Physiology & Histology (ZOD104) - L1 & L2 PDF

Physiology & histology (zoD104) Contact Course Coordinadors : Prof. Dr. Eman Salah Abdel-Reheim WhatsApp: available Prof. Dr. Sanaa Reda  Lecture Regulation The general rules of classroom protocol: 1. Arrive on time. 2. Please avoid side conversations during explanat...

Physiology & histology (zoD104) Contact Course Coordinadors : Prof. Dr. Eman Salah Abdel-Reheim WhatsApp: available Prof. Dr. Sanaa Reda  Lecture Regulation The general rules of classroom protocol: 1. Arrive on time. 2. Please avoid side conversations during explanation. 3. Limit food to those that can be eaten quickly and quietly. 4. Please turn mobile phones to silent in the class.  The Course Goal: ‽ What do you want or expect to study in this part of the course? The course provide the medical graduate with the basic concepts of physiology. Homeostasis, body systems and their control.  Evaluation There will be 2 assignment per my course part for the midterm and oral degrees. All exams will have similar designs including multiple choice questions, matching, true or false, scientific expression, complete or short essay. Presence will be included in your evaluation. Protocol Signature  L1 Homeostasis By Pro. Dr. Eman Salah Abdel -Reheim Lecture outlines Definition of Homeostasis Its Mechanism & Regulators Body Systems role in Homeostasis Control Systems of Homeostasis Components of Homeostasis  Introduction Physiology study of function of living organisms, and the scientific methods applied to determine how organisms/ systems/ organs/cells biomolecules carry out the chemical /physical functions Body cells work best if they have the correct and constant media and requirements e.g. Osmoregulation Blood glucose O2 and CO2 concentration Body Temperature Blood pressure Blood pH Your Body Has Mechanisms to Keep the Cells in A Constant Environment.  Homeostasis and Life Homoio Similar Stasis Position ▪Homeostasis is the maintenance of a steady environment in the body despite the changes in the external environments ▪The steady state is the optimum condition for the body functions. Life is a dynamic process Cells of the body work like machines, consume fuels and produce waste Cells, the fundamental units of life, exchange nutrients and wastes with their surroundings: The intracellular fluid is “conditioned by”… the interstitial fluid, which is “conditioned by” the extracellular (plasma) “conditioned by” the organ systems it passes through. ICF ISF plasma organs external environment internal environment  Studying physiology is a study of how the body contributes to homeostasis. Threat to homeostasis The dynamic nature of life The opposite forces in our environment Our body is prepared to detect the challenges (threat) face the threat response and neutralize the challenge When the responses are inadequate in relation to the challenge, person falls ill The basis of health is the organism’s success in maintaining the internal balance and the body could be adjusted to meet serious external/internal danger. Hippocrates as long ago as 400 BC stated that The body possesses the means for its recovery from illness  Regulators of Homeostasis A system in homeostasis needs A. Sensors (Receptor) to detect= gather data →senses B1. Control Center (to face)= receives data, interprets information, sends messages out → brain B2. Communication System (to face)= delivers messages to target organs, tissues →PNS (e.g. motor neurons) C. Targets (Effector) = respond to change. →muscles (move), glands (release hormones) The control system must be able to: Receive signal from the receptor. It senses deviations from the normal. Integrate this information with other relevant information. Send a signal to the appropriate organ or gland to make the necessary adjustment (response). Generally, hypothalamus in the brain is the control center. A disruption of homeostasis can be harmful. Homeostasis can be disrupted for several reasons. 1. sensors fail (don’t detect changes) 2. injury (overpower homeostatic controls) 3. targets do not receive messages (nerve issues) 4. illness (viruses or bacteria) Disease is nothing but deviation from homeostasis Regulation of body functions by the major systems Digestive system – Digestion, Absorption of nutrients, excretion of wastes – Transfer of materials from external environment to internal environment Cardiovascular system – Transportation of O2, CO2, nutrients, waste products, hormones etc Respiratory System : – Supply O2 & elimination of CO2 – Acid base balance Urinary System – Elimination of waste products – Water & electrolytes balance – Acid base balance – Blood pressure regulation Skeletal system – Support & protection – Movement – Reservoir for calcium Muscular system – Most of the voluntary movements are by skeletal muscles – Digestion movements Integumentary system – Protection – Temperature regulation Immune System – Defense against foreign invaders – Defense against cancer (foreign cells) Nervous System – Control system of the body – Coordination of body activities – Quick response to stimuli – Consciousness, memory and intellectual functions Endocrine System – Another major control system – Control of metabolism – Control of nutrients supply, storage and utilization Reproductive system – Reproduction – continuation of life  Homeostasis Control Feedback Systems in Homeostasis Negative feed back control System reacts in such a way as to arrest the change or reverse it. Positive feed back control System reacts in such a way as to enhance or amplify the change in the same direction. Most feedback systems in the body are negative.  