Lab Practical 2 Anatomy and Physiology

Lab Exam 1 Homeostasis: the maintenance of relatively stable internal physiological conditions under fluctuating environmental conditions Endocrine System: all of the glands of the body and the hormones produced by those glands o Glands controlled directly by stimulation from the nervous system as well as by chemical receptors in the blood and hormones produced by other glands o Coordinates and integrates (the function of all the different physiological systems) Regulates the functions of organs in the body (homeostasis) o Produce and secrete chemical messengers known as hormones Exert effects only on Target cells (possess receptor cells for the specific hormones on them) Tropic hormones: stimulate the secretion of other hormones Feedback Loops o The release of hormones into the blood is controlled by a stimulus from the environment it is in (the body) When stimulated, an endocrine gland secretes its hormones o Action: Increase or decrease of hormone secreted into the blood stream Blood carries the hormones to target cells Which then exerts a biological action o Negative feedback when response reduces the original stimulus o Positive feedback when response stimulus increases the original stimulus Metabolism: the range of all biochemical reactions occurring in the body that are necessary to maintain life o Anabolism: the building up of small molecules into larger molecules; stores energy o Catabolism: the breakdown of large molecules into smaller molecules; releases energy; heat released in this reaction is used to maintain body temp in homeothermic organisms Thyroxine: secreted by thyroid gland when stimulated by TSH (thyroid stimulating hormone) o Most important hormone for maintaining metabolism o Also known As T4 or tetraiodothyronine o Normal levels: 4.5-11.2 mcg/dL o Higher levels: hyperthyroidism o Lower levels: hypothyroidism o Thyrotoxicosis: the release of too much thyroxine in the bloodstream o Production controlled by: Pituitary gland: directly by releasing the TSH Hypothalamus: indirectly by secreting TRH (thyrotropin releasing hormone) to stimulate the pituitary gland to release TSH o If TSH levels get too high thyroid gland enlarges and a goiter is formed o Process: Hypothalamus secretes TRH when thyroxine levels are low Pituitary gland secretes TSH when stimulated by TRH The TSH increases thyroid gland size causing it to secrete thyroxine o Increased levels will increase metabolic rate o Decrease levels will decrease metabolic rate o Plays a role in the production and break down of Cholesterol in the body Cholesterol o Needed for 3 main purposes: Production of sex hormones o o o A building block for human tissues Assists in bile production in the liver Made in the liver or ingested through animal based foods Carried in the bloodstream in packages called lipoproteins through the blood vessels Two types of lipoproteins VVV Low-density lipoprotein (LDL): if levels are too high, the cholesterol can clog arteries and contribute to heart disease, heart attacks, and strokes High-density lipoprotein (HDL): helps remove LDL cholesterol from your body by carrying it back to the liver, where it is broken down and eliminated from the body. Helping to protect against stroke and heart attack. Protective levels of HDL 60 mg/dL or greater, under 40 mg/dL are a risk factor for heart disease Total cholesterol level (LDL + HDL): Ideal lower than 200 mg/dL. Between 200 and 239 mg/dL is borderline, and above 240 mg/dL is high Insulin o Enables body cells to absorb glucose from the blood stream Stored as glycogen o Produced by beta cells of pancreas o Released when blood glucose levels increase Glucagon (a catabolic hormone) o Stimulates the breakdown of glycogen into glucose which is then released into the blood stream to be used by body cells o Produced: by alpha cells in the pancreas o Released: when blood glucose levels decrease Normal Blood Glucose levels: between 85-95 mg/dL Decreased levels can indicate: o Hypothyroidism or hyperthyroidism o Insulin overdose o Liver disease Increased levels can indicate: o Diabetes mellitus o Physical stress o Cushing’s disease o Steroid use Diabetes mellitus o Glucose stays in blood stream and body cells are unable to use it o Type 1: when not enough insulin is produced by pancreas o Type 2: pancreas produces insulin by body fails to respond to it (body cells do not absorb the glucose) Cortisol o Important in the