Circulatory systems

Question 1

Explain the anatomy of a flatworm (platyhelminth)

Answer 1

No heart, blood vessels or blood
*It has a large surface area to volume ratio ( dorso-ventral flattening)
*Short diffusion distance (branches gastrovascular cavity)

Question 2

Jelly fish anatomy compared to flatworm

Answer 2

bigger and more extensive
more branching in gastrovascular cavity.
Muscle contractions

Question 3

Starfish & Echinoderms have a “Cardiac stomach” (~6 bpm)
What are the 3 vessels?

Answer 3

• Haemal system: 3 ring vessels (hyponeural, gastric, genital) Nutrient rather than gas transport
  (no blood)

Question 4

Explain Arthropods & Molluscs and their open circulatory system.
what is the haemolymph?
What is haemocoel?
What is ostia?
What is transported?

Answer 4

haemolymph is equivalent to blood and interstitial fluid
haemocoel is the cavities between organs
ostia; which are little pores that allow movement of haemolymph

They do have a heart with sinuses either sides like chambers
with ostia to haemocoel with a unidirectional flow through pores between them so when the heart contracts it pushes all the haemolymph out of the heart into an area where it all mixes together then when it relaxes it all comes back into the heart. (movement of haemolymph but not systematic)

Some oxygen transport (haemocyanin); mostly nutrients &
nitrogenous waste
* Haemolymph circulate hormones, immune response,
hydraulic system; eusocial nutrient source; adhesive. (works via pressures)

Question 5

Explain the anatomy of a lugworm (polychaete)

Answer 5

• Body ‘hairs’ as gills to take oxygen from surroundings
• Blood vessels in abdomen
• Hemerythrin for oxygen transfer and/or storage

Question 6

Describe the circulatory system of a crayfish

Answer 6

Its incompletely closed

Question 7

How many hearts does an octopus have?

Answer 7

3

Question 8

What does a closed circulatory system have?

Answer 8

Contained in vessels and has a unidirectional flow

Question 9

Explain the circulatory system of most vertebrates

Answer 9

*single in fish, double in mammals and birds
*Blood doesn’t leave veins, arteries or capillaries
*unidirectional flow which allows for more control of blood flow to different systems
*lymphatic system is still open so movement of interstitial fluids in and out of the blood

Question 10

What is the equation for blood pressure and cardiac output?
Which one are mammals and birds determined by?

Answer 10

*Blood pressure= cardiac output x total peripheral resistance
*Cardiac output= (amount of blood pumped by the heart per minute):
stroke volume x heart rate

mammals= cardiac output determined by heart rate
birds and vertebrate= mostly stroke volume

Question 11

What is special about the heart rate of a blue whale?

Answer 11

blue whales can change the rate of their heart beat when they are diving

Question 12

Circulatory system of a fish

Answer 12

Two-chambered heart; single circuit circulation
* Thickness: Sinus venosus (vestigial in mammals) < atrium < ventricle
* Primitive fish: contractile conus arteriosus
* Rest: non-contractile Bulbous arteriosis, acts as a capacitor (steady flow over gills)
* ostial valves prevent backflow

Question 13

What are the two types of tissue surrounding arteries and veins?

Answer 13

Inner=smooth muscle
Outer=connective tissue

Arteries have more smooth muscle so they are stretchier to withstand pressure

Question 14

Pressures in the heart

Answer 14

Systemic circulation= left ventricle
blood pressure measurement=large arteries
systolic pressure=max pressure
diastolic pressure=min

Question 15

Capillaries: microcirculatory system

What substances can travel through pores?
How do lipid soluble substances get through?
What can increase permeability?
What can adrenaline do ?

What is starling equation?

Answer 15

• Permeable:
  *Pores allow small, water-soluble substances in/out (ions, glucose)
  *Lipid-soluble substances diffuse through cell membranes
• Histamine: increases permeability by causing them to contract
• Adrenaline: vasoconstriction of arteriovenous anastomas (direct connections between small arteries and small veins, with no capillary section between them) (AVAs) allows them to be by-passed
• 5-10% capillaries in use at one time

Capillaries: microcirculatory system
* ‘Starling equation’ (more force at the start more hydrostatic pressure. This equation shows the balance of this)
* Hydrostatic pressure:
-Moving, pressure = force/area
-Hydrostatic pressure > osmotic pressure = movement out
* Arteriole end: outward hydrostatic, pressure > inward
-filtration
* Venular end: blood pressure lower
-Reabsorption