Practical Physiology 1 2025 PDF

Section 1 NERVE AND MUSCLE EXPERIMENTS prof.dr.heba shawky  NERVE AND MUSCLE EXPERIMENTS These experiments are done using the sciatic-gastrocnemius preparation. 1- Simple Muscle Twitch (SMT) Definition : Single contraction followed by single relaxation due to single stimulus. Th...

Section 1 NERVE AND MUSCLE EXPERIMENTS prof.dr.heba shawky  NERVE AND MUSCLE EXPERIMENTS These experiments are done using the sciatic-gastrocnemius preparation. 1- Simple Muscle Twitch (SMT) Definition : Single contraction followed by single relaxation due to single stimulus. The stimulus: Single maximal stimulus indirectly (nerve stimulation). Principle: If we stimulate the sciatic nerve by a single maximal stimulus, the gastrocnemius muscle will respond by a contraction followed by relaxation. This is called the simple muscle twitch (SMT) It is formed of 3 phases: 1- Latent period =0.01sec Events that occur during latent period - Propagation of action potential through nerve fiber. - Synaptic delay in neuromuscular junction. - Generation of action potential on sarcolemma - Physical and chemical changes happen in muscle (Actin and myosin sliding, viscosity of muscle). 2- Contraction phase = 0.04 sec 3- Relaxation phase = 0.05 sec Total time of SMT= 0.1 sec 2- Effect of Temperature on SMT Principle: Warming of nerve and muscle results in : 1- Decreased viscosity (decreased resistance to contraction) 2- Acceleration of biochemical reactions responsible for contraction (decreased duration) Cooling of nerve and muscle has the opposite effect 1- Increased viscosity (increased resistance to contraction) 2- Deceleration of biochemical reactions responsible for contraction (increased duration) 3- Effect of fatigue on SMT Steps: 1. Draw SMT. 2. Apply 10 stimuli without recording, then record the next contraction. 3. Repeat until the contraction of the muscle is obviously weak. 4. Remove the electrodes on either side of the nerve and apply the electrodes directly to the muscle (direct stimulation) and record the responses. Fatigue lead to: -Decrease amplitude of SMT. -Increase duration of SMT. Explain: It is due to depletion of vesicle of acetylcholine in neuromuscular junction  SECTION 2 Effect of Several Successive Stimuli Prof.dr.heba shawky 4- Effect of Several Successive Stimuli "Genesis of Tetanus" Steps: In this experiment, arrange the apparatus as in SMT Repeatedly stimulate the muscle at a slow frequency (2 / seconds) so that the muscle produces separate contractions as low frequency stimulation allows sufficient time to the muscle to relax after contraction. The first few contractions will show stair case phenomenon. Increase the frequency of stimulation gradually (5 / seconds) so as each stimulus falls at the beginning of relaxation produced by the preceding stimulus, clonus is obtained. Further increase in frequency of stimulation (10 / second) so that each stimulus falls during contraction phase produced by the preceding one results in continuous contraction of higher amplitude called tetanus. Comments: Mechanical contractions can fuse to form tetanus, while electrical response (action potentials) never fuses. Muscles in the body contract by tetanic contractions and not by SMT. The tetanic contractions result in high and maintained mechanical response which enables the muscle to do useful work. Staircase phenomenon: When skeletal muscle subjected to rapidly repeated maximal stimuli( as in separate contractions, clonus and tetanus ) following a period of rest (to avoid fatigue ). It lead to series of contractions, each is greater than the preceding one until a state of maximum contraction is reached, due to elevated level of Ca+2 in the cytoplasm. 