LESSON 5

• Immunity


  The body's defense against pathogens, a normal healthy individual does not get sick often
• Innate Immunity


  • The body has an innate immunity made up of external and internal defenses
  • Innate immunity has the same response to all types of pathogens even if these have been encountered before
  • Pathogens cannot enter the body easily because of external barriers such as skin and mucus membranes
  • The hair inside the nostrils filters the inhaled air, and the mucus in the respiratory tract catches the dirt and the microbes that come with it

  
• Neutrophils


  Defend the body by ingesting pathogens in a process called phagocytosis
• Macrophages


  Look for cells infected with either bacteria or viruses and phagocytose which consume them

  
• Natural Killer (NK) cells

  • Cancer cells and those infected with viruses can also be killed by natural killer (NK) cells through chemicals that kill cells
  • NK cells protect you from infection and diseases by responding to threats quickly. They destroy harmful cells in the early stages, preventing infected cells and cancer cells from spreading. Having a normal amount of healthy NK cells is an important part of a healthy immune system

  
• Inflammatory Response


  • Wounds trigger inflammatory response which is also part of innate immunity
  • This is characterized by swelling and redness on the surrounding area
  • First, signaling molecules such as histamine trigger increased blood flow to the area which then results in the arrival of phagocytic white blood cells. These cells, together with some defensive proteins, kill microbes and infected cells

  
• Pus


  • Debris of dead cells
  • Together with white blood cells, it will die in the wound healing process
  • It is a thick, discolored (white, yellow, pink or green) fluid that your body makes to help fight off an infection. It consists of white blood cells, dead tissue and bacteria
• Inflammatory Response


  Platelets in the blood plasma form clots to prevent the microbes from infecting other areas, and sealing the wound hastens the healing process
• Widespread infection leads to widespread inflammation
• Prolonged fever with high body temperature greater than 38 ̊C (Normal body temperature is 37 ̊C) is not good, but moderate fever may enhance immune response

  
• To lower temperature, anti-inflammatory medicines are taken to slow down the body's defenses
• Lymphatic system


  • Helps in both innate and adaptive immunity by filtering the circulatory fluid to remove the pathogens and returning the fluid back to the circulatory system
  • Lymph fluid is a clear one which contains less nutrients and oxygen
  • The lymph nodes house lymphocytes and macrophages which kill the pathogens found in the circulatory fluid

  
• The diagnosis of thyroid goiter is made with a comprehensive ultrasound examination of the entire thyroid gland and neck lymph nodes
• Thyroid goiter


  A condition where there is an abnormal enlargement of your thyroid gland
• Adaptive Immunity


  • Mounts defenses against specific pathogens, including those that have been encountered in the past
  • It works when innate immunity fails and triggers a strong and specific immune response
  • However, since it is specific, the same response will not work on other pathogens

  
• Vaccine


  • Contains a harmless part, variant, or piece of a pathogen or a weakened microbe, is given to trigger an adaptive immune response
  • When the real pathogen is encountered, this immune response will be stronger and faster, preventing the person from getting sick
• Antigens


  • Substances found on the surface of molecules such as viruses, bacteria, pollen, dust. Or transplanted organ which trigger and adaptive response
  • The response may be to produce killer cells to synthesize antibodies
• Antibodies


  • Are proteins in the blood plasma which neutralize the effects of antigens
  • Antibodies are proteins that protect you when an unwanted substance enters your body. Produced by your immune system, antibodies bind to these unwanted substances in order to eliminate them from your system. Another word for antibody is immunoglobulin
• The following reasons cause platelet count to drop in dengue-infected patients:
• Humoral Immune Response


  • Protects the body from bacteria and viruses in the blood through the action of antibodies in the blood and lymph
  • Antibody binding makes it easier for phagocytic cells to target the pathogens
  • The antibodies are produced by B cells, a type of lymphocyte
  • "Humor" refers to the body fluids

  
• Cell-Mediated Immune Response


  It employs T cells which responds to pathogens through three different actions: 1. Kill infected cells; 2. Promote phagocytosis by other white blood cells; and 3. Induce B cells to secrete antibodies

  
• Clonal Selection


  • The body has a small number of different sets of lymphocytes which differ in their receptors
  • These receptors are the ones that recognize antigens
  • The first step to adaptive immune response starts when an antigen activates a set of lymphocytes that divide and produce clones grouped into two: 1. One group of cells are called effector cells which attack the pathogens, produce antibodies, and die in the process. 2. The other group of cloned cells become memory cells which will go through the same process when the pathogen is encountered the second time around

