This is a distinction level assignment for the new specification of BTEC Applied Science. This is a good guide on how to achieve a distinction grade assignment in this unit
ASSIGNMENT
Learning aim B: Understand the impact of disorders on the physiology of the lymphatic
system and the associated corrective treatments
Description of the gross anatomy of the organs and associated
structures that form the lymphatic system
Primary lymphatic organs generate lymphocytes such as the thymus and bone marrow.
These contain primary tissue that generates B cells and T cells and is the site at which the
lymphocytes undergo the early stages of maturing. Secondary lymphatic organs have tissue
that provides the environment for the antigens to interact with the lymphocytes. This tissue is
mainly in the lymph nodes but can also be found in the spleen and tonsils. Lacteals are also
secondary lymphatic organs and are lymphatic capillaries that absorb dietary fats in the villi
of the small intestines. Valves are found in larger lymph vessels and collecting vessels and
are absent in the lymphatic capillaries. The valves is to prevent backflow of fluid, so that
lymph eventually flows forward instead of falling backwards.
Name Diagram Structure Function
Thymus It is pinkish-grey in colour, This is a specialised
consists of two lobes resing organ that provides a site
in the chest just below the for the generation and
neck and is enlarged during maturing of T
childhood, however it lymphocytes. It regulates
shrinks rapidly after the immune system
puberty. Each lobe contains through the development
many lobules that consist of of cells responsible for
a medulla and an outer cell-mediated immunity.
cortex. The medulla It also controls central
contains larger, mature T tolerance which, when
lymphocytes and the cortex lost causes autoimmune
contains the smaller diseases.
immature T lymphocytes.
Spleen Found in the upper left of The primary function is
the abdomen and made of blood filtration as it traps
two tissue types. Red pulp the old red blood cells
filters blood and contains and allows new ones to
lots of phagocytic cells and pass straight through the
macrophages. White pulp red pulp. It also stores
contains lots of platelets nad can release
lymphocytes and antigen- upto a cup of blood
presenting cells. It also during severe trauma to
contains efferent lymphatic mitigate the effects of
vessels that carry the blood loss
lymph away from the
spleen.
Tonsils Each tonsil has a network The main function is to
of crypts (pits) that store B trap pathogens as they
lymphocytes. There are 4 enter the mouth as a first
pairs of tonsils: adenoid, line of defense against
tubal, palatine and lingual. infection. They contain M
cells that collect the
antigens produced by the
pathogens
, Lymph They are small oval-shaped It acts as a filter for
glands balls of lymphatic tissue lymph and can trigger an
that contain B cells, T cells adaptive immune
and macrophages. They response. Lymph nodes
are divided into lobules, are the primary site for
that contain an outer antigen presentation and
cortex, followed by a activation in the adaptive
paracortex, with the immune response. They
medulla (core) on the also filter lymph fluid and
inside. The afferent the macrophages engulf
lymphatic vessels transport the pathogens so the
lymph into the lymph nodes lymph returns to the
and the efferent vessels blood free of
transport it out. abnormalities
Lymph They are lined with The lymph vessels
vessels endothelial cells and have a transport lymph around
thin layer of smooth the body to the various
muscles and the outer wall lymphatic organs. A
binds the lymph vessels to lymphatic trunk is formed
the surrounding tissue. from the convergence of
Lymph vessels also have many lymph vessels,
valves that prevent the these drain lymph into
backflow of lymph so it can the the lymph ducts
only flow forward. which are the final stage
of the lymphatic system.
Lacteal They are found within the The lacteals allow for
villi of the intestines and are absorption of
a type of lymph drainage chylomicrons into the
vessel. It runs up the centre lymph fluid.
of the villi and joins to the Chylomicrons are a
lymph vessel in the lipoprotein made when
intestinal wall. fatty acids are digested
and emulsified.
Valve They are semilunar Prevent the backflow of
structures that attach to lymph and pump it
opposite sides of the lymph towards the heart to
vessel. Lymphatic return the lymph fluid to
capillaries do not have the blood by the
valves. subclavian veins.
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