1. Five body systems are in contact with the external environment, the integumentary, digestive, urinary, respiratory and reproductive systems

Transcription

1 ANATOMY & PHYSIOLOGY I ( AB) PAUL ANDERSON 2008 UNIT 2 Key Concepts: REVIEW OF BODY SYSTEMS A. OVERVIEW OF BODY SYSTEMS 1. Five body systems are in contact with the external environment, the integumentary, digestive, urinary, respiratory and reproductive systems 2. The integumentary system covers the body and provides a protective barrier between the internal and external environments. 3. The digestive system absorbs nutrients from the external environment (of the digestive tract lumen) and transfers them to the internal environment of the blood and lymph. 4. The respiratory system allows the transfer of oxygen and carbon dioxide between the external environment of the lung air sacs and the internal environment of the blood. 5. The urinary system transfers wastes and excess amounts of water and electrolytes from the internal environment of the blood to the external environment of the kidney tubules, where urine forms. 6. The cardiovascular system connects the integumentary, digestive, respiratory and urinary systems with the body cells so cells can receive nutrients and oxygen and get rid of wastes, via the blood. B. DIGESTIVE SYSTEM Components: Alimentary Canal and Accessory Organs 1. Replenishes the internal environment with nutrients and water from the external environment. 2. This involves the physical/chemical breakdown (digestion) of food and the absorption of nutrients. Complex molecules (Polymers) must be broken down (digested) into smaller molecules (Monomers) before Absorption into the blood. Digestion is the first stage of Metabolism. Chemical Digestion Absorption DIET---> POLYMERS > MONOMERS >BLOOD -----> LIVER 3. Metabolism (processing) and storage of food molecules which regulates the chemistry of the internal environment (e.g. liver and pancreas control the blood sugar level).

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4 Human Anatomy & Physiology 1 (805) Unit 2 Key Concepts Page 4 C. RESPIRATORY SYSTEM Components: Air Passageways and Lungs Through Breathing and Gas (Alveolar) Exchange supplies O2 to the internal environment and removes excess CO2 and H+, therefore controlling the O2/CO2 levels and ph of the internal environment. H 2 O + CO 2 H 2 CO 3 HCO H + D. URINARY (EXCRETORY) SYSTEM Components: = Kidneys, which produce urine, Urinary Bladder which stores urine and tubes (Ureters and Urethra) to convey urine to exterior) 1. Excretes urine to control the chemistry and volume of the internal environment, i.e. controls fluid, ph and electrolyte balance. Urine contains N - wastes (e.g. urea, NH3) and excess amounts of needed chemicals (e.g. water, electrolytes). 2. Stores and voids (eliminates) urine. RENAL VEIN RENAL ARTERY reabsorption filtration

5 Human Anatomy & Physiology 1 (805) Unit 2 Key Concepts Page 5 E. CARDIOVASCULAR SYSTEM Components: Heart, Blood Vessels and Blood Circulates Blood which 1. Transports chemicals (O 2, CO 2, nutrients, wastes, electrolytes, hormones) and heat within internal environment and between internal and external environments and so controls chemistry, volume and temperature of internal environment. 2. Defends body against infection (via white blood cells and antibodies in blood) and prevents fluid loss (via coagulation). F. LYMPHATIC SYSTEM (includes IMMUNE SYSTEM ) Components: Lymphatic Vessels, Lymph and Lymphoid Organs of the Immune System : Lymph Nodes ( Glands ), Spleen, Thymus, Tonsils, Appendix. 1. Organs of the Lymphatic System Proper drain Interstitial (Tissue) Fluid and so prevent Edema (excess IF) i.e. lymphatic system controls fluid balance of the internal environment. Lymph Flow: IF > LYMPH > BLOOD 2. The Organs of the body s Immune System contain cells (lymphocytes and macrophages) and antibodies, which eat bacteria and neutralise antigens and so help prevent infection. Macrophages in the spleen remove old red blood cells.

