Anatomy and Cell Biology 3309 Lecture 21: Histology Lecture 21 - Immune System
2 May 2018
School
Department
Professor
Histology Lecture 21
Immune System
November 28 2017
LEARNING OUTCOMES:
- List components of the lymphatic system
o Lymphatic system is how the immune cells move throughout the body
- Relate the function of lymphatic vessels to their structure
- Describe basic mechanisms of T cell, B cell, and NK cell activation
- Distinguish between diffuse lymphatic tissue, primary lymphatic nodules & secondary lymphatic
nodules
Case Study
58 year-old Rupert McLean presents to a walk-in clinic with a “paint-splatter” pattern of moles on his
forehead. He is Caucasian and his hair is relatively thin on his head. He indicates that these moles have
developed relatively recently. You decide to excise a mole for histopathological analysis. You also draw some
blood from Rupert and look at a blood smear
- What is unusual about Rupert’s blood smear?
- In some cancers, if it is localized it is treatable – depending on the organ, the area can be
removed.
o This is the same case with melanoma. If it is local, it can be treatable.
- BUT since Rupert had many moles – they were worried about the ability of the melanoma cells to
metastasize
What does our immune system do?
- Defense system
- Crucial for beginning part of life until the end of life
- Immune system still developing when you are just born
o Vaccinations work b/c priming immune system
- Immune system is going to target antigens
- Antigen: any substance that can mount a SPECIFIC immune response
o Immune response targeted to just one type of antigen
How is our immune system organized?
- Innate defenses are NOT specific:
o Surface barrier:
▪ Skin
• Major concern with burn victim is infection b/c skin protects the body from
different pathogens
▪ Mucous membranes
• Nasal + oral cavities
o Internal defenses
▪ Phagocytes
• Phagocytosis
▪ Natural killer cells
• Note: develop alongside the adaptive immune
▪ Inflammation
• Key component of immune response
▪ Antimicrobial proteins
• Combined with different mucus membranes + secretions
▪ Fever
• A lot of bacteria will optimally grow at our body temperature (37C) – If we
spike up our temperature, it will decrease the rate of growth of the bacteria
- Adaptive defenses ARE specific
o Humoral immunity
▪ B cells
▪ Antibodies that we are making
o Cellular immunity
▪ T cells
- Note: T cells, B cells + NK cells are lymphocytes
Overview of the lymphatic system
- Lymph fluid is an acellular composition of blood
o Not entirely acellular because there are immune cells BUT no RBC
- Lymphatic system is connected to our vascular system
- Note: lymphatic system and lymph is carrying the immune cells, antigens throughout the body
o We have things set up in our body to intercept if there are any pathogen coming in and
amount an immune response
- Lymphatic system;
o Organs – educators
▪ Thymus
▪ Bone marrow
▪ Spleen*
▪ Note: are called educators because this is where some of our naïve cells, as they are
developing, they are maturing. Not exposed to antigens in these placed but they are
developing (getting educated before they have an immune response)
o Lymph vessels – highway
▪ Connecting different parts of the lymphatic system together
o Cells – effectors
▪ Lymphocytes: B cells, T cells, NK cells
▪ Supporting cells
• Are not immune cells – not developing antibodies or attacking pathogen,
but important for mounting an immune response
o Lymphatic tissues – battleground
▪ Where you develop the immune response. Mature B+T cell encounter their antigen,
have their immune response through humoral or cell mediated immunity & fight off
the pathogen. If it is done effectively (exposed to it previously), you will not notice
you are even sick
▪ Diffuse lymphatic tissue
▪ Lymphatic nodule
▪ Lymph nodes
Document Summary
List components of the lymphatic system: lymphatic system is how the immune cells move throughout the body. Relate the function of lymphatic vessels to their structure. Describe basic mechanisms of t cell, b cell, and nk cell activation. Distinguish between diffuse lymphatic tissue, primary lymphatic nodules & secondary lymphatic nodules. 58 year-old rupert mclean presents to a walk-in clinic with a paint-splatter pattern of moles on his forehead. He is caucasian and his hair is relatively thin on his head. He indicates that these moles have developed relatively recently. You decide to excise a mole for histopathological analysis. You also draw some blood from rupert and look at a blood smear. In some cancers, if it is localized it is treatable depending on the organ, the area can be removed: this is the same case with melanoma. If it is local, it can be treatable.
