BI108 Unit 6

what is the immune system’s job?

fight against anything that might be invading it

lymph

fluid derived from blood

the lymphatic system cycle

lymph collects from body tissues, filters through lymph nodes, and eventually returns to blood. as lymph passes through lymph nodes, leukocytes recognize nonself cells and initiate an immune response

innate defenses

non-specific and always present ex. skin: physical barrier/saltiness and dryness

phagocytes

specialized cells of the immune system that can take in and destroy ‘invading’ pathogens

4 key traits of adaptive immunity

diversity, specificity, ability to distinguish self from nonself, immunological memory

antigen

any particle, cell, or molecule that can trigger an immune response

antibodies

proteins produced by specialized lymphocytes that can detect antigens

what happens when antibodies bind an antigen?

antibody/antigen complexes, activate signaling system to attract phagocytes, ultimately destruction of nonself

immunoglobulins

the protein class antibodies belong to

constant region

determines type and recruits other immune system components to destroy antigen

variable region

specific for each immunoglobulin; the 3D structure is responsible for antibody specificity

VDJ recombination

antibody variable region has three segments: V, D, and J; the DNA has many of each, each cell modifies its DNA to cut out all but one of each, so the gene is left with one V, one D, and one J segment

clonal deletion

elimination of potentially harmful lymphocytes that recognize “self”

two divisions of the adaptive immune system

humoral immunity and cell-mediated immunity

recognition of antigen (HI)

antibodies on B cell bind to an antigen, that particular B cell is now activated

activation and proliferation (HI)

that B cell divides to create plasma cells and memory B cells, helper T cells stimulate division

plasma cells

make and secrete antibodies

humoral immunity process

recognition of antigen, activation and proliferation, attack

cell mediated immunity process

recognition of antigen, activation and proliferation, attack

recognition of antigen (CMI)

cytotoxic T cells recognize cells infected by antigen

activation and proliferation (CMI)

that T cell divides to create cytotoxic T cells and memory T cells, helper T cells stimulate division

attack

the cytotoxic T cells have receptors that recognize antigen, once bound, they can directly kill the pathogen/infected cells

homeostasis

the stability of the internal environment, and the mechanisms used to maintain that stability

control system

sense when conditions deviate from ‘normal’ and initiate physiological mechanisms to correct the error

three components of homeostasis

sensors / receptors to provide information, obtain integrate and process information in a control mechanism. issue commands to effectors

set point

a reference point

feedback information

information that is compared to the set point by the sensor

error signal

any difference between the set point and feedback information

effector

tissues or organs that can alter the internal environment

negative feedback

information that returns system to set point

positive feedback

amplifies a response and increases deviation for a set point

endocrine system

the collection of glands that secrete hormones that control prolonged activities

neurosecretory cells

excitable cells that propagate action potentials

non neural endocrine cells

not excitable; typically stimulated to secrete hormone by other hormones

diffusion

results from random molecular motions which causes a net transport of molecules from a concentrated region to a dilute region

fick’s law

rate of diffusion per unit of cross-sectional area

circulatory system

open and closed

open circulatory system

muscular movements facilitate hemolymph movement

closed circulatory system

heart, tubes, blood; function: deliver molecules/nutrients/O2 and remove waste

capillaries

site of exchange between blood and tissues

arteries

away from heart

veins

return blood to heart

oxygenation

when a pigment picks up O2, loading

deoxygenation

when a pigment releases O2, unloading

systemic circuit

brings oxygenated blood to body tissues

pulmonary circuit

brings deoxygenated blood to the lungs

cardiac cycle

cycle of contraction and relaxation of the heart

pulmonary circuit process

right ventricle, lungs, left atrium

systemic circuit process

left ventricle, body, right atrium