Last Lecture: Circulation

Front 1

Why is simple diffusion insufficient for delivering oxygen and and nutrients to tissues and remove carbon dioxide and other metabolic wastes from the tissues in large animals?

Back 1

-Diffusion only works over very short distances,so for animals more than a couple of millimeters in diameter, another bulk flow mechanism is needed to transport oxygen from the gills or lungs and nutrients from the digestive system to the tissues. Therefore, diffusion needs to be augmented in large, active animals.

Front 2

What is the name of the pump that pushes blood into large, strong vessels, which subsequently branch and become smaller, but much more numerous as they reach out to the body tissues.

Back 2

-The heart

Front 3

Vessels that bring the blood away from the heart are called...
Their walls are lined with smooth muscle (T/F)...

Back 3

Arteries; True

Front 4

Blood moves through one direction in the arteries, by what 2 mechanisms does it move...

Back 4

-due to high pressure from the heart and by waves of contraction the muscular walls

Front 5

Arteries branch and divide into smaller vessels called...and then to very small...

Back 5

-Arterioles; capillaries

Front 6

Where does diffusion take place?

Back 6

-In the capillary beds; they are spread out throughout all tissues of the body

Front 7

What is the size of a capillary wall and why is this size important?

Back 7

-It is one cell layer thick and about one RBC in diameter; this thckness minimizes the diffusion distance and this diameter maximizes the area in contact with the tissues.

Front 8

How are venules formed?..They continue to merge with other vessels to form..

Back 8

-When capillaries merge; veins

Front 9

How is blood moved through the capillaries?

Back 9

-Blood pressure is reduced by friction with the walls of the capillaries, and it is moved by a venous system by the contraction of surrounding skeletal muscles.

Front 10

Why do paralyzed people need to have their legs moved periodically?

Back 10

-If their muscles don’t function anymore, then there is no contraction to move the blood through the venous system, resulting in venous blood accumulating ins the veins of their legs.

Front 11

Backflow of blood occurs in veins (T/F)

Back 11

-False: backflow of blood is prevented in veins by a system of valves; little flaps of tissue oriented in the direction of blood flow. Any blood moving backwards pushes the flaps closed and prevents backflow of blood through the vein.

Front 12

This principle states that fluids such as air and water are incompressible at biologically relevant speed, meaning that their density cannot change.So, if you have a fluid, such as blood, running through a pipe, it cannot accumulate (which would entail an increase in density) or spread out (a decrease in density), therefore the volume of blood entering a section of the pipe has to equal the volume leaving the section of pipe in any given time.

Back 12

-Law of Continuity

Front 13

If the diameter at one end of a pipe is 2mm and the other end is 5mm, the volume flow rate of the fliud passing through changes from the first end to the exiting end. T/F

Back 13

-False: The volume flow rate is equal to the area of the opening of the pipe times the distance the blood flows per unit time – i.e. the speed of the fluid – and that has to be equal at both ends of the pipe. So we see that the cross-sectional area at one end times the velocity at that end equals the cross-sectional area times the velocity at the other end.

Front 14

So we know that the volume flow rate is equal on both ends of a pipe regardless if they have different cross sectional areas. Would the volume flow rate also remain the same if a pipe was to be branched into smaller pipes?

Back 14

-Yes, The area times velocity in the large pipe is going to equal the velocity times the sum of all of the areas of the small pipes. More cross-sectional area means that the blood is flowing more slowly. (Slide 4)

Front 15

Basic Architecture of Circulatory System (Slide 6)


What are the 4 chambers of the fish heart?

What are their functions?

Back 15

1) sinus venosus: collects venous blood from body

2) atrium: also collecting chamber, but, somewhat thicker than sinus venosus; pumps blood into ventricle

3) ventricle: main pump of the heart; has very thick, muscular walls; contraction of the ventricle increases the blood pressure to drive blood through the circulatory system

4) conus arteriosus: final chamber; also has muscular walls; evens out the flow of blood from the heart and provide a steady supply of blood to the gills, rather than the pulsed flow that results from the strong contractions of the ventricle.

Front 16

How does the blood form the ventral aorta proceed to the dorsal aorta in the fish, i.e. the shark?

(slide 7)
**Should we ask Kristin to go over this one?

Back 16

1. The heart empties into the paired ventral aorta (which carries blood to the gills)

2. Each ventral aorta surrounds each gill chamber with an aortic arch; these aortic arches traveling for the v.aorta to the gills are called Afferent branchial arteries

3. The gill slits surrounded by arteries that collect blood from the capillary beds in the gills called collector loops.

4. These collector loops empty into Efferent branchial arteries that lead to the Dorsal aorta

Front 17

Artery that provides the main blood supply to the brain...it is a branch (an extension) of which aorta?