  
• Primary Immune Response


  This includes the activation of set of lymphocytes until the action of effector cells

  
• Secondary Immune Response


  • Starting at the action of memory cells
  • This phase starts another round of clonal selection and production of effector cells
  • The secondary response produces the effector cells and antibodies faster and in a bigger magnitude
  • This results in immunity, including lifetime immunity as in the case of vaccines against mumps and measles given to infants

  
• Antibodies


  • Are like superheroes of the immune system, but they do not kill the pathogens directly
  • However, they make work easier for killer cells
  • Antibodies use different mechanisms in order to do their job, to facilitate the death of pathogens through phagocytosis or cell lysis

  
• Create a concept map of the immune system, using the terms below
• Nervous System


  • Central Nervous System (CNS) is made up of brain and the spinal cord
  • Peripheral Nervous System (PNS) brings signals to and from the CNS through nerves and the ganglia
• Nerves


  • Are neurons tightly bound to each other by a connective tissue
  • Nerves are like cables that carry electrical impulses between your brain and the rest of your body. These impulses help you feel sensations and move your muscles. They also maintain certain autonomic functions like breathing, sweating or digesting food. Nerve cells are also called neurons
• Ganglia


  • Are made up of groups of cell bodies
  • "Ganglia" is the plural of the word "ganglion." Ganglia are clusters of nerve cell bodies found throughout the body. They are part of the peripheral nervous system (PNS) and carry nerve signals to and from the central nervous system (CNS)
• Stages of Information Processing

  1. Sensory receptors convey signal in a process called sensory input

  2. The signals are then processed and interpreted, and a response is determine through integration

  3. The response is passed on as signals to the effector cells which carry out the response through motor output
• Knee-jerk Reflex


  • When the knee is tapped, muscles are stretched in that area
  • This information is received by sensory receptors and passed on to the sensory neurons which then conduct the signals to the spinal cord
  • The CNS then directs the message to a motor neuron and interneuron
  • The motor neuron signals a set of muscles (quadriceps) to move the leg forward
  • The interneuron sends a message to another motor neuron to relax the flexor muscles, preventing it from countering the movement of quadriceps
• Neurons


  • Has a cell body containing a nucleus and other organelles. It also has extensions which are responsible for passing on signals
  • Neurons are nerve cells that send messages all over your body to allow you to do everything from breathing to talking, eating, walking, and thinking
• Neurons


  Extending from the cell body are two types of projections: 1. Dendrites are extremely branched short extensions which receive information from other neurons and pass it on to the cell body. 2. Axon are long projections which pass on the signals to other neurons
• Neurons


  • Glial cells are very important partners of the neurons because these cells are the ones that supply neurons with nutrients and keep them insulated
  • An example of Glial Cell in PNS called a Schwann Cell
  • Each bread-like structure in the axon is a Schwann cell surrounded by layers of insulating material called Myelin Sheath
• Neurons


  • In between Schwann cells are gaps called Node of Ranvier. These nodes makes conduction along the axon faster since it is only in these nodes where signals have to be regenerated and not along its whole length
  • Unmyelinated axons convey signals 10 times slower
• Neurons


  • The ends of axons have small branches. The tips of these branches are called synaptic terminals
  • The terminals connected to other neurons from a synapse where the passing on of information occurs
• Nerve Signal Transmission


  1. A neuron is surrounded by ions. Two important neural ions are Potassium (K+) and Sodium (Na+)

  2. When a neuron is at rest, there is a positive potassium on the inside and positively charged sodium ion on the outside

  3. It is very negative on the inside since there is more Cl- on the inside and more NA+ ions on the outside of the neuron
• Neurotransmitter- ACh


  • Acethylcholine (Control muscles)
  • Neurotransmitters are endogenous—produced inside the neuron itself. When a cell is activated, these neurochemicals are released into the synapse from specialized pouches clustered near the cell membrane called synaptic vesicles
• Nerve Signal Transmission


  1. There has to be some sort of stimulus that excites the neuron which is, for example, the ACh like reaching for something

  2. This stimulus will open the channel and take with it the sodium ions
• Nerve Signal Transmission


  1. The sodium will rushed in becoming more positive and positive and positive

  2. As we go up becoming more positive because of the sodium ion entering the neuron, until it reaches -55 which is considered the threshold which generates the action potential

  3. Once reaches the threshold, the neurons fire every time