lymphatics and tissue exchange

Question 1

intrinsic control of arterioles

Answer 1

Control of local blood flow:
-level of metabolites in surrounding tissue (CO2=dilate)
-Autoregulation (steady blood flow to tissues despite changing arterial pressures)
-Active hyperemia (increase in metabolism/demand of organs causes dilation and increased blood flow)

(Arterioles usually determine total peripheral resistance by controlling flow of blood into capillaries into organs)

Question 2

Extrinsic control of arterioles

Answer 2

Sympathetic Nervous System

Endocrine System (Angio II and NE are strong hormones causing vasoconstriction)

Question 3

Why is simple diffusion the most common way to cross the capillary walls?

Answer 3

Simple squamous cells take up more surface area than the small clefts in between them

Moving through clefts: must be water soluble (ions, glucose, amino acids)

Moving across membrane: must be lipid-soluble gases such as O2 and CO2

Question 4

What organs are the exceptions to requiring vesicular transport?

Answer 4

Kidney and Intestine: fenestrated capillaries allow for larger proteins to move across

Question 5

Why doesn’t water always follow sodium ions?

Answer 5

ex: certain parts of the kidney are non permeable to water (aka don’t have aquaporins)

Question 6

Blood Hydrostatic Pressure

Answer 6

Pressure that is exerted by fluid within an enclosed space (capillary or interstitial)
-capillary hydrostatic pressure pushes fluid out of capillaries, interstitial hydrostatic pressure pushes fluid into the capillaries

Question 7

Oncotic Pressures (AKA colloid osmotic pressure)

Answer 7

Caused by proteins, which pull fluid towards them
-most proteins are inside capillary (normally very little in interstitial spaces)

Question 8

What do you call the buildup of fluid in interstitial spaces?

Answer 8

lymphedema

Question 9

Filtration coefficient and Reflection coefficient

Answer 9

FC: water permeability of capillary walls

RC: Capillary’s permeability to proteins

Question 10

Causes of Edema: Heart Failure

Answer 10

Blood cannot get pumped out efficiently, so it backs up in capillaries

This increases the capillary hydrostatic pressure causing fluid to leak out into the lower limbs
-why lower limbs? less return to the heart
-(elevating the feet with edema can help return blood flow to the heart)

Question 11

Causes of Edema (cont.)

Answer 11

Infections, toxins or burns
-cause clefts to become larger form the damage, thus increasing the filtration coefficient and letting more water out

Question 12

Causes of Edema (cont.)

Answer 12

Blockage of lymph system
-allows proteins to build up in interstitial space
-increases the interstitial oncotic pressure
-pulls water out of capillaries
-lymphedema occurs

Question 13

Causes of Edema (cont.)

Answer 13

Decrease in plasma protein
-liver failure (creates proteins)
-Protein malnutrition
-Kidney disease

All of these situations result in decreased capillary oncotic pressure due to lack of proteins in the bloodstream
-Same result as protein buildup in lymph, just different process

Question 14

3 types of passive transport

Answer 14

-Diffusion
-Facilitated diffusion
-Osmosis

Question 15

T or R: Facilitated Diffusion used non-specific channels as well as very specific channels

Answer 15

T

Question 16

Active Transport: 2 types

Answer 16

Primary: Uses ATP (sodium/potassium pump [3 Na+ out, 2 K+ in])
-against concentration gradient

Secondary: Does NOT use ATP, instead uses electrical gradient produced by primary (Na/K pump which produces gradient)

Question 17

how is lymph fluid moved throughout the lymphatic system?

Answer 17

Pulsation of nearby artery and skeletal muscles (like skeletal muscle pump, also has valves)

Question 18

Purpose of lymphatics

Answer 18

Return fluid/large molecules to the heart

Immune surveillance/blood filtration

Question 19

Everyday about 20 liters of fluid leaks out of cells into interstitial spaces. About 17 liters quickly get reabsorbed. What happens to the remaining 2-3 liters?

Answer 19

Returned to the blood stream (dumped into veins) by lymphatic system

Question 20

Lymphatic vessel anatomy:

Answer 20

Capillaries are very permeable: made up of single endothelial cells that loosely overlap and form one-way minivalves

capillaries are secured by collagen filaments allowing them to be flexible but maintain shape

Question 21

Movement of lymph:

Answer 21

Lymph capillaries

Lymph vessels

Lymph trunks

Lymph ducts

Question 22

Lymph system: 9 trunks (named after area they drain from)

Answer 22

TEST: see lymph system pwpt slide 10 (Image)

2 lumbar trunks
2 bronchomediastinal trunks
2 subclavian trunks
2 jugular trunks
1 intestinal trunk

From the trunks it drains to the ducts

Question 23

2 major lymphatic ducts:

Answer 23

Right lymphatic duct:
-collects lymph from right arm, right side of head and chest
-drain into the junction of the right jugular vein and right subclavian vein

Thoracic duct:
-collects from everywhere else in the body
-Drains into the junction of the left jugular vein and left subclavian vein

Question 24

Side Note: Gut Associate Lymphoid Tissue (GALT)

(NOT test material)

Answer 24

The gut-associated lymphoid tissue (GALT) is the largest mass of lymphoid tissue in the body. It consists of immune cells such as B and T lymphocytes, macrophages, antigen-presenting cells, including dendritic cells, and specific epithelial and intra-epithelial lymphocytes.

Question 25

Where will you find diffuse lymphoid tissue?

(MALT: mucosa associate lymphoid tissue)

Answer 25

GI tract and respiratory tract

Question 26

Where will you find lymph nodes?

Ruzga: “most people know where most of these are”

Answer 26

Axilla
Cervical
Inguinal
Occipital (pony tail tension)
Pre-post auricular
Peyer’s patches (intestinal wall)

Question 27

If a pathogen gets into the lymph system:

Answer 27

A dendritic cell (antigen-presenting cell, ex: B cell) will detect it in a lymph node

Antibodies can be made, T cells can respond, etc.

Question 28

Spleen:

Answer 28

Receives and filter blood NOT lymph

White pulp: antibody-coated bacteria are filtered out after reacting with an antigen

Red pulp: where old and defective blood cells are destroyed
-heme and iron are broken down and recycled

ALSO stores RBCs and platelets to be released in stress

Question 29

If we remove the spleen, what are we worried about?

Answer 29

Maybe a bit more anemic because no reserve of RBCs and platelets. Also concerned about infections that might not be recognized as easily. Why???

Question 30

Thymus

Answer 30

located in upper part of chest in neonate up to puberty then is replaced by fat

When we lost the thymus, where are T cells made? (don’t forget they mature in bone marrow)

Question 31

Tonsils

Answer 31

Tubal
Adenoid
Lingual
Palatine

-Trap pathogens in food and air
-Known as Waldeyer’s ring
-Much more painful in adults to get removed
-Most common tonsil removal is palatine