immune system pt 1

what are the three layers of immunity against pathogens

physical barriers, innate immunity, and adaptive immunity

ways pathogens gain entry

• inhalation

• ingestion

• broken skin

• sex

• mother to child

• eyes

what does the immune system fight

non-self and altered-self

how does the immune system surveille the body

the circulatory system and lymphatic system

What are the functions of blood

• circulating cells and fluids

• transport nutrients and O₂

• elimination of waste and CO₂

• wound repair

• protection from infection

What are the functions of plasma

• sugars for energy

• clotting factors

• antibodies and other proteins to fight infection

what are the functions of platelets

clotting

What are the functions of red blood cells

O₂ transportation

What are the functions of white blood cells

immune defense

the circulatory system

blood carried through body in vessles through the action of the heart as a pump

arteries role

carry blood away from heart to body tissues

veins role

carry blood back to the heart from the tissues

capillaries

thin wall vessels connect to arteries to veins exchange O₂, nutrients, wastes between blood and tissues

what do white blood cells pass through and what do they get into

through capillaries into tissues

what is the function of the lymphatic system

Drains excess fluid from body tissues as lymph, moves it toward the heart, and carries it through lymph nodes containing immune cells that respond to infections

what are lymph nodes and what do they do?

small structures containing immune cells that help detect and respond to infections

what are the two types of immune defense

innate and adaptive

what type of defense if innante immunity

non-specific

cells of innate immunity

phagocytes, mast cells, natural killer cells

cells of adaptive immunity

B and T cells

what type of defense if adaptive immunity

specific

Where do blood cells come from, and why must they be replenished?

Blood cells come from stem cells in the bone marrow. They have limited lifespans (days to months), so the body must continually make new ones.

How do stem cells develop into mature blood cells?

Stem cells develop into committed precursors. These precursor cells may divide and differentiate into specific types of mature blood cells.

innate immunity role

• preprogramed to respond to infection

  • recognizes general properties of infectious organisms that are different

    than ours

adaptive immunity role

• specifically responds to an individual infection

• remembers how to do it in case of re-exposure

how do immune cells communicate

by secreting proteins. one cell secretes a protein and another senses it and respond

How do immune cells “call for backup”

some proteins recruit more immune cells to the site of the infection

how to immune cells “raise the shield”?

Virus-infected cells release alarm proteins that cause nearby cells to produce antiviral proteins, making them more resistant to infection

during the adaptive response, what coordinates the activites of other immune cells

T_helper

what do innate immune cells detect

PAMPs - pathogen associated molecular patterns

what is PAMPs

physical components of pathogens that do not exist in humans

what is the specific receptors on immune cells that detect PAMPs

PRRs - pattern recognition receptors

How does innate immunity recognize a pathogen?

PAMP bind to PRR → the cell “knows” a pathogen is nearby → engage in fighting

main weapons of innate immune cells

• inflammation

• phagocytosis

• killing by toxins

• calling for backup

phagocytosis role

eliminates foreign cells or bacteria by engulfing them and kill them using toxic chemicals inside the cell, limiting damage to surrounding tissues.

How does the immune system attack parasites that are too large to engulf?

some immune cells can secrete toxic compounds after contact with large parasites

what do adaptive immune system detect

specific pathogens, even ones that don’t currently exists

cells of the adaptive immune system

antibodies and T_killer cells

antibodies are good for

protecting against infections that live outside of your cells

T_killer cells are good for

killing altered self cells - cells infected by viruses or other pathogens

what do each T-cell express

a unique T-cell receptor that will only recognize one pathogen

3 kinds of T-cells and their roles in adaptive immunity

1. CD4 / T-helper cells - coordinate immune system

2. CD8/ T-killer cells - kills infection

3. memory T-cells -  long-lived cells that will remember the infection, allowing a more rapid response the next time that pathogen is encountered

what is APC and their role

antigen presenting cell. they grab pieces of pathogen and present them to CD4 cells

what is an antigen

a small part of a non-self protein

how can one APC find the matching CD4 cell in the entire human body

the lymph node

how does the activation of the CD4 cell occur

when an APC finds a CD4 cell that is specific to that antigen

What is needed to activate a CD4 T cell?

An APC must present the specific antigen that matches the CD4 T cell.

What happens when a CD4 T-helper cell is activated?

1. divide to make more CD4 cells specific to that antigen

2. activate CD8 T-cells and B-cells that are also specific to that antigen

What do CD8 T-killer cells do?

they recognize a specific antigen and kill infected cells or cancer cells

What two signals are needed to activate a CD8 T-killer cell?

1. a signal from an activated CD4 cell

2. a specific recognition of their antigen on on the infected cells

What happens to activated CD4 and CD8 T cells during and after an infection?

1. proliferate

2. leave the lymph node to find infection

3. die when infection is cleared

What are memory T cells, and why are they important?

long-lived T cells that remain after an infection and help the immune system respond faster if it encounters the same pathogen again.

How does HIV infect CD4 T-helper cells?

HIV uses the CD4 protein as a receptor to enter and infect T-helper cells.

How is CD4 cell count used to monitor HIV?

HIV can cause CD4 cell numbers to decline, weakening the immune system and potentially leading to AIDS. A blood test measures CD4 cell numbers to monitor people with HIV.