The Immune System PDF

The Immune System Chapter 52  The Lymphatic System Significant amount of water and solutes in the blood plasma filter through the walls of the capillaries to form the interstitial (tissue) fluid Most fluid leaves at the arteriole end of the capillary and returns at the venule e...

The Immune System Chapter 52  The Lymphatic System Significant amount of water and solutes in the blood plasma filter through the walls of the capillaries to form the interstitial (tissue) fluid Most fluid leaves at the arteriole end of the capillary and returns at the venule end Fluid that does not return to capillaries is returned to circulation by the lymphatic system 2 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Arteriole Lymphatic Capillary bed Venule Interstitial capillary fluid a. Lymphatic capillary Excess interstitial fluid becomes lymph Interstitial fluid Blood flow Capillary Filtration Absorption Arteriole Venule Blood pressure Osmotic pressure Pressure Net absorption due to osmotic pressure Net filtration due to blood pressure Arteriole Venule Direction of blood flow 3 b.  The Lymphatic System Consists of lymphatic capillaries, lymphatic vessels, lymph nodes, and lymphatic organs (spleen and thymus) Excess fluid in the tissues drains into blind- ended lymph capillaries Lymph passes into progressively larger vessels with one-way valves Eventually drains into subclavian veins 4 Overview of immunity  Immune System Body’s defenses are integrated Innate – Recognition of invading pathogens – Rapid response – Uses soluble antimicrobial proteins Adaptive immunity – Characterized by genetic rearrangements that generate a diverse set of molecules to recognize any invader – Slower response but highly specific 6  Innate immunity Skin – Largest organ of the body – Provides a nearly impenetrable barrier – Reinforced with chemical weapons – Oil and sweat glands give skin a pH of 3–5 – Lysozyme breaks bacterial cell walls – Also contains many normal flora Nonpathogenic microorganisms that out-compete pathogenic ones In microbiology, collective bacteria and other microorganisms in a host are 7 historically known as flora.  Innate immunity 3 other potential routes of infection – Digestive, respiratory, and urogenital tracts All 3 lined by epithelial cells – Cells secrete mucus which traps microbes Digestive tract – Salivary lysozyme; acidic stomach – Nonpathogenic normal flora Respiratory tract – Ciliary action Urogenital tract (sex organ) – Acidic urine, normal flora 8  Innate immunity Binding of a pathogen-associated molecule to any of the innate immune-type receptors activates signal transduction pathways that lead to a rapid response Nonspecific defensive molecules – Defensins = protein against bact, fungi, virus – Cathelicidin = mammalian innate immune against bacteria – Interferon= signaling protein against pathogens Inflammatory response 9  Innate immunity 3 kinds of defending leukocytes Macrophages – Kill microorganisms through phagocytosis – Monocytes mature into macrophages Neutrophils – Most abundant circulating leukocyte – Also use phagocytosis Natural killer cells – Do not attack invading cells directly – Induce apoptosis (programmed cell death) in target cell 10 11  Innate immunity Inflammatory response – Inflammation involves several body systems – Injured cells release chemical alarms, including histamine and prostaglandins – Cause nearby blood vessels to dilate and increase in permeability – Promote phagocyte accumulation – Hallmark signs – redness, warmth, swelling (edema), pain, and potential loss of function 12  The Inflammatory Response Redness, warmth, swelling (edema), pain  Innate immunity Inflammation is accompanied by an acute phase response – One manifestation is fever – Macrophages release interleukin-1 protein – Causes hypothalamus to raise body temperature – Promotes activity of phagocytes, while impeding microbial growth – However, very high fevers are hazardous as they may denature critical enzymes 14  Adaptive immunity The scientific study of immunity began with Edward Jenner in 1796 Observed that milkmaids who had cowpox rarely experienced smallpox (ฝี ดาษ) Inoculated individuals with fluid from cowpox vesicles to protect them from smallpox Vaccination 15  Adaptive immunity An antigen is a molecule that provokes a specific immune response It may be components of microorganisms or proteins/glycoproteins found on surface of red blood cells or transplanted tissue cells Each can stimulate a distinct immune response 16  Adaptive immunity Characterized by 1. Specificity of recognition of antigen 2. Wide diversity of antigens can be specifically recognized 3. Memory, whereby the immune system responds more quickly to an antigen it encountered previously than one it is meeting for the first time 4. Ability to distinguish self-antigens from nonself 17  Adaptive immunity B lymphocytes or B cells – Produced & continue development in bone marrow – Respond to antigens by secreting antibodies – Participate in humoral immunity T lymphocytes or T cells – Develop in thymus – Regulate other immune cells or directly attack cells that carry specific antigens – Participate in cell-mediated immunity 18  Humoral immunity Begins when naive B cells in secondary lymph organs meet antigens B cells are activated when their surface immunoglobulins (Igs) bind to a specific part on an antigen Activation results in clonal expansion and differentiation into plasma and memory cells Plasma cells produce soluble antibodies against the same epitope 19 20  Immune Responses The first encounter with a foreign antigen is called the primary immune response – Only few B or T cells can recognize antigen and mount response – Clonal expansion occurs – memory cells Second encounter is called the secondary immune response – This time there is a large clone of memory cells that can recognize the antigen – Immune response is faster and more effective 21 22 SEXUAL REPRODUCTION 23 Facts about the reproductive systems… Size of sex cells: – Female ovum = 1/175th inch – Male sperm = 500 lined up tail to tail would equal one inch  Production of sex cells Females are born with 200,000 – 400,000 immature ova. Approximately 375 will be released in a lifetime! One spoonful of semen can contain 100 million – 300 million sperm! Sperm Head- contains DNA The tip of the head is the acrosome, which enables the sperm to penetrate the egg. Midpiece- contains mitochondria which supplies the energy the tail needs to move. Tail- moves with whip- like movements back and forth to propel the sperm towards the egg. Testes Reproductive glands; produce sperm and testosterone Scrotum Sac-like pouch; holds testes and helps regulate temperature Epididymis Comma-shaped structure with a duct system; where sperm mature Vas Deferens Two long, thin tubes; provide passage and storage for sperm Seminal Vesicles Two sac like structures that produce fluids to help keep sperm alive Prostate Gland Produces some parts of the semen Urethra Structure through which urine and semen pass out of body Penis Tube-shaped sex organ; used for reproduction and urination Female reproductive system  Fallopian Tube Endometrium (inside lining) Ovary Uterus – (outside) Cervix Vagina Ovaries Reproductive glands; produce ova and estrogen Fallopian Tubes Four-inch long tube; connects ovary to uterus Endometrium Inner lining of the uterus, thickens to receive the fertilized egg Vagina Muscular tube to outside of body; organ for sexual intercourse; birth canal Uterus Muscular organ; supports fetilized egg during pregnancy; contracts during childbirth Cervix Lowest part of the uterus; connects to vagina Ova: female reproductive cells Estrogen / progesterone: hormones that produce female secondary sex characteristics Ovulation: process of releasing one mature ovum each month Menstration: unfertilized egg and lining of uterus leave body in menstrual flow  Fertility Awareness or “Fertile” Days of a menstrual cycle: Track your period for about 3-4 months. Ovulation occurs about 13-14 days before menstruation begins. The egg cell lives anywhere from 12-24 hours. The sperm cell can live for 3-5 days inside the female reproductive system. During ovulation, the cervix dilates (opens) and the cervical mucus thins to promote fertilization There is an app for everything…