Module 3 Flashcards
Lymphatic system actually consists of two semi-independent parts:
1) a meandering network of lymphatic vessels
2) various lymphoid tissues and organs scattered throughout the body
What do the lymphatic vessels do?
The lymphatic vessels transport fluids that have escaped from the blood vascular system back to the blood.
The lymphoid organs house ______ ______ and ________, which play essential roles in _____ ____ and ________ __ ________.
Phagocytic cells and lymphocytes, body defence and resistance to disease.
The function of the lymphatic vessels is to:
Pick up this excess tissue fluid, now called lymph (lymph = clear water), and return it to the blood stream.
Harmful materials that enter lymph vessels:
Bacteria, viruses, cancer cells, cell debris
How does lymph move?
It has no pumping system, its a milking action of skeletal muscle. Rhythmic contractions of smooth muscle in vessel walls and breathing.
Medial iliac lymph nodes:
These are located at the point where the aorta splits in the pelvic region. They drain the pelvic viscera and pelvic limbs
Lateral iliac lymph nodes:
Not always present, located at the bifurcation of the deep circumflex iliac artery
Internal iliac lymph nodes:
Located adjacent to the internal iliac artery, drain adjacent regions
Sacral lymph nodes:
Located ventral to the sacrum, drains the adjacent region
Anorectal lymph nodes:
Located lateral to the rectum, drains the adjacent region
Iliofemoral lymph centre
Located along the course of the femoral continuation of the external iliac artery.
Ischial lymph centre
Located on the lateral aspect of the sacrosciatic ligament, adjacent to the ischial tuberosity
Popliteal lymph center
Located caudal to the stifle and drains the distal limb
Elastin makes up 40% of equine lymphatic vessel walls, assisting them to stretch and contract while on the other hand having fewer smooth muscle cells than those of people. True or False
True
All lymph vessels follow the pattern of the main veins, eventually discharging into a venous vessel - the lumbar duct. True or False
False. Thoracic duct
More closely related to the immune system, what do the lymph nodes do?
They help protect the body by removing foreign material such as bacteria and tumor cells from the lymphatic stream and by producing lymphocytes that function in the immune response.
Explain macrophages.
They engulf and destroy bacteria, viruses, and other foreign substances in the lymph before it is returned to the blood.
Why is the flow of lymph through the node very slow?
Allows time for the lymphocytes and macrophages to perform their protective function.
What happens to a lymph node once it is destroyed?
Nothing since they do not come back.
What are lymphoid organs?
Tonsils, thymus, spleen, peyer’s patches and bone marrow
Spleen:
Located on the left side of the abdomen, filters blood, destroys worn out cells, forms blood cells in the fetus, acts as a blood resevoir
Thymus:
Located low in throat, overlying the heart, functions at peak levels only during childhood, produces hormones to program lymphocytes
Tonsils:
Small masses of lymphoid tissue around the pharynx, trap and remove bacteria and other foreign materials, tonsillitis is caused by congestion of bacteria
Peyers Patches:
Found in the wall of the small intestine, resemble tonsils in structure, capture and destroy bacteria in the intestine, appendix is an offshoot from the large intestine
The thymus is comprised of lobes what are they?
Capsule, Cortex, Medulla
The thymus provides the environment in which stem cells that migrated from the postnatal bone marrow proliferate and differentiate into T-lymphocyte. True or False
True
What is the thymus is referred to?
Primary Lymphatic Organ
What does the thymus do during puberty?
It reaches its maximum size at puberty and then begins to involute. Involution is characterized by gradual depletion of lymphocytes especially of the cortex.
What are more resistant to involution than lymphocytes?
Epithelial reticular cells and thymic corpuscles.
What is the thymus sensitive too?
Radiation and Infection
Bone Marrow:
soft material in the cavities of bones, produces both red and white cells including lymphocytes. T cells and B cells are also produced
What do T cells and B cells do during maturation?
T cells move to the thymus for final development, and B cells remain in the bone marrow. Once B cells are fully developed in the bone marrow, they are also released into circulation and most of them take up residence in the secondary lymphatic organs.
There are two systems that defend our bodies:
1) non specific defence system
2) specific defence system
How does the non specific system work?
Responds immediately to protect the body from all foreign substances.
The non specific defences are provided by:
Intact skin and mucous membranes, the inflammatory response and a number of proteins produced by body cells.
How does the non specific system reduce the workload of the second protective arm?
By preventing entry and spread of microorganisms throughout the body.
What is the specific defence system?
More commonly called the immune system, mounts the attack against particular foreign substances.
The immune system is an organ system rather than a functional system in an anatomical sense. True or False
False. Is a functional system
What are the specific defences structure like?
Its structures are a variety of molecules and trillions of immune cells, which inhabit lymphatic tissues and circulate in body fluids.
What are the more important immune cells?
Lymphocytes and macrophages.
Whats the main difference between nonspecific defences and the immune system?
The immune system must first “meet” or be primed by an exposure to a foreign substance (antigen) before it can protect the body against it.
The acid pH of skin secretions inhibits bacterial growth, and _________ contains chemicals that are toxic to bacteria. Vaginal secretions of adult females are also very ______.
Sebum and acidic.
The stomach ______ secrets hydrochloric acid and protein-digesting enzymes. Both _____ pathogens.
Mucosa, kill
Saliva and lacrimal fluid contain _________. and enzyme that destroys bacteria.
Lysozyme
Sticky mucus traps many microorganisms that enter ________ and _________ passageways.
Digestive and respiratory
The body uses enormous number of cells and chemicals to protect itself. These defences rely on what?
The destructive powers of phagocytes and natural killer cells, the inflammatory response, and variety of chemical substances that kill pathogens and help repair tissue.
Fever is not considered to be a nonspecific response. True or False
False it is considered
When pathogens make it through the mechanical barriers are confronted by?
Phagocytes
Where are phagocytes?
They are nearly in every body organ.
What does a phagocyte do?
Such as macrophages or neutrophils, they engulf a foreign particle much the way amoeba ingests food particles.
Flowing cytoplasmic extensions bind to the particle and then pull it inside, enclosed in a vacuole. Once this happens what does the vacuole do?
The vacuole is then fused with lysosome and it’s contents are broken down or digested.
Why are natural killer cells an unique group?
They are an unique group of defensive cells that can lyse and kill cancer cells and virus-infected body cells well before the immune system is enlisted in the fight.
Unlike lymphocytes of the immune system, which can recognize and react only against specific virus-infected or tumor cells, natural killer cells can act ___________ against any such target by recognizing certain _____ on the intruders surface.
Spontaneously, sugars
Natural Killer cells are not phagocytic. True or False
True
Why do Natural Killer Cells serve to contain viral infections?
So when this is happening the adaptive immune response is generating antigen-specific cytotoxic T cells that can clear the infection.
What are the four cardinal signs and major symptoms of an acute inflammation is:
Redness, heat, swelling, and pain
When cells are injured they release inflammatory chemicals such as?
Histamine and kinnis
What do histamine and kinnis do?
Cause blood vessels in the involved area to dilate and capillaries to become leaky, activate pain receptors and attract phagocytes and WHB cells to the area.
What are chemotaxis?
Cells are following a chemical gradient.
Dilation of the blood vessels increases the blood flow to the area, accounting for the _____ and ____ observed, increased permeability of the capillaries allows plasma to leak from the bloodstream into the tissue spaces, causing local ______ that also activates pain receptors in the are.
Redness, heat, edema.
What is the fifth cardinal sign of inflammation?
Limitation of joint movement.