5- The Effect of Temperature on Clonus and Tetanus Effect of warming on tetanus: Steps: Adjust the frequency of stimulation so that the muscle responds by tetanus. Fix this frequency and pour warm Ringer's solution on the preparation and stimulate the muscle. Tetanus + Temperature = Clonus  Effect of cooling on clonus: Steps: Adjust the frequency of stimulation, so that the muscle responds by clonus. Then pour ice-cold solution on the muscle and stimulate the muscle Clonus + Cooling = Tetanus  Section 3 Compound Action Potential (CAP) and Nerve Conduction Velocity (NCV) Prof.dr.heba shawky  Compound Action Potential (CAP) and Nerve Conduction Velocity (NCV) - They are used to assess the conduction of electrical impulses along peripheral nerves. -CAP’s represent the summed action potentials of the neurons that comprise a nerve trunk. A- It has multiple peaks because it has different types of nerve fibers with different speed of conductions. B- Doesn't obey all or non law. because the nerve trunk has many NFs vary in stimulus threshold, So when the strength of the stimulus increase ,more nerve and muscle fibers stimulated , compound AP occur and more force of contraction of the whole muscle will result [recruitment of motor units] Motor unit :a motor neuron and all the muscle fibers it innervates Conduction velocity is calculated m/s by the formula, Nerve conduction velocity (m/s) = distance (d) / latency (t). d = distance (m) from stimulating electrode to recording electrode Latency = time needed by the impulse to be conducted from the stimulating to recording electrode (second) Stimulation of the median nerve and recording CAP What is the effect of nerve diameter on conduction velocity, and why? Increased diameter is associated with decreased internal resistance of the nerve fiber, leads to increased conduction velocity. What is the effect of myelination on conduction velocity, and why? The action potentials are generated only at the nodes and becomes the stimulus for the generation of an action potential at the adjacent nodes. The positive charges jump from the activated node to activate the neighboring one. The propagation of the action potential from node to node is called saltatory conduction.  Section 4 BLOOD EXPERIMENTS Prof.dr.heba shawky Composition of blood: Plasma 55% Cellular elements 45% Red blood corpuscles (erythrocytes) RBCs. White blood cells (leucocytes). Platelets (thrombocytes). A. Red Blood Corpuscles (RBCs) ERYTHROCYTES Shape and Size of RBCs - RBCs are non-nucleated biconcave discs. RBCs Count - In adult male: 5.4 million/mm3 - In adult female: 4.8 million/mm3 - It is higher in new born infants, athletes and at high altitudes - It is decreased in old age.  RED BLOOD CORPUSCLES RBCS “ERYTHROCYTES” Biconcave disc Hemoglobin (Hb) - It is the red oxygen-carrying pigment of RBCs - Hb% is the number of grams of hemoglobin in 100 ml (dl) of blood. It is in adult male: 15-16 g/dl in adult female: 13-14 g/dl In newborns: 19 g/dl. Hematocrit value (PCV) RBC volume / Total blood volume % - Adult male 46±6 % - Adult female 42±6 % I-Blood Indices: 1- Mean corpuscular volume: It is the average volume of single red blood corpuscle. MCV= PCV X 10 / RBCs count (millions) Normal range= 80-95 µm3 2- Mean corpuscular Hemoglobin (MCH): It is the average amount of Hb in a single red blood corpuscle MCH= Hemoglobin concentration (gm/100 ml) / RBCs count (millions) x 10 Normal range= 25-32 pg 3- Mean corpuscular hemoglobin concentration: It is the concentration of hemoglobin in RBCs. MCHC = Hemoglobin (gm/100ml) / Hematocrite (%) x 100 Normal value is 32-38 gm/dl Anemia: Definition: It is a decrease in the oxygen carrying capacity of blood, which may be due to: 1. Decreased number of RBCs 2. Decreased hemoglobin content of blood. Symptoms of anemia -Dizziness -Headache -Problems with growth, for children and teens -Shortness of breath -Skin pale or yellow -Cold hands and feet -Tiredness -Tachycardia Classification and Causes of Anemia: Anemia can be classified according to the size of RBCs and their hemoglobin content into 3 types: I-Normocytic Normochromic Anemia: - In this type of anemia the size of RBCs is normal (Normocytic) and their hemoglobin content is normal (Normochromic), but their number is decreased. Causes: 1- Acute Blood Loss (= Hemorrhagic Anemia): In sudden and rapid blood loss (= hemorrhage) 2- Bone Marrow Depression (= Aplastic Anemia): Depression of the bone marrow will result in a decrease of all blood elements (RBCs, WBCs, and platelets). It may be due to: - Exposure to X-rays and atomic