body’s response to stress o Increases blood pressure, blood sugar and reduces immune response o Secreted by adrenal cortex when stimulated by adrenocorticotropic hormone (ACTH) o Production controlled by: Pituitary gland: directly by releasing the ACTH Hypothalamus: indirectly by secreting CRH (corticotropin releasing hormone) to stimulate the pituitary gland to release ACTH o High levels will decrease production of ACTH and CRH o Process: Hypothalamus secretes CRH when the body is stressed Pituitary gland secretes ACTH when stimulated by CRH Adrenal cortex secretes cortisol when stimulated by ACTH Epinephrine (associated with the sympathetic ns) o Adrenaline o Secreted by the adrenal gland in response to strong emotions o Highly regulated hormone, but have maintenance levels in the blood stream to maintain cardiovascular homeostasis o Increases heart rate, increase blood pressure (via vasoconstriction and HR); diverts blood to tissues under stress; bronchodilator; breaks down glycogen along with glucagon; works on contraction/relaxation of smooth muscle Blood: specialized connective tissue o Formed elements: living blood cells o Plasma: non-living fluid matrix o Functions: Distribution O2 from lungs & nutrients from digestion to body cells Transport of metabolic waste from body cells to elimination sites Transport hormones from endocrine organs to their target organs Regulation Maintains body temp, normal pH body tissues, fluid volume in circulatory system Protection Preventing blood loss and infections Plasma o Makes up 55% of total composition of the whole blood o Composed of 90% water Dissolved solutes Formed elements of blood o Make up 45% of total composition of the whole blood o Formed in the red bone marrow o Erythrocytes (98% of the elements) Function: transport O2 and CO2 Most common formed element Formed through erythropoiesis Bioconcave shape; have no nucleus or other organelles Major factor contributing to blood viscosity Vitamin B12 important for the normal development Low B12: RBCs grow but do not divide during their development leading to large RBCs Production: Specialized cells in the kidney detect and react to low levels of oxygen. EPO (Erythropoietin) production is increased and released into the blood stream Where it reaches stem cells in the bone marrow Which increases the production of RBC to increase oxygen carrying capacity of the blood Mean corpuscular volume (MCV): average volume of erythrocytes in a specimen, elevated or decreased in accordance with average erythrocyte size (most useful) Mean corpuscular hemoglobin (MCH): the amount of hemoglobin in an average erythrocyte Mean corpuscular hemoglobin concentration (MCHC): measures the concentration of hemoglobin in an average erythrocyte o Leukocytes Spherical, nucleated cells General function: defense and immunity Able to leave the blood and enter other body tissues Total WBC count: number of leukocytes per unit of blood Differential WBC count: the percentages of the different types of leukocytes present in the blood 5 types Neutrophil (50-70% of leukocytes) o Multilobed nucleus o o Granulocyte During an acute infection, phagocytosis of bacteria and fungi followed by enzymatic destruction Lymphocyte (25-45% of leukocytes) o Agranulocytes o T-cell Round nucleus takes up most of the cytoplasm Attack viruses & tumor o B-cell Large bean-shaped nucleus When stimulated by bacteria or toxins, they differentiate into plasma cells. These cells then produce and secrete antigen specific antibodies Monocytes o 3-8% of the leukocytes o Largest leukocyte with a large U or kidney-shaped nucleus o Agranulocytes o Phagocytosis: differentiate into macrophages in tissues for phagocytosis o Eosinophil o 2-4% of the leukocytes o Bi-lobed nucleus and red granules o Granulocyte o Attack parasitic worms; play a complex role in allergy and asthma; lessens the severity of allergic reactions o o Basophil (0.5-1% of leukocytes) o Bi-lobed nucleus and blue cytoplasmic granules o Granulocyte o Releases histamine and other mediators of inflammation; contains heparin; increases allergic reactions Platelets (thrombocytes) 150,000-400,000 mm blood Not true cells (formed from the breakup of large cells) Seal small openings in blood vessels; instrumental in blood clotting Platelet count: number of platelets per unit of blood Mean platelet volume: measures the average volume size of platelets Hematocrit: the percentage of whole blood made up of