Exam 3 Bio 101- UNC Chapel Hill

Internal Environment

the interstitial fluid that fills the space around the cell and maintains constant internal conditions

Homeostasis

A tendency to maintain a balanced or constant internal state; the regulation of any aspect of body chemistry.

Negative Feedback

a control mechanism of response in which a stimulus initiates reactions that reduce or revert a change in the internal environment

Positive Feedback

When an external change triggers internal mechanisms that amplify that change

Pathogens

An agent such as a virus, bacteria, or fungus, that causes disease.

immune system

an animals body system of defense against agents that cause disease

Innate Immunity

a set of defenses that are active immediately upon infection and are the same whether or not the pathogen has been encountered previously

Innate External Barriers

skin, acidic environment, secretions, mucous membranes, cilia

If the external innate barriers are breached then what is the second line of defense?

Innate Internal Defense

innate internal defenses

phagocytic cells, natural killer cells, defensive proteins, inflammatory response

Invertebrates rely on what type/s of immunity?

Innate Immunity

Phagocytosis

A type of endocytosis in which a cell engulfs macromolecules, or particles into its cytoplasm.

Steps of Phagocytosis of a Pathogen (5)

1: Pathogens are engulfed

2: They are enclosed in a vacuole

3: The vacuole fuses with a lysosome containing enzymes

4: The pathogens are destroyed by a lysosomal enzyme.

5: Debris from the pathogen is released via Exocytosis.

Vertebrates rely on what type/s of Immunity?

innate immunity and adaptive immunity

Mucous membranes

Membranes that line the surfaces of the body cavity open to the external environment; The mucus secreted protects by trapping foreign particles and killing harmful microbes with defense proteins.

Mucous membranes are found in..

digestive, respiratory, urinary, and reproductive tracts

Cillia (role as an external barrier)

Assist in the airways by sweeping trapped particles away from the lungs

Pathogens that breach a barrier are confronted by two types of innate immune cells:

Natural Killers, and Phagocytes

Natural Killers

Cells that provide an innate immunity system response by attacking cancer cells and infected body cells through the release of chemicals that cause the death of cells.

Phagocytes

A type of white blood cell that ingests invading microbes

Two types of Phagocytes

neutrophils and macrophages

Macrophages

Large phagocytes that go through interstitial fluid, ingesting any bacteria and viruses they encounter.

Phagocytes bear..

Receptors that bind to fragments of foreign molecules shared by a range of pathogens.

Neutrophils

The most abundant type of white blood cell that is circulating in the blood and enters tissues at the site of the infection.

As a Neutrophil destroys foreign invaders it..

self destructs

Complement System

a group of about 30 blood proteins that act together with other defense mechanisms.

The proteins of the complement system...

circulate in the blood in an inactive form

The proteins of the complement system are activated by

substances on the surface of many microbes

The activation of proteins in the complement system can lead to

lysis and bursting of invading cells

cell lysis

rupturing membranes of foreign cells

Inflammatory Response

a major component of innate immunity that functions to disinfect and clean injured tissue

mast cells

Type of white blood cell residing in connective tissue that releases histamine during inflamatory responses.

Histamine

A chemical alarm signal released by mast cells causes blood vessels to dilate and become more permeable in inflammatory responses.

The inflammatory Response Step 1

1: The bacteria activates macrophages; producing signaling molecules that increase blood flow at the injury site, and mast cells release Histamine.

The inflammatory Response Step 2 Part 1

2: Step 1 induces neighboring blood capillaries to dilate and become leaky; fluid passes out of the leaky capillaries and into the affected tissue. Clotting proteins present in blood plasma pass into interstitial fluid along with platelets. These substances help form local clots that help seal the infected region.

The inflammatory Response Step 2 Part 2

Complement proteins attract phagocytes to the area squeezing between the cells of the leaky blood vessell wall; this allows many neutrophils to migrate out of the blood and into the tissue space producing inflammation.

The inflammatory Response Step 3

The neutrophils engulf bacteria and the remains of any body cells killed by them or physically injured.

adaptive immunity

A set of defenses that is activated in response to specific pathogens. It differs between individuals depending on what pathogens they have been exposed too.

Adaptive immunity is..

the second line of defense behind innate immunity.

Adaptive immunity provides what advantages of Innate

stronger highly specific defense.

Antigen

foreign molecules that protrude from pathogens or other particles elicitating adaptive immunity.

Antibody

An immune protein found in blood plasma that attaches to one particular kind of antigen and helps counter its effects.