irradiation, - Malignancy - Drugs, e.g. chloramphenicol 3- Excessive Breakdown of RBCs (= Hemolytic Anemia): - Infections, - Chemical poisons - Incompatible blood transfusion - Snake venom II-Microcytic Hypochromic Anemia (= Iron Deficiency Anemia) - In this type of anemia the size of RBCs is smaller than normal (Microcytic) and their hemoglobin content is less than normal (hypochromic). It is caused by iron deficiency and its causes III-Macrocytic Hyperchromic Anemia (= Megaloblastic Anemia) - In this type of anemia the size of RBCs is larger than normal (macrocytic) and their hemoglobin content is more than normal (hyperchromic). It is caused by vitamin B12 or folic acid deficiency.  Section 5 Anemia Cases Prof.dr.heba shawky Anemia Cases  A young female is admitted to hospital. She complains that she feels weak and tires easily. The following results are obtained on analysis of blood samples: Hb content 10.2 gm/dl RBCs 3.5 million/mm3 PCV 31% 1-Use the above values to calculate ( write the equation ): A)MCV B)MCH C) MCHC 2-How would you classify this anemia? 3-Enumerate two causes producing this type of anemia Hb content 10.2 gm/dl RBCs 3.5 PCV 31% MCV= PCV X 10 / RBCs count(millions) 31x10/3.5=88 Normal range= 80-95 µm3 MCH= Hemoglobin concentration(gm/100ml) / RBCs count (millions) x10 10.2/3.5 x10=29 Normal range= 25-32 pg MCHC=Hemoglobin(gm/100ml) / Hematocrite (%) x100 10.2/31x100=32 Normal value is 32-38 gm/dl  Section 6 Determination of Blood Groups Prof.dr.heba shawky  II. Determination of Blood Groups Importance of test: Blood grouping and cross matching is an essential requirement before blood can be transfused into any individual. Principle: - The red cells contain a series of antigens (agglutinogens) on their surface, while the plasma contains antibodies (agglutinins). - To determine the blood group, the red cells are made to react with sera containing known agglutinins. - The slide is then examined to detect the presence or absence of agglutination and hemolysis of RBCs. Antigen-antibody systems: the ABO and Rh system. The ABO System; 1- The cell membrane of RBCs contains a variety of antigens, the most important are those of the ABO system. 2- The ABO system includes 2 types of antigens: (A) antigen and (B) antigen. 3- At the same time there are antibodies in the plasma called agglutinins against the A or B antigens. 4- According to the presence or absence of A and B antigens individuals are divided into 4 major groups: - When neither A or B antigens is present, the blood group is O. - When only type A antigen is present, the blood group is A. - When only type B antigen is present, the blood group is B. - When both A and B antigens are present, the blood group is AB. 5- Agglutinins are never present in person’s plasma together with the antigen of the same type.  Blood Group A B AB O Agglutinogen A B A+B Absent Agglutinin Anti-B Anti-A Absent Anti-A +Anti-B % of population 40% 10% 5% 45% Materials: 1- Sterile disposable lancet 2- Alcohol and cotton swabs 3- Anti-A , Anti-B and anti-D Sera 4- Clean glass slides 5- Glass marking pencil 6- Mixing sticks  Procedure: 1. Divide the slide by the marker to 2 parts A and B. 2. Sterile your finger with alcohol and leave to dry. 3. Prick your finger to obtain blood. Place 1 drop of blood on each part of the marked slide. 4. Add1drop of anti-A serum (blue) to the A-side, and 1 drop of anti-B serum (yellow) to the side B. 5. Mix the blood and serum in each compartment by tilting the slide gently to and fro for 1-2 minutes or by using a mixing stick (one for each side). 6. Observe the slide for any agglutination of red cells. Agglutination is usually visible by the naked eye as dark red clumps of different sizes. Blood Grouping: Results: 1. If agglutination occurs on side A only: you have the blood type A. 2. If it occurs on side B only: you have type B. 3. If a reaction occurs on both sides: you have type AB. 4. If no reaction occurs on both sides: you have type O. Agglutination is observed with Anti: …………………. Your blood group is: …………………………………. Rh Factor: 1- The Rh-factor is an agglutinogen, which was discovered in rhesus monkey. 