erythrocytes o Calculation: divide the height of the erythrocytes by the total height of the blood in the tube and multiply by 100 Hemoglobin: a protein contained in RBC’s that makes them bind easily and reversibly to O2 o Each hemoglobin molecule can carry 4 molecules of O2 o When hemoglobin combines with O2 it becomes oxyhemoglobin o The oxygen carrying ability of blood it directly proportional to its hemoglobin concentration Rh factor transfusions o If an Rh- person received blood from an Rh+ person: No problem first time Body takes time to build up Rh antibodies o After antibodies are present, they will attach the Rh+ blood o An Rh+ person can receive Rh- blood as long as the donor hasn’t previously produced Rh antibodies Erythroblastosis fetalis: when antibodies cross the placenta blood barrier and attack the erythrocytes of the fetus o Rhogam given to mom after birth to prevent making antibodies Autorhythmic cardiac cells: sets each beat in motion by an electrical signal; initiate and distribute action potentials throughout the heart muscle SA node -> Internodal pathway -> AV Node -> AV Bundle -> Bundle Branches -> Purkinjie Fibers Sino-atrial node (SA node) o o Specialized cells on the wall of he right atrium Pacemaker because it can alter the heart rate by altering the number of action potentials conducing through the heart o SA node action potentials start both the atria contracting Internodal Pathway o Pathway that carries the action potentials from SA node to AV node continuing the complete contraction of the atria Atrioventricular node o Action potential is delayed here, giving the atria time to fully contract and the ventricles to fill with blood, before the impulse is sent to the ventricles Atrioventricular bundle (bundle of his) o In interventricular septum of heart o Only electrical connection between the atria and the ventricles Bundle Branches o Separates into right and left branches o Conducts action potentials through the interventricular septum Purkinjie fibers o Wind superiorly after they branch from the bundle branches o Sends action potentials throughout ventricles, causing them to contract from apex to base Electrocardiogram ECG o Interpretation of the electrical activity of the heart over a period of time o Electrodes attached to skin o Measures rate and regularity of heart beats o P-wave: electrical depolarization of atria (systole) o P-R segment: represents the action potential delayed at the AV node; atrial depolarization complete o QRS complex: depolarization of the ventricles (systole) o Q wave: Represents the action potential traveling to the bundle of His and through the bundle branches o R wave: Represents the action potential traveling to the purkinjie fibers and the contraction of the left ventricle o S wave: represents the action potential traveling to the purkinjie fibers and the contraction of the right ventricle o S-T segment: represents the completion of ventricular depolarization; blood is pushed away from heart o T wave: repolarization of ventricles (diastole) o Heart rate in BPM can be calculated by counting the number of QRS complexes in a given time period Chronotropic: Ion modifiers that affect heart rate (negative lower HR and positive increase HR) Inotropic: ion modifiers that affect the force of contraction (negative decrease force, positive increase force) Heart rate o Number of beats per minute o Avg. 75 BPM o Tachycardia: HR >100 bpm o Bradycardia: HR < 60 bpm Sympathetic NS: stimulation increases heart rate during activity or stress (fight or flight) by acting on pacemaker cells o Norepinephrine and epinephrine o Process: SNC cardiac nerves release the neurotransmitter norepinephrine and stimulate the adrenal gland to release epinephrine into the blood stream When epinephrine binds to receptors on the heart, it further increases heart rate and contraction force Parasympathetic NS: stimulation decreases heart rate (at rest and digestion) Via the vagus nerve by acting on pacemaker cells o Acetylcholine Stroke Volume: amount of blood pumped by each ventricle with each heartbeat o SV= EDV – ESV o EDV: end diastolic volume (amount of blood in each ventricle at the end of diastole) o ESV: end systolic volume (amount of blood in each ventricle at the end of systole o Factors affecting: stretch of cardiac muscle; sympathetic nervous system Cardiac output: amount of blood pumped out by each ventricle in one minute o Liters per minute o CO = HR * SV