BI108 Quiz 6

immune system

The cells and tissues that recognize and attack foreign substances in the body to keep us healthy

immune system function

recognize self vs. non-self -> activation of "war" machinery -> win the war

lymphatic system

Composed of a network of vessels, ducts, nodes, and organs. Provides defense against infection.

lymph

fluid derived from blood (no red blood cells)

lymph nodes

filters lymph collected from body tossues and returns it to blood

Leukocytes

white blood cells that, as lymph passes through lymph nodes, recognize nonself cells and initiate an immune response

immune system cells

has many types of specialized cells; very diverse

phagocytes

specialized cells of the immune system that can consume/engulf other cells

two roles of phagocytes

1. take in and destroy invading pathogens

2. antigen presenting cells

antigen presenting cells

Cells that display antigens to T cells.

innate defenses

non-specific and always present; 1st line of defense

innate defense mechanisms

skin, mucus, specialized molecules that destroy pathogens, inflammation, phagocytosis

adaptive immune response

relatively slow but very specific and effective immune response controlled by lymphocytes

key traits of adaptive immunity

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

1-2. diveristy and specificity

humans can respond specifically to a lot of different antigens because of T-cell receptors and antibodies

antigen

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

antibodies

protein produced by specialized lymphocytes (white blood cells) that recognize an antigen; either free antibodies or carried B Cell; specific to one antigenw

what happens when antibodies bind an antigen?

- antibody/antigen complexes activate signaling system to attract phagocytes

- ultimately: destruction of 'non-self'

What protein class do antibodies belong to?

immunoglobins

immunoglobins

1. two light chains, and two heavy chains, held together by disulfide bonds

2. each polypeptide chain has a constant region and a variable region

3. variable regions are specific for each antibody; the 3D structure means it will only interact with 1 antigen

3. constant region determines the function and destination

antibody diversity

human immune system can potentiall produce up to one quintillion distinct anitbodies

Antibody diversity is due to

result of gene rearrangements

antibody gene arrangement

- during B cell development: one gene from each cluster is randomly joined and the other genes are deleted

- after transcription, RNA is processed (alternative splicing may occur)

- translation produces functional/only antibody unique to that B celli

immature B cell

wide range of genes part of antibody sequence

embryonic DNA

clusters of genes

DNA recombinanation

gives rise to diversity of immunoglobins; also these genes have a relatively high mutation rate

Each B cell has ...

unique sequence

true/false: each somatic cel have the same identical genome

False; not all somatic cells have the same identical genome

3. distinguishing self from nonself

immune system must be able to recognize all the different 3D cell shapes and not attack them

diversity of cells in a body

all have different 3-dimensional shapes capable of generating an immune response

clonal deletion

elimination of potentially harmful lymphocytes that recognize "self"

autoimmune diseases

result from failure of clonanl deletion; body produces antibody that recognizes self cell as a problem

4. immunological memory

after one response to a pathogen, the immune system "remembers" the pathogen and can respond more quickly and powerfully if that pathogen invades again

vaccination

introduces an antigen and the immune system remembers it

3 phases of adaptive immunity

recognition, activation, effector

humoral immunity

carried out by antibodies in extracellular fluids

cellular immunity

directly targets and destroys infected cells

humoral immune response

1. recognition: T-helper (TH) cells binds to antigen presented by phagocyte; B cells bind antigen

2. activation: B cells are cloned, secrete antibodies into bloodstream

3. effector: antibodies bind to antigens; invading cells destroyed

humoral immunity activation and proliferation

activated B cell divides to create plasma cells and memory B cells

plasma cells

make and secrete antibodies (the same one that detects the antigen originally detected)

immunological memory

ability of the adaptive immune response to mount a stronger and faster immune response upon re-exposure to a pathogen

clonal selection

The process by which an antigen selectively binds to and activates only those lymphocytes bearing receptors specific for the antigen. The selected lymphocytes proliferate and differentiate into a clone of effector cells and a clone of memory cells specific for the stimulating antigen.

cellular immune response

1. recognition: a virus-infected or mutated cell displays antigens, TH with specific receptor binds

2. activation: TH stimulate cytotoxic T cell (TC) with specific receptor to divide

3. effector: TC clones recognize other infected cells, bind to them, and initiate lysis

cellular immunity effector phase

TC cells produce perforin, which triggers apoptosis in target cells

vaccines can "train" the immune system

a second infection by the same pathogen activates memory cells and the immune system responds rapidly

mRNA vaccine

has mRNA to make a protein that is part of the antigen (like a protein on the outside of the virus

mRNA timeline

mRNA sticks around in our cells for only a short period of time then gets degraded

mRNA in cell

mRNA gets delivered to cells in human, those cells create the protein and display it; body creates antibodies to the protein

mRNA antigen piece

completely harmless to our body

mRNA vaccine final steps

- memory cells are created

- an immune response is triggered

mRNA immune response

sometimes can lead to adverse effects (fever); body trying to get rid of the "antigen" even though it is harmless (our immune cells don't know that)

homeostasis

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

what challenges the internal environment?

