Ch. 20 LEC - Lymphatic System

Lecture Exam 2

what are the main parts that make up the lymphatic system?

• lymphatics (a network of lymphatic vessels)

• lymph (fluid)

• lymph nodes (checkpoint areas)

list the functions of the lymphatic system

• return leaked plasma proteins and interstitial fluid to the blood

• base for the immune system

define lymph

the interstitial fluid that enters the lymphatics

define “lymphatic vessels”

one-way system that allow lymph to flow toward the heart

identify the components that make up lymph vessels (lymphatics)

• lymphatic capillaries

• lymphatic collecting vessels

• lymphatic trunks and ducts

in what ways are lymphatic capillaries different from blood capillaries?

• more permeable (to take up cell debris, pathogens, cancer cells)

• have one-way minivalves

• absent from bone, teeth, bone marrow, and CNS

define lacteals

• specialized lymph capillaries present in intestinal mucosa

• absorb digested fat and deliver fatty lymph (chyle) to the blood

how are lymphatic collecting vessels different to veins?

• thinner walls

• more internal valves

• anastomose more frequently (more collateral pathways)

lymphatic collecting vessels:

• collecting vessels in the [ORGAN] travel with superficial veins

• deep vessels travel with [VEINS/ARTERIES]

• nutrients are supplied from branching [STRUCTURE]

skin, arteries, vasa vasorum

define “lymphatic trunks”

part of the lymphatic system that is formed by the union of the largest collecting ducts:

• paired lumbar

• paired bronchomediastinal

• paired subclavian

• paired jugular trunks

• a single intestinal trunk

define “lymphatic ducts”

two main terminal vessels that receive fluid from the lymphatic trunks and return it to the bloodstream

where does the RIGHT lymphatic duct drain fluid from?

• right upper arm

• right side of head and thorax

where does the THORACIC lymphatic duct arise from and what does it drain from?

• arises from the cisterna chyli (in lower abdomen)

• drains the rest of the body (excluding the upper right arm, right side of the head and thorax)

where do the right and thoracic lymphatic duct empty lymph INTO?

the venous circulation at the junction of the internal jugular and subclavian veins

lymph is propelled by _

• pulsation of nearby arteries

• smooth muscle contractions in the walls of the lymphatics

define “lymphocytes”

the main warriors of the immune system

name the main types of lymphoid cells

• T cells (T lymphocytes)

• B cells (B lymphocytes)

what is the primary function of T and B cells?

to protect the body against antigens

define antigen

any substance the body perceives as foreign (e.g., bacteria, viruses, mismatched RBCs, cancer cells)

what is the specific function of T lymphocytes?

• manage the immune response

• attack and destroy foreign cells

what is the specific function of B lymphocytes?

• produce plasma cells (which secrete antibodies)

list the other lymphoid cells (excluding T and B cells)

• macrophages

• dendritic cells

• reticular cells

identify the function of macrophages

to phagocytize foreign substances and help activate T cells

identify the function of dendritic cells

to capture antigens and deliver them to lymph nodes

identify the function of reticular cells

to produce stroma that support other cells in lymphoid organs

list the functions of lymphoid tissue

• to house and provide a proliferation site for lymphocytes

• to furnish a surveillance vantage point

name the types of lymphoid tissue

• diffuse lymphatic tissue (scattered reticular tissue elements in every organ)

• lymphatic follicles (solid, spherical bodies of tightly packed reticular elements)

define “lymph nodes”

the principal lymphoid organs of the body

where are lymph nodes located in the body?

near the body surface in inguinal, axillary, and cervical regions

list the functions of the lymph nodes

• filter lymph: macrophages destroy microorganisms and debris

• immune system: lymphocytes are activated and mount an attack against antigens

summarize the lymph node structure

• outer cortex: filled with dividing B cells

• deep cortex: houses T cells in transit

• inner medulla: final filtration system containing B cells, T cells, and plasma cells

what is the largest lymphoid organ?

the spleen

the spleen is served by the [NAME] artery and vein, which enters and exits at the [STRUCTURE]

splenic, hilus

list the functions of the spleen

• site of lymphocyte proliferation, immune surveillance, and response

• cleanses blood of aged cells, platelets, and debris

• stores breakdown products of RBCs (e.g., iron) for later reuse

• stores blood platelets

thymus:

• size with age

  • in [INFANTS/TEENS/ADULTS/ELDERLY], it is found in the [INFERIOR/SUPERIOR] neck and extends into the [STRUCTURE], where it partially overlies the [HEART/THYROID]

  • increases in size and is most active during [CHILDHOOD/ADULTHOOD]

  • stops growing during adolescence and then gradually atrophies

infant, inferior, mediastinum, heart, childhood

what is the thymus medulla’s function?

regulatory T cell development

how does the thymus differ from other lymphoid organs?

• it functions strictly in T lymphocyte maturation

• it does not directly fight antigens

this organ is the simplest of the lymphoid organs; it forms a ring of lymphatic tissue around the pharynx

the tonsils