Negative Feedback – Increased Blood Pressure Baroreceptors in walls of blood vessels detect an increase in blood pressure (BP). Brain receives input and sends signals to the blood vessels and the heart. Blood vessels dilate. Heart rate (HR) decreases. BP decreases. Positive feedback – +ve control is in lower cases. – Input increases or accelerates the response. – Examples are: Labour Oxytocin →↑uterine contraction →↑Oxytocin Baby suckling Clotting Homeostasis is regulated by 3 different components in its pathway, these are: a) Osmoregulation; b) Thermoregulation; c) Chemoregulation.  Osmoregulation RBCs in different solution concentration Isotonic: RBCs will not be affected Hypotonic: RBCs will burst Hypertonic: RBCs will shrink  Controlling body temperature (Thermoregulation) ▪ All mammals maintain a constant body temperature. ▪ Human beings have a body temperature of about 37ºC either in a hot or in a cold environment. ▪ Cold blood animal don’t have this Physiological thermoregulation but they regulate their temperature behaviourally. Penguins huddling to keep warm Mechanisms to cool the body down during high temperature 1. Sweating When your body is hot, sweat glands are stimulated to release s weat. (Give reason= GR) The sweat (liquid) turns into a gas (evaporates) To do this, it needs heat. It gets that heat from your skin. As your skin loses heat, it cools down. 2. Vasodilation ♨ Your blood carries most of the heat energy around your b ody. ♨ There are capillaries underneath your skin that can be fi lled with blood if you get too hot. ♨ This brings the blood closer to the surface of the skin s o more heat can be lost. ♨ This is why you look red in hot weather(GR).  Mechanisms to warm the body during low temperature 1.Vasoconstriction This is the opposite of vasodilation The capillaries underneath your skin get constricted (shut off). This takes the blood away from the surface of the skin so decrease t he loss of heat (i.e. maintain body heat). 2.Piloerection This is when the hairs on your skin “stand up”. It is sometimes called “goose bumps” or “chicken skin”. The hairs trap a layer of air next to the skin which is then warmed by t he body heat. The air becomes an insulating layer. What are the systems Involved in thermoregulation?  L2 Water Balance By Prof. Dr. Eman Salah Abdel -Reheim  Total amount of fluid represent a high variable percent of the human body weight. Infants: 75% or more water (low body fat, low bone mass) Adult males: ~60% water. Adult females: ~55% water (higher fat content, less skeletal muscle mass). Water content declines to ~45% in old age.  Body fluid has been divided into two compartments Intracellular fluid (ICF) Extracellular fluid (ECF) Inside the cells  Outside the cells 65% of total body water  35% of total body water Extracellular fluid includes Intravascular: Approximately 20-23% of ECF Plasma and lymph Extravascular Interstitial fluid (IF) Present between the cells Approximately 70-79% of ECF Transcellular ≈ 0.6% of ECF, e.g. synovial fluid pleural aqueous humor pericardial cerebrospinal fluid peritoneal fluids 20 10  Cell membrane: ▪ Separates ICF from surrounding IF. ▪ It is a selectively permeable membrane. ▪ Ions enter or leave via specific membrane channels or by specific carriers  Blood vessel wall  Separate IF from plasma   Solvent: water is the universal solvent.  Solutes: nonelectrolytes and electrolytes ◦ Nonelectrolytes: most are organic  Do not dissociate in water: e.g., glucose, lipids, creatinine, and urea Organic substances Inorganic substances  Glucose ▪ Sodium  Amino acids ▪ Potassium ✓ Electrolytes have greater  Fatty acids ▪ Calcium  Hormones osmotic power than ▪ Magnesium  Enzymes ▪ Chloride nonelectrolytes ▪ Phophate ✓ Water moves according ▪ Sulphate to osmotic gradients  Water intake = water output = 2500 ml/day  Water intake: Preformed (beverages & food) and metabolic water  Water output: urine, insensible water loss (skin and lungs), perspiration, and feces 200 ml Feces Metabolism 10% 250 ml 12% Sweat 100 ml Foods 30% Insensible losses 750 ml 400 ml skin (transpiration) lungs 2500 ml 300 ml 28 % 1500 ml Urine 60% Beverages 60% 1500 ml Minimum daily sensible water loss of 400-500 ml in urine to excrete wastes Average intake/day Average output/day Thirst mechanism is the driving force for water intake The osmoreceptors are thirst center in the hypothalamic, that are stimulated by dehydration signs ◦ Dry mouth ◦ An increase of plasma osmolality by 2–3% ◦ A decrease in blood pressure indicated by baroreceptor Increase in plasma osmolarity & thirsty lead to ADH (antiduretic hormone)release. Drinking water inhibits the thirst center Inhibitory feedback signals include. ◦ Relief of dry mouth and activate the stomach and intestinal stretch receptors.  Influence of ADH Stimuli Osmolality Na+ concentration  Hypothalamic in plasma ▪ Water reabsorption in Plasma volume osmoreceptors trigger or Stimulates BP (10–15%) collecting ducts is inhibit ADH release Osmoreceptors Inhibits proportional to ADH in hypothalamus Negative feedback Baroreceptors release inhibits Stimulates  Other factors may in atrium and large vessels trigger ADH release via  ADH → dilute urine Stimulates Posterior pituitary ▪ large changes in blood Releases ADH and  volume of body volume or pressure, e.g., Antidiuretic fluids hormone (ADH) fever, sweating, Targets vomiting, or diarrhea; Collecting ducts of kidneys ▪  ADH → concentrated blood loss; and Effects Water reabsorption urine and  volume of traumatic burns Results in body fluids Osmolality Scant urine Plasma volume