BIO W12: Animal form and the immune system I

three principles of physiology

• form

• function

• regulation

physiology

study of processes and function of an organism and connections between:

• form

• function

• regulation

form

anatomy

function

contributions to survival

regulation

coordination and control

four levels of organization of the vertebrate body

cells in tissues are embedded in an extracellular matrix

cells in tissues are connected by different types of junctions

tight junction

seals neighboring cells together in an epithelial sheet to prevent leakage of extracellular molecules between them; helps polarize cells

adherens junction

joins an actin bundle in one cell to a similar bundle in a neighboring cell

desmosome

joins the intermediate filaments in one cell to those is a neighbor

gap junction

forms channels that allow small, intracellular, water-soluable molecules, including inorganic ions and metabolites, to pass from cell to cell

hemidesmosome

anchors intermediate filaments in a cell to the basal lamina

organs are composed of different tissues

• epithelial

• connective

• muscle

• nervous

regulation

coordination and control

endocrine system

• hormones move in circulation

• slower acting

• can have long-lasting effects

nervous system

• neurons transmit information

• faster acting

• more transient effects

coordination and control often act to maintain homeostasis

cell function requires that internal body conditions be relatively constant

• homeostasis

• ex: body temp, blood pH, and glucose concentration

homeostasis

steady state physiological conditions of the body

negative feedback

• change triggered response that counteracts change

• maintain homeostasis

positive feedback

• change triggers response that enhances change

• promotes rapid change

regulating body temperature

temperature regulator

internal control of temp independent of external

temperature conformer

internal temp equals external temp

temperature sensor in humans

• in hypothalamus

temperature regulation

regulated by the circadian clock

circadian clock

• cycle of ~24 hrs that persists without external cues

• regulated by a negative feedback loop

first demonstration of the power of vaccination

administration of antigenic material to stimulate innate and adaptive immunity to protect against subsequent infection

pathogens

microbes that cause disease in healthy people

immune system

recognizes pathogens and responds with immune cells and proteins

innate immunity

earlier response

adaptive immunity

later response

innate and adaptive immunity

phagocytosis

the process of cellular “eating”

neutrophil

a phagocytic cells that is a component of the body’s first cellular line of defense. Attracted to tissues during inflammation

killing microbes by phagocytosis

contributors to the microbial killing in phagocytes

• enzymes that degrade microbial components

• toxic variants of oxygen and nitrogen

• antimicrobial peptides that lyse microbes

• deprivation of key minerals such as iron

local response to infection step 1

histamines and cytokines released. capillaries dilate

local response to infection step 2

antimicrobial peptides enter tissue. neutrophils are recruited

local response to infection step 3

nuetrophils digest pathogens and cell debris. Tissue heals

innate immune recognition

each of a small set of receptors recognizes a molecule absent from animals, but common to a type of pathogen

toll-like receptors (TLR) recognise PAMPs to stimulate the overall immune response

PAMPS → cytokines production → fever and adaptive immune response

PAMPS(pathogen associated molecular patterns)

conserved molecules of pathogens

tests to determine whether TLRs function in the innate immune response to pathogens

• test whetehr a mutation in a TLR gene in the fruit fly causes susceptibility to fungal infections

• test whether a mutation in a TLR gene in mice causes susceptibility to bacterial infections

• examine the innate immune response in humans carrying mutations in TLR genes

mutation in TLR4 gene confer reduced responsiveness to the bacterial product LPS

lymphatic system

• global response to an infection