connect nervous system to brain Hormones activate the production Of enzymes w/in the nucleus Functional units glands hormones-steroid nonsteroid target cells Exocrine glands secrete through ducts Endocrine glands secrete into bloodstream Glands of the endocrine system Hypothalamus-found within the brain-cerebral cortex controls pituitary gland Pituitary – controls most of the endocrine glands produces large number of different hormones Thyroid – controls metabolism Parathyroid – controls levels and absorption of calcium Adrenal gland – regulate water balance, and as a result BP increases metabolism, heart rate, breathing helps to convert complex fat and protein into simpler glucose molecules Islets of Langerhans – produce insulin and glucagon=storage nonsteroid of sugar Gonads – testes=testosterone ovaries=estrogen and progesterone steroid How do endocrine glands work? Negative feed back Example: Mary Lou eats 5 donuts for breakfast. Her stomach and small intestine breakdown the sugars in those donuts and the bloodstream absorbs the smaller molecules, raising blood sugar levels. The pancreas monitors blood sugar levels and if Mary Lou’s levels exceed 140mg/dl, the Islets of Langerhans will produce and secrete insulin. The insulin will gather all the excess glucose from the bloodstream and send it to the liver for storage. Four hours later, Mary Lou feels tired. The pancreas monitors lower levels of glucose and stimulates the Islets of Langerhans to produce and secrete glucagon that will stimulate the liver to release glucose. Example #2: from the text The levels of calcium are controlled by the parathyroid glands thyroid gland, kidneys, and the small intestine. If calcium levels are too high, the thyroid and parathyroid glands will produce and secrete hormones that will trigger the kidneys to absorb more calcium in the filtrate to be excreted with the urine. This hormone will also stimulate the bones to absorb and store more calcium If calcium levels are too low, the parathyroid will secrete PTH that will trigger the intestine to absorb more calcium, the kidneys to allow reabsorption of calcium from the neuron and the bones to release some of the calcium stored in them. Example #3: from last year Walking alone down a dark street www.abpischools.org.uk/page/modules/hormones Reproduction: Female Male Fertilization: Sperm + egg = zygote 23 + 23 = Diploid number returns 46