circulatory systems Flashcards
what components are bulk transported by circulation
gases
nutrients and waste
water
hormones
immune cells
what components make up the circulatory system
1) pump (heart/ contractile vessels)
2) vessels (vascular system)
3) medium (blood/maemolymph)
what is the basic composition of plasma
90% or more of water
6-8% plasma proteins
1% inorganic constituents
remaining is occupied by nutrients and waste products
discuss the roles of HDLs and LDLs in mammals
lipids are named based on their ratio of lipid: apolipoproteins
high density lipoproteins= pick up lipids, primarily energy rich diacylglycerides from the gut and from triglycerides breakdown in the fat body
low density lipoproteins = deliver lipids primarily to muscles
what are the major transport functions of vertebrate erythrocytes
1) transportation of oxygen (main function)
2) returning carbon dioxide to the lungs
3) bicarbonate transport
4) H+ transport
5) Nitric oxide transport
6) hydrogen sulphide transport
what is the difference between open and closed circulatory systems
open- in which haemolymph is pumped into extracellular spaces among the tissues bathing the directly for molecular exchange
closed- blood is delivered in vessels which become smaller and smaller until they become leaky capillaries where flow slows down and exchange of materials occurs with body cells
how do circulatory systems overcome the limits of diffusion
by using the process of bulk transport; the movement of the medium that contains the molecules of interest
describe the key events of clotting (without naming every step) and the role of positive feedback
clotting = transformation of blood from liquid into solid gel
ultimate step is conversion of fibrinogen (plasma protein) into fibrin catalysed by thrombin at site of injury which form crosslinks with other fibrin molecules due to factor XIII
what mechanism keep platelet plugs and clots from spreading inappropriately
a clot is not meant to be a permenent solution to vessel injury therefore a crucial anticlotting regulatory process.
when no longer needed it is slowly dissolved by fibrinolytic enzyme called plasmin. Plasmin is activated by a fast cascade of reactions involving many factors and becomes trapped in clot
Describe four different pumping mechanisms for circulation t
1) flagella = internal fluids moved slowly by beating of flagella on epithelia cells
2) extrinsic skeletal muscles= fluids moved by motions of muscles or skeletal elements during locomotion
3) peristaltic muscular pumps = muscles in the walls of vessels contract in a moving wave pushing fluid in front of it
4) Heart = consisting of chamber/s with muscles to squeeze the fluid within, primary pumps of all vertebrates
how do heart valves work
valves ensure the blood flows in the proper direction through the heart
- ensures unidirectional flow, they are psotioned so they open and close passivley due to differences in pressures
- fowards pressure gradient forces valve open
- backwards pressure gradient forces it closed
ATRIOVENTRICULAR VALVE= positioned between atrium and ventricle
SEMILUNAR VALVES= at the junction where major arteries leave the heart
what are intercalated discs and their functions
made up of two membrane junctions desmosomes and gap junctions and allow electricle conduction from cell to cell which trigger heart contraction
Describe how vertebrate heart pacemaker fires rhythmically and how this controls heart beat
pacemaker cells called myogenic cells which do not have a stable resting potential, instead membrane depolarises slowly or drifts between action potentials until thresh hold is met releasing action potentials
what is the plateau phase of cardiac action potentials and why is it important
plateau phase is when cardiac muscle cell membrane is maintained near peak positive level for a while
this prolongs contraction for squeezing the heart chambers
how is fibrillation different from tetanus
