10.6 The Lymphatic System

Question 1

what is the lymphatic system and what are the 3 functions of homeostasis

Answer 1

lymphatic vessels and organs assiociated w circulatory system
functions of homeostasis:
1. lymphatic capillaries absorb excess tissue fluid and returns to bloodstream
2. lymphatic capillaries absorb fats from digestive tract and transports it to bloodstream
3. lumphoid organs help defend body against disease

Question 2

lymphatic vessels

Answer 2

form a one way system that begins with lymphatic capillaries

Question 3

lymphatic capillaries

Answer 3

tiny, closed ends vessels whose walls consist of simple squamous epithelium
-absorb excess tissue fluid

Question 4

lymph

Answer 4

tissue fluid composed of mostly water, contains solutes (nutrients, electrolytes, O2) and derived from plasma and cellular products (hormones, enzymes, wastes) secreted by cells

Question 5

describe the two ducts the lymphatic capillaries join to form

Answer 5

1. thoraic duct: larger - returns lymph collected from body below thorax and left arm, left side of neck and head into subclavian vein
2. right lymphatic duct: returns lymph from right arm, right side of head, neck into right subclavian vein

Question 6

why are skeletal muscle contractions important in the lymphatic system

Answer 6

lymph forced through lymphatic vessels as a result of muscular compressions prevented from flowing backwards by one way valves

Question 7

edema

Answer 7

localized sweling caused by accumulation of tissue fluid that has not been collected by lymphatic system
-can lead to tissue damage or death is too much tissue fluid made or not drained

Question 8

what are the lymphoid organs

Answer 8

contains lymphocytes which have leukocytes needed for adpated immunity

• primary organs: red bone marrow, thymus
• secondary orgams- lymph nodes and spleen

Question 9

describe the primary lymphoid organs

Answer 9

-red bone marrow: contains network of connective tissue and stem cells capable of dividing and producing blood cells
B lymphocytes remain in bone marrow until they mature
T lymphocytes immature lymphocytes migrate from bone marrow through bloodstream to thymus
-thymus: stop bilobed located in thoracic cavity between trachea and sternum above heart
divides thymus into lobules filled w T cells
-lobules of thymus lined w thymosis

Question 10

what happens to T cells after it leaves thymys

Answer 10

only 5% exit the thymus, these are capable of reacting to foreign molecules
T cells react to body cells undergo apoptosis

Question 11

describe secondary lymphoid organs

Answer 11

-migrate from bloodstream into secondary lymphoid organs, may encounter foreign molecules or cells which they will proliferate and become activated, activated cells reenter bloodstream searcg for sites of inflammation or infection

Question 12

describe the spleen

Answer 12

• upper left side of abdominal cavitity behind stomach
• consist of blood vessels and sinuses
• macrophages remove old and defective blood cells
• lymphoid tissue

Question 13

describe lymph nodes

Answer 13

• small, ovoid structures occuring along lymphatic vessels where lymph passes
• connective tissure divides nodes into nodules
• has B and T cells
• macrophages that engulf pathogens and debris in lymphs

Question 14

name 2 nodes and where they are located

Answer 14

• inguinal nodes: groin

- axillary nodes: armpits

Question 15

what do swollen or tender lymph nodes mean

Answer 15

evidence that body is fighting infection

Question 16

pathogen

Answer 16

disease causing agents such as viruses and bacteria