6 Human Anatomy & Physiology 1 (805) Unit 2 Key Concepts Page 6 G. INTEGUMENTARY SYSTEM Components: Skin plus Appendages (Hair, Nails) 1. Protective Barrier between internal and external environments. 2. Body Temperature Control (via sweat glands, thermoreceptors, fat and blood vessels). 3. Sensation. Skin has receptors for pain, temperature, pressure and touch. 4. Synthesis of Vitamin D (in sunlight). Vitamin D promotes Ca and P absorption from the diet. 5. Excretion (e.g. of NaCl in sweat). H. REPRODUCTIVE SYSTEM Components: Primary Organs: Gonads (Testes, Ovaries) Accessory Organs: Ducts, Glands Sexual Reproduction of the species 1. Produces and transports gametes (sperm, ova). 2. Provides appropriate environment for Fertilization and Development of Offspring. 3. Secretes Sex Hormones (estrogens, androgens) which control sexual maturation, menstrual cycle, growth (of muscles/bones) and sex drive. 4. Produces milk for nourishment of offspring.

7 Human Anatomy & Physiology 1 (805) Unit 2 Key Concepts Page 7 I. SKELETAL SYSTEM Components: Bones, Cartilages, Ligaments, Joints 1. Supports soft tissues. 2. Body shape. 3. Protection of vital organs (e.g. brain, heart lungs). 4. Allows for adaptive (i.e. homeostatic) movements - forms attachment sites for muscles - has moveable joints - forms levers with muscles 5. Produces blood cells (in bone marrow). 6. Stores minerals (Ca/P). J. MUSCULAR SYSTEM Components: Skeletal Muscles, (which pull on bones via tendons) Contraction (generation of a force which pulls on bones) and Relaxation for: 1. Powering adaptive movements, both voluntary and reflex ( behaviour ). 2. Support and shape. 3. Heat production (for body temperature control). 4. Posture ("anti-gravity" muscles). 5. Protection of abdominal organs (via abdominal flexors).

8 Human Anatomy & Physiology 1 (805) Unit 2 Key Concepts Page 8 K ENDOCRINE SYSTEM Components: Endocrine Glands (e.g. hypothalamus, pituitary, thyroid, parathyroids, pancreas, gonads, adrenal glands) The Endocrine System is the body s slow acting communication and control system. It slowly coordinates and controls bodily functions via hormones ("chemical messengers") secreted into the blood in response to Stimuli for Hormone Secretion Biochemical Changes (e.g. increased blood sugar level causes release of insulin from the pancreas) Nervous Stimuli (e.g. stretching of uterus causes release of oxytocin from the pituitary gland Trophic Hormone (e.g. TSH from anterior pituitary causes secretion of thyroxine from thyroid gland) Hormones may circulate for long periods and cause long lasting effects. Many endocrine glands are subject to control from the hypothalamus which controls the pituitary gland (the body s master endocrine gland): the pituitary, in turn, sends out trophic hormones which control secretions of the other endocrine glands, mainly the thyroid gland, gonads and adrenal cortex Basic Components of Endocrine Control

9 Human Anatomy & Physiology 1 (805) Unit 2 Key Concepts Page 9 L NERVOUS SYSTEM Components: Central Nervous System, CNS (Brain & Spinal Cord) Peripheral Nervous System, PNS (Peripheral Nerves, Sense Organs) 1. The Nervous System is the body s rapid communication and control system. 2. The basic function of the Nervous System is to make speedy adaptive responses to environmental changes so as to rapidly restore homeostasis. 3. To carry out this complex basic function the nervous system has the following more specific functions: Sensing Environmental Changes (external or internal stimuli). Rapid Internal Communication via nerve impulses in nerve fibers and synaptic neurotransmitters at synapses between nerve cells (neurons). Control of Effectors to produce adaptive (homeostatic) responses via chemicals released at the neuroeffector junction. Control of the Endocrine System. Species Memory of inborn adaptive responses (reflexes) e.g. suckling, smiling, crying, grasping, salivation, pupillary reflex etc. Learning of new adaptive responses via synaptic changes. Aquired Memory (storage of sensory input and of newly aquired adaptive responses). Internal Processing of information via thought - reasoning etc. ("Higher Associative Functions") Basic Design of The Nervous System The basic design of the nervous system is therefore that of a reflex arc which rapidly connects stimulus with response.

