Lecture 5 circulation

Question 1

agnatha and elasmobranchii circulation(4 steps)

Answer 1

1.heart
2.ventral aorta
3.gills
4.dorsal aorta

Question 2

teleost circulation (4)

Answer 2

left and right branches of dorsal aorta

caudal heart aids venous return in many teleosts (except Acanthopterygii) & elasmobranchs

secondary circulation supplies capillary beds in epidermis of exposed portions of scales - may contain 50% plasma

few erythrocytes, function poorly known

Question 2

whats in fish blood (6)

Answer 2

erythrocytes (red cells) except for leptocephalus, eel larvae, Antarctic channichthyids

leukocytes (white cells) for clotting and immune functions

nutrients

hormones

antifreeze glucoprotein or glucopeptide in some species

hemoglobin : protein (globin’s) can vary between species

Question 3

bohr effect (3)

Answer 3

Higher O2 uptake rate of Hemoglobin at high pH
-H+ ions bind and change the shape of molecule
-O2 more readily lost to respiring tissues at low pH (affects rate)

Question 4

root effect (2)

Answer 4

Root Effect : reduced pH may also limit maximum O2 binding

especially important for fish with swim bladders

Question 5

the heart (3)

Answer 5

-coordinated muscular contractions and valves to prevent backflow

Elasmobranchs have contractile conus arteriosus with valves

Most teleosts have their conus arteriosus reduced with single valve
-bulbous arteriosus maintains constant pressure
through heart contractions (expands up to 700x
in carp)

Question 6

branchiostegal pump (2)

Answer 6

negative pressure pump has 2 parts:

buccopharyngeal cavity (‘inside of mouth’)
parabranchial cavivity (between gills & operculum)

Question 7

waterflow (3 steps)

Answer 7

mouth opens & buccal cavity enlarges - water in

parabranchial cavity enlarges - water over gills

mouth closes, cavities contract - water over gills and out operculum

Question 8

gill flow structure (3)

Answer 8

arterioarterial flow provides O2 to body-afferent artery -> lacunae & central sinus -> efferent artery

pressure drops (30% - 60%) between ventral & dorsal aorta

arteriovenus flow (not illustrated) for nutrients to lamella
bone and pilaster cells structurally support lamella

Question 9

gas bladder ecology

Answer 9

Benthic forms - often lacking
Marine, narrow depth range - ~5% volume
Freshwater (typically)- ~7-10.6% volume
Streams - smaller than still water species

Question 9

gas bladder ecology

Answer 9

Benthic forms - often lacking
Marine, narrow depth range - ~5% volume
Freshwater (typically)- ~7-10.6% volume
Streams - smaller than still water species

Question 10

gas bladders

Answer 10

physostomous (pneumatic duct)
sometimes air breathing e.g. mudskippers

physoclistous (“closed”)
gas exchange and buoyancy via circulatory system alone