Homeostasis and Body Fluids 2024 PDF

‫سورة البقرة آية ‪32‬‬  Lecture Objectives By the end of this lecture you should be able to:- 1)Define homeostasis and mention its components. 2)What are the mechanisms needed to cool and warm our body. 3)What are the mechanisms needed to regulate water content. 4)What are the mec...

‫سورة البقرة آية ‪32‬‬  Lecture Objectives By the end of this lecture you should be able to:- 1)Define homeostasis and mention its components. 2)What are the mechanisms needed to cool and warm our body. 3)What are the mechanisms needed to regulate water content. 4)What are the mechanisms needed to regulate blood glucose level. 5)Give examples of positive feedback. 6)Describe composition of body fluids. 7)What is meant by water balance. Body Homeostasis HOMEOSTASIS  What is Homeostasis? ▪ The maintenance of a constant internal environment (in the body) is called Homeostasis  I- Homeostasis Conditions within the body must remain within a narrow range – like your body temperature a. Homeostasis involves keeping the internal environment within set ranges.  I- Homeostasis Components sensors gather data b. Control systems help maintain homeostasis. pore control center receives data, sweat glands sends messages communication hair system follicle muscle delivers messages to target organs, tissues targets respond to change goose bump  II. FEEDBACK LOOPS A. NEGATIVE FEEDBACK LOOPS ARE NECESSARY FOR HOMEOSTASIS Feedback compares current conditions to set ranges. Negative feedback stops the change.  Negative Feedback Loop Example: Holding breath, CO2 levels rise O2 / CO2 level returns to normal Control system forces exhale, inhale  Controlling body temperature ▪ All mammals maintain a constant body temperature. ▪ Human beings have a body temperature of about 37ºC. e.g. If your body is in a hot environment your body temperature is 37ºC If your body is in a cold environment your body temperature is still 37ºC  What mechanisms are there to cool the body down? 1. Sweating When your body is hot, sweat glands are stimulated to release sweat. The liquid sweat turns into a gas (it evaporates) 1ml H2O evaporates → loss of 0.6C (dry not humid climate). begins at skin T  34oC production of body  capacity of R, CD to get rid (explains sweating at 0oC in exercise or fever). Sweating The skin  What mechanisms are there to cool the body down? 2. VASODILATION ◼ Your blood carries most of the heat energy around your body. ◼ There are capillaries underneath your skin that can be filled with blood if you get too hot. ◼ This brings the blood closer to the surface of the skin so more heat can be lost. ◼ This is why you look red when you are hot!  This means more heat is lost from the surface of the skin If the temperature rises, the blood vessel dilates (gets bigger).  What mechanisms are there to cool the body down? 3. Mechanisms that decrease heat production: Anorexia. Apathy & inertia (decrease ms tone). ↓↓ Catecholamine, thyroxine  What mechanisms are there to warm the body up? 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 less heat can be lost.  This means less heat is lost from the surface of the skin If the temperature falls, the blood vessel constricts (gets shut off).  What mechanisms are there to warm the body up? 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 the body heat ◼ The air becomes an insulating layer.  What mechanisms are there to warm the body up? 3. Curling up 4. ↑ muscle tone and shivering. 5. Mechanisms that increase heat production: ❑ ↑ sensations of hunger & appetite. ❑ ↑ Catecholamine and thyroxine Effects of excess sweating Dehydration & loss of electrolytes (mainly Nacl) → miner’s cramps (hot + humidity). Ttt: salt tablets + H2O or i.v. isotonic saline.  II. Positive Feedback – Torn blood vessel stimulates release of clotting factors – Growth hormones stimulate cell division - Action Potential c. Positive feedback increases changeof baby - Delivery platelets blood vessel fibrin clot white blood cell red blood cell Body Fluids  COMPOSITION OF BODY FLUIDS CATIONS (mmol/l) Plasma Interstitial Intracellular Na 142 139 14 K 4.2 4.0 140 Ca 1.3 1.2 0 Mg 0.8 0.7 20 ANIONS (mmol/l) Cl 108 108 4.0 HCO3 24.0 28.3 10 Protein 1.2 0.2 4.0 HPO4 2.0 2.0 11  FLUID COMPARTMENTS EXTRA CELLUAR INTRA CELLULAR FLUID FLUID INTERSTITIAL TRANSCELLULAR PLASMA FLUID FLUID CSF Intra ocular Pleural Peritoneal Synovial Digestive Secretions  Total Body Water ECF ECF Blood Interstitial Interstitial ICF ICF ICF BLOOD  VOLUME OF BODY FLUIDS IN 70 kg MAN TOTAL VOLUME = 42 L INTRA CELLUAR FLUID 28 L(ROUGHLY 2/3 OF TBW) ISF 10 L (ROUGHLY ¾ EXTRA CELLULAR FLUID OF ECF) 14 L(ROUGHLY 1/3 OF TBW) PLASMA 4 L (ROUGHLY ¼ OF ECF) 1) Which of the following would be a negative feedback response by the body to hyperthermia? A. Shivering B. Sweating C. Vasoconstriction of blood vessels in the dermis D. An increase in metabolic rate. 2) How much fluid (% of bodyweight) is in the intracellular fluid 3) How much fluid (% of body weight) is in the interstitial fluid? 4) How much fluid (% of body weight) is in the blood plasma? 5) What specific molecule is present in the plasma but not the interstitial fluid? 6) Give the relative amounts of sodium & potassium inside and outside of the cell 1) Which of the following would be a negative feedback response by the body to hyperthermia? A. Shivering B. Sweating C. Vasoconstriction of blood vessels in the dermis D. An increase in metabolic rate. 2) How much fluid (% of bodyweight) is in the intracellular fluid? 40% 3) How much fluid (% of body weight) is in the interstitial fluid? 15% 4) How much fluid (% of body weight) is in the blood plasma? 5% 5) What specific molecule is present in the plasma but not the interstitial fluid? Protein 6) Give the relative amounts of sodium & potassium inside and outside of the cell. Sodium: lower inside, higher outside