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11 Human Anatomy & Physiology 1 (805) Unit 2 Key Concepts Page 11 Divisions of the Nervous System (see following diagrams) 1. The NERVOUS SYSTEM consists of the CENTRAL NERVOUS SYSTEM (CNS) located within the skull and vertebral column and the PERIPHERAL NERVOUS SYSTEM (PNS) consisting of all the NERVES of the body and major SENSE ORGANS. 2. The CNS consists of the BRAIN located within the braincase or cranium and the SPINAL CORD located within the vertebral column. 3. The SPINAL CORD is a two way communication link between the brain and the body and also independently integrates SPINAL REFLEXES. 4. The BRAIN ultimately controls all other parts of the nervous system as well as most of the ENDOCRINE SYSTEM. The brain has many localised functions including speech, body rhythms, thought, sensation, synaptic changes of learning and memory. 5. The PNS consists anatomically of CRANIAL NERVES coming from the brain and SPINAL NERVES from the spinal cord. 6. NERVES are bundles of NERVE FIBERS which are processes of NERVE CELLS (NEURONS). A nerve cell or NEURON functions to receive information and rapidly communicate with other cells via nerve impulses and release of chemical transmitters. The NEURON consists of a CELL BODY containing the nucleus and NERVE FIBERS, cytoplasmic processes which may be AXONS or DENDRITES. DENDRITES and CELL BODY are the receptive areas of the neuron, receiving impulses from other neurons or receptors at SYNAPSES. The AXON is the conducting and secreting region of the neuron. 7. Functionally the PNS is divided into a SENSORY (or AFFERENT) DIVISION and a MOTOR (or EFFERENT) DIVISION. 8. The SENSORY (or AFFERENT) DIVISION receives information from the environment via RECEPTORS and transmits this information to the CNS. The SENSORY DIVISION consists of all the sensory nerve fibers in the body plus major sense organs. 9. The MOTOR or EFFERENT DIVISION transmits controlling impulses from the CNS to EFFECTORS and consists of all the motor nerve fibers in the body. 10. Those motor nerve fibers which supply SKELETAL MUSCLE belong to the SOMATIC BRANCH of the PNS (or SOMATIC NS). 11. The SOMATIC NERVOUS SYSTEM is also called the VOLUNTARY NS since it controls SKELETAL MUSCLE and therefore voluntary behaviour. However, the somatic nervous system is also responsible for SOMATIC REFLEXES. A REFLEX

12 Human Anatomy & Physiology 1 (805) Unit 2 Key Concepts Page 12 involves the following components: a STIMULUS (specific energy change in the environment) RECEPTOR (cell specialised to detect the stimulus) SENSORY NEURON (conducting towards the CNS) which synapses with an ASSOCIATION (INTER) NEURON (within the CNS), which in turn synapses with a MOTOR NEURON, conducting away from the CNS towards the EFFECTOR which causes the RESPONSE. 12. Those motor fibers which supply the HEART, SMOOTH MUSCLE or EXOCRINE GLANDS belong to the AUTONOMIC NERVOUS SYSTEM (or ANS). 13. The RESPONSES of the ANS are largely INVOLUNTARY and internal, so not usually visible (eg. digestive movements, heart beat). Most organs controlled by the ANS are visceral organs (or viscera ). 14. The SOMATIC NS and the ANS differ as follows: the SOMATIC NS maintains homeostasis by controlling responses of skeletal muscles, whereas the ANS maintains homeostasis by controlling visceral responses the somatic pathway involves a single excitatory neuron which passes uninterupted to the effector. the autonomic pathway involves two neurons which synapse outside the CNS in a ganglion. autonomic impulses may excite or inhibit effectors. COMPARISON OF COMMUNICATION IN NERVOUS & ENDOCRINE SYSTEMS ENDOCRINE NERVOUS METHOD Hormones in Blood Nerve Impulses in nerve fibers & Neurotransmitters at synapses. SPEED Slow: depends on speed of blood Rapid < 130 m/ sec. for impulses. flow DURATION Long Lasting: hormones may circulate for hours, days before being broken down and excreted in urine. Very Brief (0.001sec. for impulses): sustained responses of effectors depends on frequency of impulses. LOCALISATION Non Localised (diffuse action). Hormone carried to all tissues but only target tissue responds Highly Localised to one cell or group of cells (discrete action) but diverging neuronal patterns allow one brain cell to control many muscle cells.

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