Adaptive Immune response has memory which means..

it can remember antigens it has encountered before and react against them more quickly and vigorously on subsequent exposure.

Adaptive immunity can be achieved by..

immunization

Active Immunity

Immunity is acquired by receiving an antigen naturally or artificially (vaccine).

Passive Immunity

temporary immunity acquired by receiving ready-made antibodies.

Passive immunity only last..

a few weeks

Lymphocytes

A type of white blood cell that make antibodies to fight off infections

Lymphocytes originate from..

stem cells in the bone marrow

B cells

A type of lymphocyte that completes its development in the bone marrow and is responsible for humoral immune response.

T cells

A type of lymphocyte that matures in the thymus and It is used for cell-mediated immune response.

the humoral immune response response produces

effector B cells and Memory B cells

Nada

Nada

humoral immune response

Produced by B cells, which defend against bacteria and viruses present in body fluids.

cell-mediated immune response

Produced by T cells which defend against infections inside body cells

B and T cells have

antigen receptors

Antigen Receptors

proteins capable of binding one specific type of antigen on the cells surface.

After B and T cells have developed antigen receptors...

they leave the bone marrow and thymus moving via the blood to the lymph nodes, spleen, and other parts of the lymphatic system.

B cells secrete

free floating antibodies into the blood and lymph

Indirect Function of T cells

Promote phagocytosis

B cells bind..

directly to antigens

Epitope

A small surface-exposed region of an antigen where an antigen receptor and antibody binds.

What type of cells Antigen receptors bind to the Epitope

B cells

Antigen Binding Site

The specific region on an antigen or antibody that recognizes the epitope

The binding site and epitope have

complementary shapes

Clonal Selection

an antigen selectively binds to and activates specific lymphocytes bearing specific receptors for the antigen

Once clonal selection is activated...

The lymphocytes proliferate forming a clone of thousands of cells selected to recognize and respond to that specific antigen.

effector cells

Cells that act immediately upon infection and are highly effective at combating an existing infection.

primary immune response

The immune response that occurs the first time a particular antigen enters the body and selectively activates lymphocytes. It takes many days to produce effector cells that secrete antibodies into the blood and lymph in a great enough quantity to overcome infection

Primary immune response makes

memory cells

secondary immune response

when memory cells produced during the primary response are activated by a second exposure to the same antigen.

Secondary immune response is

much faster and stronger than the initial response

Secondary immune response produces

effector and memory cells

What do antibodies do?

Bind to antigens on pathogens to disable and clump them together ready for phagocytosis

2 functions of Antigen-antibody complex in Humoral Response

1. recognize and bind to a specific antigen 2. assist in eliminating that antigen

antigen-antibody complex structure

4 polypeptides in a Y shape

antigen-antibody complex

forms when antibodies bind to antigens

Anti Body mechanisms

Specific recognition and attach phase followed my a nonspecific destruction phase

neutrilization

Antibody bind to antigen then virus cannot stick to surface of host cell

agglugination

clumping together of viruses, bacteria, or foreign eukaryotic cells since each has two antibody binding sites they can hold clumps of pathogen

two modes of reproduction

1. Asexual reproduction

2. Sexual reproduction

asexual reproduction

the creation of genetically identical offspring by a lone parent

Asexual Reproduction Types

budding, fission, fragmentation

Budding

the outgrowth and eventual splitting off of a new individual from a parent

fission

separation of a parent into two or more individuals of about the same size

Fragmentation

the breaking of the parent body into several pieces

Advantage of Asexual Reproduction

Ability to reproduce quickly, no need to find a mate

Disadvantages of Asexual Reproduction

no genetic variation

sexual reproduction

the creation of genetically unique offspring through fertilization

Fertilization

the union of a sperm and egg

gametes

sex cells

sperm

a male gamete that is relatively small and moves by a whiplike flagellum

egg

female gamete that is much larger

zygote

when an egg and sperm join they form this diploid cell

Most animals reproduce via

sexual reproduction

Meiosis and Random fertilization produce

genetic variation

genetic variation provides

Higher survival rates in changing environments, and greater adaptability to changing environments.

invertebrates reproduce asexually when..

there is ample food and temperatures are favorable for rapid growth and development

Invertebrates reproduce sexually when..

The condition in an environment change to be less favorable.

Hermaphroditism

A condition in which an individual has both female and male gonads and functions as both a male and female in sexual reproduction by producing both sperm and eggs.