Immune System (Ch 23) Flashcards
Function of the immune system
- Kills infectious organisms
- Recognizes and tolerates self cells and non harmful foreign molecules
- immunological memory to prevent re-infection from same organisms
Parts of the immune system
lymphatic system, thymus, spleen, tonsils, peyers patch, and bone marroe
Function of the lymphatic system
Drains excess interstitial fluid to lymphatic vessels, returns to bloods
When pressure increases in the lymphatic vessels…
spaces between lymph endothelial cells close to prevent fluid coming out
function of the lymph nodes
recognize pathogens and some bacterial toxins that get into the lymph
Edema
from fluid accumulating in the interstitial space
Hypertension (causes of edema)
increased capillary hydrostatic pressure pushes more fluid out of capillaries
Kidney Disease (causes of edema)
kidneys don’t properly excrete salts and water; so build-up occurs
Heart Disease (causes of edema)
Valve failure, obstruction and heart failure causes high venous pressure, lack of venous return
Skeletal Pump (causes of edema)
long periods of standing, immobility/paralysis causes more fluid retention in veins and lymphatic system
Medications (causes of edema)
affect blood pressure, vascular resistance, autonomic nervous system, kidney function and osmotic balance
plasma proteins (causes of edema)
Low albumin can be caused by wounds, burns, liver diseases or malnutrition
Blocked lymph vessels (causes of edema)
due to cancer, infection, inflammation or surgical removal
Red bone marrow
located in central flat bones and ends of long bones
contains hematopoietic stem cells (Pluripotent) that produce red and white blood cells and platelets (Thrombocytes)
Myeloid Lineage (white blood cell)
innate immune system cells, RBCs and megakaryocytes (for platelets)
Lymphoid Lineage (white blood cell)
adaptive (aquired) immune system cells, NKs
B cells (lymphocytes)
Mature in bone marrow then migrates to spleen or lymph nodes\
- responsible for “humoral response”
- phagocytic snd antigen presenting
T cells (lymphocytes)
originates in bone marrow then migrate to the thymus to mature then migrates to spleen or lymph nodes
- responsible for “cell-mediated response”
- recognize microorganisms and viruses by specific antigens on their surfaces
Antigens
part of molecules that cause an immune reaction or immune cells raise antibodies against
Function of B and T cells
recognize self-antigens, our bodies remove the ones that recognize self antigens or harmless substances or our microflora
they react only to specific molecules that match their specific receptors
Negative selection
Thymocytes (immature T cells) that bind the self-proteins are destroyed
Thymus epithelial cells
express self-proteins found in other body regions
Immune cells
B and T cells, macrophages, and dendritic cells
recognize pathogens, some toxins, and dead cells carried in the lymph
Reticular fibres
slow and filter lymph and trap particles that may be recognized by immune cells
Spleen function
filters blood, not lymph, but contains lymphocytes
red pulp (in spleen)
contains macrophages, red blood cells, and platelets. breaks down old red blood cells
white pulp (in spleen)
contains B and T cells, macrophages and dendritic. also contains reticular fibres
Lymphatic nodules
- similar to nodes but not surrounded by capsule
- higher in number where pathogens may enter
- Ex. tonsils, andenoids, Peyer’s patches (gut-assosiated lymphoid tissue (GALT))
Microflora (microbiome)
- microorganisms that normally live on us and in us (don’t cause disease)
- works with our immune system
- helps your immune system to tolerate non-pathogenic microorganisms
- helps fight pathogens by establishing themselves first, limiting available binding sites and resources for pathogens
- also alters the environment to make your body less hospitable
innate immune response
- defense which responds in a non specific way to infection
- doesn’t provide long term protection, but triggers cells involved in the adaptive immune response to provide long term protection
First line of defense is preventing infection
skin and mucus are a physical barrier. and covered with the microflora
Skin
had specialized immune cells throughout its layers to detect invasion or destroy invaders
Musus
found in digestive and respiratory systems (nose hairs also filter particles and induce sneezing)
Skins chemical and physical defenses
- oil glands (sebaceous) make the skin surface acidic
- saliva, sweat, snd tears contains lysozyme that attacks and digests the cell walls of many bacteria
- skin produces RNAase which degrades RNA from microorganisms especially RNA viruses
Digestive/Respiratory systems mechanisms to prevent infection
- saliva contains lysozyme
- Hydrochloric acid and digestive enzymes protect the digestive tract.
- Mucus traps most microorganisms in the respiratory tract, and cilia
continually move mucus up toward the throat (swallowed or coughed
out). - Resident bacteria, normal microflora in the digestive tract, help prevent infections.
Second line of defense
When a foreign pathogen enters the
body, the immune system detects antigens on the surface of the pathogen
cellular and chemical defenses
- Cells that kill invading microbes
- Proteins that alert other cells to the invasion
- Proteins that kill invading microbes
- The inflammatory response
- The temperature response
Cytokines
secreted by Infected cells or those that detect the infection
- signals proteins
that alert neighbours and nearby immune cells to the infection
- positive feedback loop
Autocrine
act on the releasing cell
paracrine
act on nearby cells
Chemotaxis
Innate immune cells move toward the infection following the increasing concentration of
cytokines
Cytokines can cause immune cells to…
proliferate, differentiate, or trigger other functions.
Neutrophils
- Usually the first cells to arrive at an infection. Migrate from the bloodstream through capillaries.
*The most numerous type of white blood cell.
*Secrete cytokines to attract other immune cells and increase vascular permeability.
*Engulf bacteria (phagocytosis) and attack them with enzymes and chemicals in specialized compartments.
Monocytes
are attracted to the infection (chemotaxis)
1. Macrophages
2. Dendritic cells
- both do clean up and antigen presenting.
Macrophages
specialized to engulf and remove microbes and debris from cells or dead bacteria. Clean-up crew. Help dampen the immune response once the infection is over.
Dendritic cells
specialized to display foreign invader’s antigens on their surface to B and T cells
Natural Killer Cells
- kill cancerous and virus-
infected cells by creating holes in
their plasma membranes with
perforin. - The holes allow cell-killing proteins
from the NK cell and interstitial fluid
to enter the cell. - This kills the cell directly or induces
apoptosis. - Macrophages and dendritic cells
then phagocytize the cell debris to
remove it
interferons
- secreted by cells infected by
viruses or bacterial toxins - activate NKs in infected areas
- can activate p53 in infected cells to cause apoptosis
neighbouring uninfected cells respond by
- producing proteins that inhibit viral replication
(true or false) some viruses prevent our cells from making interferons
true
What are parly responsible for making you feel unwell when you are sick?
interferons
plasma proteins made in liver
Inactive state until they encounter a fungi, bacteria or any antibody-covered microbe
Activated complement proteins
- bind microbes and increase phagocytosis
- stimulates mast cells to release histamine which increases vasodilation, vascular permeability, attracts phagocytes
complement proteins
form a membrane attack complex (MAC); makes a pore in the foreign cell’s membrane, fluid rushes in and kills the cell