Chp 12: Circulatory System

Question 0

Evolution of heart: Fish hearts

Answer 0

4 undivided chambers
-primitive > "single-circuit pump" gills
-linear arrangement 
-contract from caudal to cranial 
-single stream of unoxygenated blood
-heart mass/body mass ratio low, why?
  •bc they're ectotherms with low metabolism and also they breathe thru delicate gills which could burst the capillaries if the heart pumps too hard and damage the gills

Question 1

Circulation = transport.

What is transported?

Answer 1

O2
CO2 
Nutrients
Hormones
Urea (N waste)
WBC
RBC -> hemoglobin
Platelets
Proteins
Antibodies
Heat (in some)
Water
Dissolved ions

Question 2

4 chambers

Answer 2

Sinus venosus 
-thin wall, receives blood from: common Cardinal veins, hepatic veins
Atrium
-large & thin wall
Ventricle
-responsible for pumping
-thick wall
Conus arteriosus
-short in bony fish and amphibians
-continuous w/ ventral aorta

Question 3

Lungs changed circulation

Answer 3

Tetrapod lungs
 •double circulation
  -(right) low pressure pulmonary circuit (bc lungs are right there)
  -(left) high pressure systemic circuit
•some chambers are partitioned

Question 4

Transitional hearts

Answer 4

(Amphibians & lung fish)
Atrium division
-lung fish + salamanders = partial division
-frogs = complete division

Ventricle division

• lung fish = partial
• all amphibians = none (trabeculae; folding that helps direct blood)

Conus division
-lung fish + amphibians = partial division (spiral valve)

Question 5

Reptile heart

Answer 5

Atrium 
-completely divided
Ventricle
-partial division in many
-fully divided in crocodiles 
-extra chamber in many
Conus = 3 channels
-pulmonary
-left systemic 
-right systemic (left & right like aorta)

Question 6

Crocodilian heart in air

Answer 6

Right ventricle pumps to pulmonary
Left ventricle pumps to both right and left aortic arches
-using foramen (hole) of panizza to connect them

Question 7

Crocodillian heart diving

Answer 7

Right ventricle now shunts blood to body (systemic arches)

Left ventricle continues to pump to body

Question 8

Bird and mammal heart

Answer 8

4 chambered heart
-2 atria & 2 ventricles ; complete divisions 
-left ventricle especially muscular
Conus
-pulmonary + systemic circuit
  •mammals, single left systemic arch
  •birds, single right systemic arch

Question 9

Mammal circulation through heart

Answer 9

Cranial and caudal vena cava> right atrium> tricuspid valve> right ventricle> pulmonary trunk> pulmonary arteries> lung> pulmonary veins> left atrium> bicuspid valve> left ventricle> aorta> systemic circulation

Question 10

Blood vessels

Answer 10

Closed system -blood always in vessels 
Capillaries- some plasma leaks
Lymph vessels
  -collect leaked fluid
  -return it to venous system into subclavian veins

Question 11

Elephantiasis

Answer 11

Lymphatic filariasis

Nematode worms block lymph system

Question 12

Circulatory system characteristics

Answer 12

Variability in anatomy 
Flexibility
  -transport a vein, it will act like an artery
  -tie a part off, other parts enlarge
  -five-fold variation in flow rate
  -shunting (pre-capillary sphincter)

Question 13

Capillaries

Answer 13

Tonica intima, loose epithelial cells one cell thick

Site of materials exchange

Question 14

Arteries

Answer 14

Thick wall, small bore (lumen)
Tunica intima
Tunica media (smooth muscle + elastic)
Tunica adventitia (thick connective tissue)

Question 15

Veins

Answer 15

Thin wall, large bore
Same as artery, only much thinner, no elastic
Valves to prevent backflow

Question 16

Patterns of circulation

Answer 16

Arterial systems

• 6 aortic arches (diff from pharyngeal (cartilage) arch)
• in embryo; differentiate into head arteries

Question 17

Cartilage fish aortic arch

Answer 17

1st arch lost

Rest = branchial

Question 18

Bony fish aortic arches

Answer 18

1st and 2nd arches lost

Rest = branchial

Question 19

Lung fish aortic arches

Answer 19

Like bony fish

Pulmonary artery from 6th arch

Question 20

Tetrapod aortic arches

Answer 20

1st and 2nd arches lost
Dorsal segment dropped b/w 3rd and 4th arches
Arch 3 now carotid complex: cc, ec, ic
4th = systemic (aortic arch)
 -amphibs, reptiles, both R & L 
 -birds only right remain
 -mammals only left remain
5th arch lost in most
6th arch -modified to pulmonary arch

Question 21

Carotid complex

Answer 21

Internal carotid
-3rd arch extends to internal carotids
External carotid
-central aorta extension
Common carotid
-at central base b/w 3rd & 4th

Question 22

Arterial systems

Answer 22

Dorsal aorta- large median vessel
Ventral branches
-celiac artery >stomach
-mesenteric arteries
Lateral branches
-renal, ovarian, testicular 
Dorsal branches
-to muscles, skin
Posterior appendages
-iliac arteries
Anterior appendages
-subclavian arteries

Question 23

Three venous systems

Answer 23

1. Subintestinal = hepatic portal bein in adult
   - drains digestive organs, goes to liver
2. Cardinal
   - drains head, body wall, kidney (renal portal system not in mammals)
3. Lateral abdominal
   - drains posterior limbs, body wall

Question 24

Portal systems

Answer 24

Veins drain organ and dump blood into other organ instead of heart
* hepatic portal

Question 25

Hepatic portal system

Answer 25

Specialized
From embryonic sub intestinal 
Drains capillary beds of intestine, stomach, spleen -> into liver
No need to go to heart first 
Hepatic artery delivers O2 
Hepatic vein delivers nutrients

Question 26

Cardinal system

Answer 26

Primitive, drains head, tail
-anterior + posterior Cardinal veins (& sinuses- pockets of blood)
Subsystem: renal portal
-routes venous blood thru kidneys
-not in mammals
-tail capillaries — renal portal — post Cardinal (fish)
-tail capillaries — renal portal — post cava (Tetrapod)

Question 27

Modifications to basic Cardinal venous system

Answer 27

• mammals lose renal portal
• pre-cava from right common Cardinal (to sinus venosus & right atrium)
• internal jugular from anterior Cardinal veins
• posterior vena cava from (lots of sources) parts of posterior cardinals & parts of renal portal
• azygous vein (very small) from right posterior cardinal

Question 28

Lateral abdominal system

Answer 28

Drains posterior limbs and body wall

Question 29

Fetal circulation

Answer 29

Foramen ovale
-opening b/w atria >bypass lungs

Ductus arteriosus
-connect pulmonary to aorta >bypass lungs

Umbilical arteries (2) -branch from iliac
-out to placenta with wastes 

Umbilical vein (1)
-back to fetus with O2, nutrients

Ductus venosus
-in liver