it is always challeneged by external environment and metabolic activities

main role of homeostasis

maintain optimum physical and chemical environment for all metabolic processes

what does each physiological variable have?

a homeostatic control system

control systems

sense when conditions deviate from 'normal' and initiate physiological mechanisms to correct the error; often involves the interaction of the nervous and endocrine system

components of homeostatic control systems

sensor, integrator, effector

sensors/receptors

provide information; gather information about conditions inside and outside of the body

integrator

obtain, integrate, and process information in a control mechanism

effectors

get issued commands; cause responses that alter conditions in the internal environment

house temperature example

- temperature is the controlled variable

- thermostat is the sensor

- furnace and air conditioner are the effects

- set point is a certain temp (ex: 20 degrees)

set point

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

postive feedback

amplifies a response and increases deviation from a set point (ex: contractions during childbirth)

temperature negative feedback example

1. walk outside in the winter, body gets cold

2. temperature sensors at multiple places in body detects this change

3. info is sent to control center which triggers effector

4. tissues that can generate heat get info (ex: shivering)

5. body heat increases towards normal

homeostatic challenge 1

maintain blood glucose levels

glucose

necessary for proper cell functions; each cell must make its own ATP

blood glucose levels

maintained at constant levels, even though food intake may vary through a day (NEGATIVE FEEDBACK)

key components of maintaining blood glucose levels

pancreas and liver

pancreas

multiple types of cells that each produce/secrete different hormones (insulin and glucagon)

liver

storage of glucose as glycogen

when blood glucose rises above normal...

- error signal: high glucose level

- stimulates pancreas to secrete insulin

- increases circulating insulin (info to effectors)

- uptake of glucose by cells

- use of glucose in metabolism, fat synthesis, glycogen synthesis

- blood glucose level drops

- back to setpoint: regulated blood glucose level

when blood glucose drops below normal...

- error signal: low glucose level

- stimulates pancreas to secrete glucagon

- increases circulating glucagon (info to effectors)

- breakdown of glycogen by liver

- release of glucose to blood

- blood glucose level rises

- back to setpoint: regulated blood glucose level

endocrine system

collection of glands that secrete hormones that control physiological activities (ex: growth, development, response to stress, etc)

signaling through the body

endocrine cells release hormones which travel through the circulatory system and affect distant target

nervous and endocrine systems

they work together; brain controls secretion of many hormones

types of endocrine cells

neurosecretory cells and nonneural endocrine cells

neurosecretory cells

excitable cells that propagate action potentials; cell bodies are in the CNS; the axon terminals release hormones into the blood

nonneural endocrine cells

not excitable; typically stimulated to secrete hormone by other hormones

endocrine signaling

- glands release hormones intor circulatory system (target cells may be far away)

- target cells can have receptors for more than one hormone

- glands may signal sequence of other glands (axis)

- target cells can change a response over time (decrease in receptor number reduces response to a hormone)

- one hormone can trigger different responses in different types of cells

- not permanent

non-permanence of endocrine signaling

hormones may be broken down or removed from the body (filtered out of blood and excreted)

pituitary gland

master gland; secretes hormones that control may other glands, attached to the hypothalamus of the brain; two parts (anterior and posterior)

pituitary gland helps control...

Growth

Blood pressure

Childbirth and breast milk production

Arousal

Thyroid gland function

Metabolism

Water balance

Temperature regulation

hypothalamic-pituitary-adrenal (HPA) axis

a body system involved in stress responses; cells in hypothalamus secrete a neurohormone; which stimulates the anterior pituitary to release a tropic hormone; which travles through the blood to the adrenal cortex, which secretes the hormones cortiso; and epinephrine; which elicits various physiological changes

axis

when endocrine signaling acts in a sequence

neurohormones

secreted by neurosecretory cells (can stimulate or inhibit target); called a releasing hormone when it stimulates the target gland

tropic hormones

control other endocrine glands

hormones

directly stimulate cells/tissues

feedback loops control hormone secretion

hormones can exert feedback inhibition on gland cells, which inhibits hormone secretion

What happens aften an animal obtains O2 from the environment?

it is transported through the body so mitochondria can carry out cellular respiration

What happens to the CO2 produced by cellular respiration?

it is collected from tissues and released at the lungs

bulk flow respiration

when a lot of materials or substances move from one area to another (ex. oxygen going from our lungs to out body)

diffusion

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

fick's law (generalized)

Rate of diffusion per unit of cross-sectional area proportional to C1-C2/L -> difference of concentration/length

Fick's Law of Diffusion

diffusion through a membrane is directly proportional to the surface area and concentration gradient and inversely proportional to the thickness of the membrane and its thickness

variables that limit respiratory gas exchange and all adaptations that maximize respiratoey gas exchange

surface areas, concentration gradient, membrane permeability, membrane thickness

more surface area

faster rate of diffusion