Capillaries and Lymphatics

Question 1

Why do we have the cardiovas system?

Answer 1

For exchange

Question 2

What are capillaries?

Answer 2

Site of exchange between blood and tissues

Question 3

Features of capillaries

Answer 3

-Very thin walls for efficient exchange
-Large CSA for more exchange
-Unlike the pulsatile flow of the heart, caps have smooth flow

Question 4

Why not thick walls?

Answer 4

They act more as a barrier

Question 5

What are cap cells?

Answer 5

Single endothelial cells that form a tube

Question 6

What does RBC fill up most of?

Answer 6

The lumen of the cap

Question 7

size of RBC

Answer 7

8-10 µm in diameter

Question 8

How does the RBC exchange in the cap

Answer 8

They are so big that they press up hard against the cap wall, making the distance for exchange as small as possible

Question 9

How does endo cell form cap

Answer 9

The Cyto wraps around and connects through a tight junction

Question 10

What determines how leaky a cap is?

Answer 10

How many tight junctions are present

Question 11

Structures through which the blood flows in a cap

Answer 11

The terminal arteriole –> the side branches etc –> the postcapillary venule

Question 12

What does more flow through the cap branches mean?

Answer 12

More heat exchange

Question 13

What are precap sphincters

Answer 13

Can constrict/relax to control the flow of blood

Question 14

How does the precap sphincters send blood to just the venule

Answer 14

Through the matarteriole and thoroughfare channel to the venule by constricting blood flow to the other branches. Aka vascular shunt

Question 15

Metarteriole and thoroughfare channel together are called

Answer 15

The vascular shunt

Question 16

3 types of caps + short def

Answer 16

• Continuous: most common, have tight junctions, the default, forms a continuous cellular barrier and things must go through endo cell
• Fenestrated: somewhat leaky, things dont have to go through cyto
• Sinusoidal: very leaky, very large openings

Last two are for very specific functions only

Question 17

How do you make a cap more leaky?

Answer 17

By changing the structure of the endo cell

Question 18

What are the dots in the cyto of continuous endo cell?

Answer 18

Vesicles that pick stuff from apical side and transports to basal side and vice versa, active process for cellular exchange for stuff that cannot diffuse passively

Question 19

Can gases diffuse passively

Answer 19

Yes

Question 20

Can stuff go through tight junction

Answer 20

yes, depends how leaky

Question 21

What is the thin fuzzy layer

Answer 21

ECM, fuzzy collagen that is connective tissue that acts as an anchor for endothelium tube

Question 22

What do fenestrated caps have?

Answer 22

More porous openings, making it easier to pass through

Question 23

Structure of fenestrated

Answer 23

Thicker parts of endo where nucleus is
- Basement mem that stuff has to pass through
- Fenestrations, floating dots of cyto, stuff passes in between the gaps

Question 24

Size of sinusoidal caps

Answer 24

30-40µm

Question 25

What is incomplete in sinusoidal

Answer 25

The basement layer

Question 26

Structures of sinunoidal

Answer 26

• Smooth endo bits
• Fenestrations
• Larger holes with incomplete basement but holes not large enough to let the RBCs pass through

Question 27

Example of liver cell

Answer 27

Areas that have large holes dont have basement, so liver cells have direct contact with rich intestinal fluid + toxins

Question 28

What do the lymph nodes do?

Answer 28

Where the lymph goes to be surveyed for foreign antigens

Question 29

Functions of the lymphatic system

Answer 29

1. Drains excess tissue fluid & plasma proteins from
   tissues and returns them the blood vas volume
2. Filters foreign material from the lymph.
3. ‘Screens lymph for foreign antigens & responds by
   releasing antibodies & activated immune cells.
4. Absorbs fat from intestine (gut mucosa) and transports to blood as difficult to absorb these through caps

Question 30

Structure of lymphatic system

Answer 30

• Made of endo cells, finger-like projections
• 1. Commence as large, blind ending capillaries.
     
     2. From small intestine (under gut mucosa), a special group of lymphatic vessels called lacteals drain fat-laden lymph into a collecting vessel called the cisterna chyli.
     3. Larger (thin wall) collecting vessels have numerous
        valves to prevent backflow due to low P flow

Question 31

Another name for Cisterna chyli

Answer 31

Milk jug as it noticeable and drains fat rich lymph after a fat rich meal

Question 32

Why do tissues become swollen?

Answer 32

If the lymph cannot drain fluid that has entered the tissues quick enough

Question 33

What drains into the blood vas system through the left subclav vein

Answer 33

Lymphatic collecting vessels on the left side of face, chest and below diaphragm, collect in the thoracic duct and to left subclav (valves at thoracic to prevent backflow)

Question 34

What drains into the right subclav

Answer 34

Lymphatic collecting vessels on the right side of face, chest

Question 35

Where is the Cisterna Chyli?

Answer 35

Next to the Aorta

Question 36

Most common places for nodes

Answer 36

Cerical, inguinal, groin, Axillary

Question 37

Structure of a lymph node

Answer 37

Strands running through it, attatched are immune cells.

Lymph runs through the afferent, bathes immune cells to detect foreign pathogen and leaves through efferent and the drain back into blood vas system

Question 38

Why is breast cancer dangerous?

Answer 38

Cancer cells in the breast can drain into the lymphatics of breast tissue –> up the axillary lumph nodes –> righ lymphatic duct and into the blood vas system through the right subclav vein and metastasise

Question 39

How do we know if cancer has metastasises?

Answer 39

Dye to check if proliferation in lymph, if yes then patient given chemo to treat for possibility of metastasised cancer