lecture 20 - circulation and body fluids Flashcards
What are open circulatory systems?
Fluid pumped into open ended vessels - fluid can leave the circulatory system
Circulating fluid (haemolymph) bathes cells - doesn’t have haemoglobin because not involved in gas exchange - tubes associated with all cells
Limited control - hard to direct and increase flow to active muscles, but these animals often not that active
What are closed circulatory systems?
Internal (closed ended) vessels
Pump (heart)
Higher pressure
Cells bathed in interstitial fluid
What is extracellular fluid?
ensures adequate function of cell
Important in maintaining homeostasis (e.g. pH & osmolality)
Ionic gradient maintained by Na+/K+ ATPase
Animals with a closed circulatory system have 2 types of extracellular fluid: blood plasma & interstitial fluid
(made of very similar components - blood plasma contains proteins e.g albumin, blood cells (erythrocytes, leukocytes, platelets)
Describe the vessels
where exchange takes place
oxygen out into interstitial fluid from where it goes to cells
short diffusion pathway
arteries have muscle to withstand pressure but veins have lowest pressure as furthest from the heart
Describe the circulatory system of fish
single circulation - only goes through heart once
2 chambered heart - 1 atrium and 1 ventricle
oxygenated at gill capillaries
oxygenated blood is at low pressure because far from the heart- not capacity to deliver lots
oxygen delivered to tissues
deoxygenated blood returned to heart
Describe the circulatory systems of amphibians and reptiles
developed as animals moved on land and became more active
double circulation
3 chambered heart
deoxygenated blood returns to right atrium
oxygenated blood returns to left atrium
both go into common ventricle and mixing occurs
Describe the circulatory systems of mammals and birds
double circulation
4 chambered heart
right atrium- deoxygenated blood pumped to lungs
left atrium - oxygenated blood to body - systemic circulation
