Immune System - Lymphatic system and the immune system Flashcards
Immunity
Ability to resist damage from pathogens, toxins and internal threats
Immune System
Lymphoid tissues / Lymphatic System
Immune cells
Chemicals that coordinate and carry out immune functions
“self ” from “non-self” - a targeted response
Immune system Functions:
Recognize and remove abnormal “self ” cells
Removes dead or damaged cells
Protects the body from disease-causing invaders
Bacteria, viruses, fungi, protozoans (one cell), parasites
Pollens, chemicals, and foreign bodies
Immunogens: trigger the body’s immune response
Response
Nonspecific Innate Immunity and Specific Acquired Immunity
Lymphatic System
System of vessels / cells / organs that carries excess fluids to the bloodstream and filters pathogens from the blood
drain body fluids and return them to the bloodstream
Lymph: interstitial fluid (fluid that fills spaces between cells) once it has entered the lymphatic system
Function of lymphatic system;
Fluid Balance
Lipid Absorption
Defence against pathogens
Pathogen
Substance or microorganism that causes disease or damage to the tissues of the body
use humans as a source of nutrients and as an environment to survive in
Lymphatic System and Drainage
Tonsils, the lymph nodes, the spleen, the thymus
Lymph nodes -located along lymphatic vessels
Groups in the cervical (neck), axillary (armpit), and inguinal (groin) areas
Lymph: Carries fluid from tissues to circulatory system
Vessels begin as CLOSED-ended capillaries,
Feed into larger lymphatic vessels
Empty into the bloodstream by ducts. –
Lymph travels through the lymph nodes
Doesn’t circulate ie not pumped by heart
Forced through the vessels by contraction of skeletal muscles -
Valves, (one way semi lunar valves)
one-way flow of lymph
Lymphatic System - Capillaries
Where fluid enters the lymphatic system
In virtually all tissues
between arterioles and venules
Thinner walls than veins
Overlapping epithelial ‘flaps’
fluid moves into capillaries only
Lymphatic System: small intestine
Lymphatic capillaries called lacteals
Lipids and some lipid soluble proteins and vitamins form milky fluid = chyle
Enter lacteals
Enter blood stream
Lymphatics Circulation;
Lymphatic capillaries > Vessels > Trunks > 2 ducts
Drainage
Right: Right lymphatic duct drains into right subclavian vein
right sides of the head, thorax, and right arm
Left: Thoracic duct drains into the left subclavian vein
remaining portions of the body
Lymphatic Organs
Tissue: Many lymphocytes / defence cells
Lymphocytes: Red bone marrow
Tonsils
Palatine tonsils
Pharyngeal tonsils (adenoids when enlarged)
Lingual tonsil
Protective ring of lymphatic tissue around the nasal and oral cavities and the pharynx
Pathogens
Lymph nodes
Distributed along the lymphatic vessels
Lymph passes through before entering blood
Superficial or deep
Superficial aggregations
(1) inguinal nodes in the groin, (2) the axillary nodes in the axilla (armpit), and (3) the cervical nodes in the neck.
Dense capsule with extensions: trabeculae
lymphatic tissue: Lymphocytes and lymphatic nodules
lymphatic sinuses: macrophages
Lymph flows through nodes
and activates»_space;>
Activates – stimulating lymphocytes to divide
Nodules: germinal centres
Remove pathogens: macrophages
Lymph flows through nodes
and activates»_space;>
Activates – stimulating lymphocytes to divide
Nodules: germinal centres
Remove pathogens: macrophages
What is the spleen and its role?
Filters blood
Respond to foreign substances, destroy old RBC
White pulp
Lymphatic tissue surrounding arteries
Lymphocytes can be stimulated to divide
Red pulp
Surrounding veins
Macrophages and red blood cells
Macrophages remove foreign substances and worn-out red blood cells through phagocytosis
Also functions as a blood reservoir
Thymus
2 lobed gland
Divided into lobules
Cortex (dark)
Many lymphocytes
Medulla (light)
Fewer lymphocytes
Maturing T-cells
Mature T-cells migrate to medulla, enter blood and travel to other lymphatic tissue
Cells of the Immune System (6 in total)
Circulate in the blood but leave and function extra vascular
(1) eosinophils
(2) Basophils (blood); related mast cells (tissues)
(3) neutrophils
(4) monocytes and macrophages
(5) lymphocytes and plasma cells
(6) dendritic cells
formed in the bone marrow and released into the circulation
Classified: morphologically and functionally
Phagocytes
Cytotoxic cells
APCs
display fragments of foreign proteins on their cell surface
What are Leukocytes?
white blood cells (WBCs): Key cells for immune response
Basophils and Mast cells
Release mediators that contribute to inflammation
Histamine, heparin (anticoag) and other cytokines
Allergic and immune responce
Basophils (circulation)
Mast cells (tissue):
lungs
GI tract
skin
Eosinophils
Allergic reactions and parasitic diseases
Digestive tract, lungs, urinary and genital epithelia, and connective tissue of the skin
Cytotoxic: release substances from their granules that directly damage or kill the parasites
Neutrophils
Phagocytic cells
most abundant WBC
segmented nucleus
Most remain in the blood but can leave if attracted to an extravascular site of damage or infection
Kill / ingest bacteria
release a variety of cytokines
including fever-causing pyrogens
Monocytes and Macrophages
Monocytes precursors of tissue macrophages
Once in the tissues, monocytes enlarge and differentiate into phagocytic macrophages
Key scavengers within tissues
Antigen Presenting Cell (APC)
Antigens: Immunogens that react with B and T lymphocytes
APCs can insert fragments of processed antigen into its membrane - becomes part of surface protein complexes
they can bind to and activate other types of immune cells.
Lymphocytes
Key cells that mediate the acquired immune response of the body
Most in lymphoid tissue
3 subtypes
B Lymphocytes (APCs)
T lymphocytes
Natural Killer cells
Dendritic cells
Long processes
Antigen-presenting cells
Found in skin (Langerhans cells)
Other organs
Once capture antigens migrate to lymph nodes
Present antigens to lymphocytes which activates lymphocytes
Phagocytosis and antigen presentation
> Macrophages and Neutrophils key cells that phagocytose
- Some B lymphocytes and dendritic cells also present antigen
> Some pathogens bind directly to phagocyte receptors / others precoated by antibodies;
- Stimulates internalisation
- Digests pathogen
- Part of it (antigen) presented on surface
What do lymphatic capillaries do?
remove fluid from tissues and absorb lipids from small intensine
Lymph nodes filter _____
lymph
Name lymphocytes;
B cells originate and mature in red bone marrow
T-cells:
Pre-T cells are produced in red bone marrow a
migrate to the thymus and mature to become T cells.
^^ Both circulate to other lymphatic tissues.
B cells and T cells are responsible for much of immunity.
Increase in number and circulate to lymphatic and other tissues
Leukocytes;
Other leukocytes function as phagocytes, granulocytes, cytotoxic cells