2- It is present in the RBCs of 85% of white population (in addition to the ABO system). The individuals who have this antigen are called Rh-positive, while who do not have it are called Rh- negative. 3- Antibodies against Rh antigens are called anti-D antibodies. They are not normally present in the plasma of either Rh- positive or negative individuals. 4- The anti-D antibodies appear only in the plasma when Rh- negative individual receives Rh-positive blood. Rh factor: Procedure: 1. Place 2 drops of your blood with one drop of anti-D on a dry clean microscopic slide. 2. Mix the anti-serum and blood by racking the slide gently to and fro for 2-3 minutes. 3. If agglutination occurs, the blood is Rh positive. Result: Agglutination present or absent: ………………………. You are Rh: ……………………………………………  Section 7 Determination of Blood Groups By students Prof.dr.heba shawky  Section 8 Importance of Blood grouping & Rh factor Prof.dr.heba shawky Importance Rh factor: 1- Blood transfusion 2- Rh incompatibility (Erythroblastosis Foetalis) * When Rh+ve male marries an Rh -ve female = fetus will be Rh+ve * Only during delivery a large number of the Rh+ fetal RBCs enter the mother's circulation. * An anti-D agglutinins are formed (sensitized) * When sensitized mother becomes pregnant again with Rh+ child.  * The antibodies (IgG) [small enough] cross the placenta to the fetus. * Agglutination & hemolysis of fetal RBCs: - Usually born dead. - If alive: severely anemic and jaundiced due to ++ bilirubin which crosses blood brain barrier (BBB) [not well developed] → brain damage called kernicterus. Important notes on blood group: 1st baby may be affected if Rh- mother is already sensitized by Rh+ blood transfusion. ABO anti-bodies (IgM) [Large] cannot cross placenta. Rh- female should never receive Rh+ blood When an Rh- female delivers Rh+ fetus, anti-D antibodies are given to her immediately after delivery to neutralize the D antigen & prevent sensitization. Indications of blood transfusion: 1. To restore whole blood as in haemorrhage. 2. To restore one element e.g. RBCs, WBC, platelets, plasma proteins, clotting factors. 3. In erythroblastosis foetalis. Precautions of blood transfusion 1. Compatible by cross matching. 2. Rh- person is transfused with Rh- blood. 3. Free from blood born diseases. 4. Free from contamination. 5. Fresh & with high Hb%. 6. Must be stored at 4 °C for 21 days maximum. Complication of blood transfusion 1. Agglutination * Blockade of capillaries: -Backache & joint pain -Angina pain (if coronary arteries are occluded). 2. Hemolysis → liberation of: 1. Hemoglobin: - increase blood viscosity → heart failure - Jaundice - Renal failure: death - Hypoxia 2. Potassium: hyperkalemia → arrhythmia. 3. Toxic substances e.g. histamine → VD ,hypotension & shock 2- Physical: excessive transfusion → overloading → heart failure. 3- Infective: e.g. infective hepatitis, AIDS or malaria. 4- Mechanical: air embolism  Section 9 Hemostasis Prof.dr.heba shawky  Hemostasis Stoppage of bleeding from injured blood vessel I-Bleeding time Definition Time needed to stop bleeding without clot formation Assess 1st and 2nd step of haemostasis: Vascular spasm and platelet function Materials: 1. Lancets 2. Stop watch 3. Cotton swaps 4. Alcohol 5. Filter paper Normal bleeding time? Normal bleeding time = 1-3 minutes What causes prolonged bleeding time? Purpura: Purple-colored spots appear on the skin or mucous membranes, including the membranes on the inside of the mouth II-Coagulation time(clotting time) Definition -It is the time needed for clot formation. -It assess the 3rd step of hemostasis → fibrin clot formation by intrinsic pathways Materials: 1-Lancets 2-Stop watch 3-Cotton swaps 4-Alcohol 5-Non heparinized capillary tube Normal coagulation (clotting time): 3-9 minutes What causes prolonged coagulation time? Causes of prolonged coagulation time 1. Haemophilia a. Haemophilia A (deficiency of factor VIII) b. Haemophilia B (deficiency of factor IX) c. Haemophilia C (deficiency of factor XI). 2-Vit. K deficiency What are the causes of Vit. K deficiency ? 1-Newly born infant 2-Prolonged antibiotic therapy 3-Bile duct obstruction Thank you