Lecture 13/14: Support and defence system

Question 1

What are the various lines of defence? what type of defence are they?

Answer 1

Nonspecific defence (inniate immune system):

• First line: nonspecific physical and chemical surface barriers
• Second line: Nonspecifc internal cellular and chemical defense

Specific defence:
Third line: immune response

NOTE: if pathogen penetrates first defence then goes to second and if survives second goes to third

Question 2

What are examples of the first line of defence?

Answer 2

• tears: proects against substances in eyes
• skin: physical barrier to outside
• Large intestine: normal bacterial inhabitants prevents invaders
• Saliva: washes awa microbes
• Respiratory tract: mucus traps organisms
• Stomach: acid skills organisms
• Bladder: urine washes microbes from urea

Question 3

What are examples of second line of defence?

Answer 3

• identify foreign matter but isnt specific, doesn’t develop memory
• defensive cells, protein,s inflammation and fever

Question 4

Explain protein based defence

Answer 4

• called lysis
• mainly in liver, released in inactive form
• deactivated by native proteins
• become activated by: polysaccharides on bacteria surface or antigen/antibody complexes (adaptive immune response)
• acts in digestive way, creates holes and fluid rushes in causing invader to burst
• in brain has similar system made from glial cells
• complement attacks the plaque and neurofibrillary tangles (common for alzheimers and neurodegradation)

Question 5

How does inflammation workq

Answer 5

• foreign object found
• histamine is released
• capillaries opened, inc blood flow carrying defence cells and chemicals causing redness
• heat due to inc in metabolic rate
• swelling due to fluid containing defensive chemicals
• pain prevents movement allowing it to heal
• can also occur as response to tissue damage, stress, arthritis, obesity

Question 6

How does a fever work?

Answer 6

• infection or toxins cause release of monocytes/macrophages then **pyrogenic cytokines
• gets into hypothalamus and resets thermoregulatory point
• why you get hot

Question 7

How does the support and defence system defend against more than just invading microbes

Answer 7

• part of CNN, SDS always on doing multiple things and is “watching” for invaders
• protects against local tissue damage not due to infection
• normal tissue turnover (cell death, regeneration during wound healing
• appearance of transformed cell populations (cancer)

Question 8

How does the support and defence system relate to obesity?

Answer 8

• adipocytes increase number (hyperplasia) but also in size HYPERTROPHY
• cell gets too big for capillaries and oxygen cant get to it
• lead to reduced blood flow/hypoxia and cell death
• Macrophages infiltrate these areas, recruited by kind of stress signal (MCP-1)
• macrophages release inflammatory peptides such as TNF, IL-6 that cause insulin resistance in surrounding tissues such as muscle

Question 9

How can insulin resistance in small amounts be beneficial for SDS and obesity

Answer 9

• insulin promotes glucose uptake
• dont want tissues to take away energy, want tissues to get it
• if it becomes chonic and constant macrophages can lead to diabetes

Question 10

Where do macrophages infiltrate?

Answer 10

• areas of reduced blood flow/hypoxia
• adipocytes
  skeletal muscle (in obese individuals)

Question 11

What are parenchymal cells

Answer 11

• think “parent”
• functional cell, are the critical functional portion of the tissue (gland/organ)
  ex: liver, skeletal muscle, heart, brain, adipose tissue, pancreas

Question 12

What are stromal Cells

Answer 12

• non parenchymal cells
• framework and support for parenchymal cells
  form support and defence system
  ex: neurons, astrocytes, fibroblasts, stem cells, gap junctions

Question 13

What stromal changes occur during the development of pancreatic cancer

Answer 13

increase in sensory and SNS nerve fibers, macrophage infiltration, capillary density

Question 14

What is MHC

Answer 14

major histocompatibility complex

- like a flag pole, holds an antogen that is either self or non self

Question 15

What is an antigen

Answer 15

a molecule often on surface of a pathogen that the immune system recognizes as a specific foe

Question 16

How does memory in the support and defence system work?

Answer 16

1) invader enters body
2) macrophage encounters, engulfs and digests the invader
- macrophage places a piece of invader (antigen) on its surface with the MHC marker
3) Alert: macrophage presents the antigen to a helper T cell and secrets a chemical that activates the T cell
4) alarm: activate T cell (effector helper T cell)
- activates into either naive cytotoxic T cell or a naive B cell

** slide21 of lec 13/14

Question 17

How can T cells detect a foreign antigen

Answer 17

• cannot detect if circulating freely in the body
• must be displayed on a MHC.
• ability to trigger a T and B cell response to foreign antigens requires macrophages

Question 18

What happens to the Helper T cell once it is activated?

Answer 18

• turns into effector helper T cell (means activates) it can either
  1) turn into Naive B cell
• building specific defences, cell divides
• plasma cell secretes antibodies targeting pathogens or toxins outside of cells
• like missile response, is not direct
  2) turns into naive cytotoxic cell
• builds specific defences and turns into effector cytotoxic cell
• targets cells infected with intracellular pathogen (cancer cells/cells of organ transplants)
• finds cells displays foreign antigen, kill by chemical means (perforins punching holes in target cell membrane like compliment)
• engages directly

Question 19

How does memory play a role in subsequent encounters with pathogins

Answer 19

• memory B cells and memory cytotoxic cells are created
• first exposure to antigen will often get sick
• second exposure has a much stronger response to antigen because of memory cells

Question 20

How is negative feedback involved with T cells

Answer 20

• T suppressor cells suppress activation of immune system, particularly production of T helper cells
• Too little T suppressor response: association with autoimmune disease, allergies, graft rejection, inflammatory bowel disease
• too much T suppressor response: possible connection to cancer and increased incidence of infectious diseases

Question 21

How are glial cells used for protein based defence?

Answer 21

• glial cells in brain recognize neurofibrillary tangles and plaque (brains form on compliment)
• tangles and plaque are characteristic of alhziemer’s disease leading to neurodegredation

Question 22

What are neutrophils

Answer 22

• type of phagocyte
• first on scene and consume bacteria
• method of cell based defence

Question 23

What are macrophages

Answer 23

• phagocytes
• consume almost anything
• method of cell based defence

Question 24

What are Eosinophils

Answer 24

• discharge enzymes that digest

- non phagocytes

Question 25

What are NK cells

Answer 25

• constantly circulate and patrol for non-self, prime targets are cancer cells. Release perforin and proteases to destroy cells
• non phagocytes