NMAT Biology Physiology

• exocrine (duct gland) secretes enzymes and transports through duct and targets organ near gland
• endocrine (ductless gland) secretes hormones and transports through bloodstream and targets organ distant from gland
• positive feedback means the end product speeds up the production
• negative feedback means the end product slows down the production
• blood clotting is also known as homeostasis, in which occurs when the endothelium of the blood vessels is exposed to the blood, activating tissue factors that hasten up blood clotting reaction
• when homeostasis occurs, the blood platelets are aggravated and eventually ruptures
• homeostasis includes three steps: vasoconstriction, formation of platelet plug, coagulation or blood clotting which reinforces the platelet plug with a fibrin mesh
• fibrin mesh is formed in release of thromboplastin that will convert prothrombin to thrombin with the help of calcium ions, thrombin then converts to fibrinogen to fibrin
• ossification or osteogenesis is the process of bone formation by osteoblasts
• intramembranous ossification is the process of bone development from fibrous membranes
• osteoblasts secrete extracellular matrix and deposit calcium which then hardens the bone
• endochondral ossification is the process of bone development from hyaline cartilage
• until adolescence, hyaline cartilage persists at the epiphyseal plate (growth plate) which is the region between the diaphysis and epiphysis that is responsible for the lengthwise growth of long bones
• bile is formed in the liver, where it is essential for digesting fats and is found in ost animals including mammals and reptiles
• the kidney functions to rid of the body of waste materials that are either ingested or produced by metabolism
• kidney controls volume and electrolyte composition of the body fluids
• nephron is the functional unit of the kidney which each of it has a glomerulus where large amounts of fluid are filtered from the blood and a long tubule where filtered fluid is converted to urine
• aldosterone is an important regulator of sodium absorption and secretion of potassium and hydrogen ions
• aldosterone is stimulated by potassium concentration and increase angiotensin II levels which occur when the body has decreased sodium and water retention, helping to increase extracellular fluid and restore blood pressure to normal
• angiotensin II is the body's most powerful sodium-retaining hormone, which increases during low blood pressure or low extracellular fluid volume by increasing sodium and water reabsorption
• antidiuretic hormone or vasopressin increases water permeability in the tubules to conserve water in case of dehydration and serves as a key role in controlling the degree of dilution or concentration of urine
• immunity refers to the ability of our immune system to defend against infection and disease
• there are two types of immunity and they are dependent on the function of the B and T cells
• first type of immunity is called humoral immunity from serum antibodies produced by plasma cells
• "humoral" refers to to the bodily fluids where these free-floating serums antibodies bind to antigens and assist with elimination
• second type of immunity is called cell mediated immunity which can be acquired through T cells from someone who is immune to the target disease or infection
• "cell mediated" refers to the fact that response is carried out by cytotoxic cells
• humoral and cell mediated immunity can be gained by someone who has not been exposed to a specific disease through administration of T cells from someone who has already been exposed
• B cells "mature in Bone marrow" secrete antibodies and proteins that bind to antigens on pathogens to help phagocytes destroy them. each cell produces only one type of antibody
• T cells "mature in Thymus gland" has three types: 1st one is Cytotoxic cells kill virus-infected cells by secreting proteins that penetrate and puncture cell membrane. It shut offs the replication of the pathogen
• T cells "mature in Thymus gland" has three types: 2nd one is Helper T cells which stimulate other components of the immune response by secreting signaling molecules that activate other cells
• T cells "mature in Thymus gland" has three types: 3rd one is Supressor T cells which turns off the immune response once the pathogen has been defeated