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Nervous, Endocrine, Immune Systems Nervous System MAIN FUNCTIONS: 1. Transmits impulses to organs throughout the body. 2. Responsible for sensing and responding to stimuli in the environment. STRUCTURE: Consists of nerve cells called neurons. Neurons are specialized for transmitting electrical signals called nerve impulse. Nervous System Nerves and Muscles There are 3 Types of Neurons: 1. Sensory neuron – sends messages from the body to the brain 2. Interneuron – connect sensory and motor neurons at the spinal cord 3. Motor neuron – sends messages from the brain to the body (muscles) Nerves work together with muscles for movement. An impulse begins when one neuron is stimulated by another neuron or by the sense organs. The impulse travels down the sensory neuron to interneuron in the spinal cord & brain. The brain will then send an impulse through a motor neuron to the necessary muscle or organ, telling it to contract. Interneuron Sensory Neuron Muscle Fibers Motor Neuron Nervous System - Disorders DISORDER: Multiple Sclerosis is caused by destruction of large patches on the protective covering of the neuron. Small, hardened scars appear along the axon which interferes with the normal transmission of impulses. Normal nerve function is slowed, and symptoms such as double vision, muscular weakness, loss of memory, and paralysis result. Two Main Divisions of the Nervous System – CNS & PNS 1. Central Nervous System (CNS) Cerebrum Consists of the brain & spinal cord Part to label Cerebrum Voluntary or conscious activities of the body. Site of intelligence, learning, judgment. Cerebellum Coordinates and balances actions of the muscles brain Cerebellum Brainstem Spinal Cord Function Medulla Oblongata (brainstem) Regulates the flow of information between the brain & body. Regulation of blood pressure, heart rate, breathing and swallowing. Spinal cord Main communication link between the brain & the rest of the body. 31 pairs of spinal nerves originate here. Some reflexes are processed here. 2. Peripheral Nervous System (PNS): Consists of the sense organs (eyes, ears, skin, tongue, and nose), cranial nerves, and all other peripheral nerves extending out from the spinal cord to the body parts. Endocrine System MAIN FUNCTION: Affects/controls the actions of other glands and organs by the secretion of hormones HORMONES: Chemicals that cause a reaction in another part of the body. Glands and the Hormones they Release: ENDOCRINE GLAND HORMONE EXAMPLE FUNCTION DISORDERS Pituitary Gland Growth hormone (GH) Controls growth (usually stops being released by late teens Giantism – too much HGH Pituitary Dwarfism – too little or early twenties) Thyroid Gland Thyroxine Controls or regulates body’s metabolism Pancreas Insulin, glucagon Adrenal Gland Aldosterone, cortisol HGH Hyperthyroidism – too much thyroxin Hypothyroidism – too little thyroxin Controls blood glucose levels (levels of glucose) Diabetes mellitus – too little insulin Help prepare the body for stress Cushing Syndrome – too much cortisol Addison Disease – too little cortisol Pituitary Gland Thyroid Gland Pancreas Immune System MAIN FUNCTION: Protects the body from invading pathogens (infectious agents) recognizes and destroys invaders that have entered the body 1st line of Defense Skin and Secretions- keep pathogens out of the body Skin & Body secretions – • Mucus, saliva & tears contain an enzyme that break down the cell walls of bacteria • Oil and sweat are acidic and kill bacteria 2nd line of Defense Inflammatory Response fights local Inflammation – a nonspecific defense reaction to tissue damage caused by injury or infection Fever – elevated body temperature infections 3rd line of Defense SPECIFIC Response Fights systemic Infections -infections that entered the bloodstream Antigens – A substance that triggers an immune response Antibodies – Proteins that recognize and bind to antigens. White Blood Cells- There is different types that fight off infections in different ways. T - Cells- type of white blood cell that is responsible for recognizing new infections Antigen binding sites Antigen Antibody Immune Problems Allergies: inflammatory response caused by over-reaction of the immune system to antigens Asthma: severe allergic response which narrows airways Autoimmune Disease - the immune system mistakes its own body’s cells as foreign and attacks them. Two Examples: 1. Multiple Sclerosis – Myelin sheaths on nerve cells are attacked, slowing down nerve impulses. 2. Rheumatoid Arthritis - Joints are attacked causing them to become inflammed.