Session 7 - Lymphatic and Immune System 1

Question 1

Function of lymphatic system

Answer 1

• Drain excess interstitial fluid and large proteins from tissue spaces
• Transporting dietary lipids and vitamins from GI tract to the blood ( Its role in nutrition)
  
  • Facilitate immune responses - recognise microbes or abnormal cells and responding by killing them directly or secreting antibodies that cause their destruction

Question 2

Excess interstital fluid comes from?

and what happens to it?

Answer 2

At our capillary beds there is a little more filtration than there is absorption and that is the excess interstitial fluid that is then taken up by lymphatic system and returns back to the cardiovascular system.

Question 3

Lymphatic fluid

Answer 3

similar in compostion to interstitial fluid but some differences in (protein) do occur

Major difference is location

Question 4

Lymphatic system consists of

Answer 4

• Lymph: the fluid
• Lymphatic vessels: transport the lymph
• Lymphatic organs and tissue: made of specialized form of reticular connective tissue that contains large numbers of lymphocytes
• Red bone marrow: the site of lymphocyte production

Question 5

Connection of lymph nodes to organs creates

Answer 5

Lymph vessels

Question 6

Lymphatic capillaries unite to form

Answer 6

Lymph capillaries merge to form larger vessels, called lymphatic vessels, which convey lymph into and out of structures called lymph nodes

Question 7

Lymphatic Vessles unite to form

Answer 7

lymphatic trunks and thoracic ducts - vessels are similar in structure to veins but are thinner walled and have more valves

Question 8

Lymph trunks

Answer 8

Lymphatic vessels exit lymph nodes in a particular region of the body, they unite to form lymph trunks

Question 9

Lymphatic vessels ( supply and exit )

Answer 9

There are lymphatic vessels that supply the lymph nodes and also lymphatic vessels that leave the lymph nodes that unite to form lymph trunks

Question 10

Lymph ducts

Answer 10

Lymph passes from lymph trunks into two main channels, the thoracic duct and the right lymphatic duct, and then drains into venous blood.

Question 11

Where are lymphatic capillaries located

Answer 11

Throughout the body along the systemic circulation

• not present in avascular tissue (cartilage, epidermis and cornea), the central nervous system, portions of the spleen, and red bone marrow.
• specialized lymphatic capillaries in the villus of the small intestine, transport digested fats from the small intestine into the blood.

Question 12

Lymph ducts

Answer 12

Lymph passes from lymph trunks into two main channels, the thoracic duct and the right lymphatic duct, and then drains into venous blood.

• Right side - head, arm and chest empty into right lymphatic duct
• Rest of body empties into thoracic duct

Question 13

Thoracic ducts drain lymph into venous blood into

Answer 13

left subclavian vein which in turn return it to the circulatory system via the superior vena cava

Question 14

Right lymphatic duct

Answer 14

Receives lymph from the upper right side of the body

•It drains lymph into venous blood via the right subclavian vein.

Question 15

sequence of lymph flow

Answer 15

blood capillaries (blood)→interstitial spaces (interstitial fluid) → lymphatic capillaries (lymph)→lymphatic vessels (lymph)→lymphatic ducts (lymph)→junction of the internal jugular and subclavian veins (blood)

Question 16

What promotes flow of lymphatic fluid

Answer 16

Respiratory and muscular pumps

Question 17

Fluid and proteins escaping from vascular capillaries (pulmonary blood capillaries, systemic blood capillaries) is collected by

Answer 17

lymphatic capillaries and returned to the blood

Question 18

Lymphatic organs and tissues

Question 19

Primary lymphatic organs

Answer 19

Provide environment for stem cells to divide and mature into B and T lymphocytes - Provide the source of immune cells ( B and T ) that circulate through the lymphatic system.

 Red bone marrow gives rise to mature B cells

 Thymusis the site where pre-T cells from red marrow mature

Question 20

Secondary lymphatic organs and tissues

Answer 20

site where most immune responses occur

Lymph nodes - Acts as filter for the blood and picks up external antigens and external pathogens

Spleen - big site for where red blood cells are digested and recycled. Has a due role, has a big immune function also - Quite a large amount of B cells and T cells in the spleen

Lymphatic nodules/follicles - distribute throughout particular tissues, very important in the gut. Play a huge role in gut immune access.

Question 21

Red bone marrow (primary lymphatic organs and tissues)

Answer 21

oLocation:

•In flat bones and the epiphyses of long bones of adults

Source of red blood cells, source of platelets, source of all the other white blood cells, source of production for B cells, also where they mature before they leave into the lymphatic system and immature T cells.

Question 22

Thymas gland location and function

Answer 22

•Between the sternum and the aorta

Structure -

• 2 lobed organ: Capsule and trabeculae divide it into lobules
• Each Lobules has Cortex (outer) and Medulla (inner)

oFunction:

• Cortex:proliferation and maturation of Immature T cells (pre-T cells) migrated from red bone marrow
• Medulla:Release of mature and immunocompetent T cells into blood to migrate to lymph nodes and other lymph organs

Question 23

Lymph nodes - location and structure

Answer 23

oLocation:

• All along lymphatic vessels
• about 600 lymph nodes, scattered throughout the body, both superficially and deep, and usually occur in groups
• Large groups are present near the mammary glands and in the axillae and groin.

oStructure:

• encapsulated Bean-shaped organs,
• Two parts:

–The stroma: supporting framework of connective tissue

–The parenchyma: functioning part

Question 24

Parenchyma is divided into 2 regions..