Back 17

Internal Carotid Artery; Dorsal Aorta

Front 18

Artery that provides blood supply to the mandibular area...it is a branch from the...(hint: surrounds gill slits)

Back 18

External Carotid; collector loop

Front 19

Caudal to the gills the paired dorsal aorta joins to become one single dorsal aorta. As the D.aorta travels caudally, it gives off large, paired...to the myomeres, as well as, unpaired arteries to the gut.
(slide 8)

Back 19

Intersegmental arteries

Front 20

What are the 3 unpaired arteries that travel to the gut, that branch off of the D.aorta?
(slide 8)

Back 20

1. Coeliac Artery (coelom; stomach and liver in pic)

2. Superior Mesenteric Artery

3. Inferior Mesenteric Artery

Front 21

The D.aorta also gives off a series small, paired gonadal and renal arteries, to the gonads and kidneys. T/F

Back 21

True

Front 22

In gnathostomes, the pectoral appendages are supplied by the... and the pelvic appendage is supplied by the...

Back 22

Subclavian artery/vein; iliac artery/vein

Front 23

The subclavian artery becomes the... as it moves into the limb

Back 23

brachial artery

Front 24

The iliac arteries become the... once they enter the limb.

Back 24

femoral arteries

Front 25

As the D.aorta continues into the tail, it becomes the ______ ______.

Back 25

caudal artery

Front 26

How are veins different from arteries?

Give an example of a portal system

Back 26

Veins and arteries pretty much follow the same pattern, except that some veins have to pass through portal systems.


portal system is one in which
deoxygenated venous blood is passed through a second system of capillaries in another
organ. For example, all of the blood that comes from the gut is diverted to the hepatic portal system in the liver so that it can be filtered of toxins and other materials. Blood coming from the
tail is diverted to the renal portal system to deliver blood to the kidneys to remove nitrogenous wastes from the blood.

Front 27

Osteichthyes have 6 aortic arches throughout their entire lives. T/F

Back 27

False: In all osteichthyes, six aortic arches appear during
development, but the first arch is lost during ontogeny.

Front 28

In fish, the _____ _____ branches of the ___ aortic arch and goes into the ____ organ.

(slide 11)

Back 28

pulmonary artery; 6th; gas

Front 29

The portion of the efferent
artery between the pulmonary artery and the dorsal aorta is called the ______ _______.

(slide 11)

Back 29

ductus arteriosus

Front 30

Vein that carries blood from gas organ back to the heart...

Back 30

pulmonary vein

Front 31

Differentiate pulmonary and systemic circuits.

Back 31

Pulmonary circuits bring blood to and from gas organ (lungs) and systemic circuits bring blood to and from the rest of the body.

Front 32

For lungfish, in gill-breathing mode, deoxygented blood is forced through the gills in the 2nd, 5th, and 6th srches and the circulationis ina single circuit, like in other fish. Valves located beyond the affernet artery of the 2nd arch, in the 3 and 4th arches with no gills, and in the pulmonary artery are closed to prevent blood from entering the lungs.
(slide 12)

T/F

Back 32

True =)

**I didn't know how else to make a question out of this, so I put it here for you guys to read.

Front 33

In the lung breathing mode, deoxygenated blood is directed toward the fifth
and sixth arches by a ____ _____ in the conus arteriosus, but a valve in the fifth arch is
closed and the blood is forced through a shunt in the sixth arch that bypasses the gills.

Back 33

spiral valve

Front 34

Amphibians have more aortic arches than fish. T/F

Back 34

False: the aortic arches are further reduced in amphibians, both of the first two arches are lost.

Front 35

The branch of the
dorsal aorta between the third and fourth arch is now known as the _______ _______.

Back 35

Carotid duct

Front 36

After metamorphosis, what changes do we find in the adult amphibian from the larval amphibian.

Back 36

the external gill slits on the third through fifth arches are lost.
Leaving the aortic arches from the third through fifth as direct communication between the D.aorta and V.aorta.


Third arch becomes the internal carotid artery, with the portion of the ventral aorta between the
third and fourth arches now called the common carotid artery from which both the external and internal carotids emerge.

carotid duct is lost in most adult amphibians

sixth arch becomes the pulmocutaneous artery (goes to both lungs and skin); the connection b/w pulmocutaneous artery and D.aorta, the ductus arteriosus, is lost.