Answer 24

1. Cortex: outer and inner
2. Medulla

Question 25

Route of lymph flow through lymph node

Answer 25

Afferent lumphatic vessel (entry) \> subcapsular sinus \> Trabecular sinus \> Medullary sinus \> Efferent lymphatic vessel (exit)

Question 26

Outer cortex of lymph nodes

Answer 26

Consists lymphatic nodules/follicles called a Germinal center –This is the site for B cells proliferation and differentiation into antibody-secreting plasma cells –Also the site for where memory B cells are presented with an antigen by dendritic cells **Swollen lymph nodes** = B cells are growing and making lots of antibodies. Swollen lymph nodes because B cells in the outer cortex are growing and proliferating and antibodies being made and then they are being released into your circulation

Question 27

Lymph nodes - inner cortex and medulla

Answer 27

**oInner cortex:** ‒Consists mainly of T cells and dendritic cells that enter a lymph node from other tissues. ‒Site for T cells proliferation when dendritic cells present antigens to T cells. The newly formed T cells then migrate from the lymph node to areas of the body where there is antigenic activity. **oMedulla:** ‒contains B cells, antibody producing plasma cells that have migrated out of the cortex into the medulla, and macrophages

Question 28

Lymph nodes function

Answer 28

**Acts as a filter** * Many afferent vessels : Few efferent vessels * Slow flow - The slow flow enables the lymph node to sample the lymph, see what's in it - are there any foreign antigens, any viruses, bacteria, * Lymph flows through many lymph glands to increase exposure * Within lymph glands macrophages destroy some foreign substances by phagocytosis and lymphocytes (B cells and T cells) bring about the destruction of others by immune responses. **oSite of proliferation** of Plasma cells (antibody secreting B cells) and T cells. **Simply put -** Site for Where we produce antibodies - when the B cells remember the antigen, or remember a previous infection they turn into a plasma cell and make the antibodies that are designed to bind and destroy the antigen.

Question 29

What is metastasis? Metastasis through lymphatic system - define and give examples

Answer 29

**Metastasis:** The spread of a disease (cancerous tissue) from one part of the body to another. o A characteristic of malignant ( has the abilty to spread - metastasis) tumours * • cancer cells travel via blood or lymphatic system * • cells establish new tumours where they lodge o Secondary tumour sites: can be predicted by the direction of lymphatic flow from the primary site **o Cancerous lymph nodes are enlarged, firm and non-tender** **o Infected lymph nodes are enlarged but not firm and are very tender**

Question 30

Spleen location and structure

Answer 30

**oLocation:** •between the stomach and diaphragm **oStructure:** * the largest single mass of lymphatic tissue * measuring about 12 cm

Question 31

Spleen function ( 2 pulps )

Answer 31

**White pulp:** Lymphatic tissue. B Cells, T Cells and macrophages perform immune function (similar to lymph node process’) **Red pulp:** consists of venous sinuses filled with blood and splenic tissue. Removal of ruptured worn out RBC. Storage of platelets.

Question 32

Lymphatic nodules

Answer 32

oLymphatic Nodules/follicles: egg-shaped masses of lymphatic tissue that are not surrounded by a capsule o**Location**: scattered throughout connective tissue of mucous membranes •Also known as mucosa-associated lymphoid tissue (MALT) oLarge aggregations in specific parts: •Peyer’s patches:In the ileum of the **small intestine**, really important in the **gastronomical tract ( stomach, intestines)** - when we eat any bacteria etc on food the nodules will detect. **•Appendix** **•Tonsils**: form a ring at the top of throat – –Adenoids/pharyngeal tonsil: in the posterior wall of the nasopharynx –Palatine tonsils: at the posterior region of the oral cavity, one on either side –Lingual tonsil: at the base of the tongue

Question 33

Immunity is..

Answer 33

the ability to ward off damage or disease through our defences.

Question 35

What are the 2 types of immunity?

Answer 35

**oInnate (nonspecific) immunity:** defences that are present at birth **oAdaptive/acquired (Specific) immunity:** refers to defences that involve specific recognition of a microbe once it has breached the innate immunity defences.

Question 36

What forms the basis of Innate immunity

Answer 36

Question 37

First line of defence ( innate immunity )

Answer 37

oThe first Line of defence: The external physical and chemical barriers provided by the skin and mucous membranes oPhysical barriers:intact epidermis layer of the skin, mucous membranes and the lacrimal apparatus. oChemical barriers: is localized on the skin, in loose connective tissue, stomach, and vagina.

Question 38

List the components of the lymphatic system

Answer 38

Consists of Lymph (Fluid), Vessels that transport lymph, and organs that contain lymph tissue ( lymph nodes, spleen, thymus, )

Question 39

How do lymph vessels differ from blood vessels?

Answer 39

* The main purpose of lymphatic vessels is to absorb and return lymph fluid from the body back to the blood, and to assist in the body’s immune function. * blood and blood vessels to deliver oxygen and nutrients to organ systems and tissues, and to remove waste products resulting from metabolism.