Blood Flashcards
What are open an closed circulatory systems?
Open: blood not always in vessels, closed: blood always in vessels
What is the difference between constrict and contract?
Contract = becomes shorter, constrict = becomes narrower
How does blood flow in insects where there is a muscular pumping organ similar to the heart?
long, muscular tube under the dorsal (upper) surface of the insect, blood enters heart through pores: ostia, heart pumps blood towards head by peristalsis, blood pours into body, bathes tissue
What do larger/more active insects have attached to their hearts?
Locusts, open ended tubes attached to direct blood flow towards active body parts like leg/wing muscles
How is it possible for insects to survive with an open system?
Small, blood doesn’t travel far and doesn’t have to transport O2 or CO2 (separate system for this)
Why would an open circulatory system not be sufficient in a larger organism?
Blood needs to transport O2 and CO2 and blood pressure is too low, flow is slow, parts of the body wouldn’t receive sufficient O2 or nutrients
What is the purpose of tissue fluid? What does this enable the heart to do?
bathes tissues and fluid, heart can pump blood at a higher pressure so it flows quicker
What system do fish have?
Single, closed system, blood stays in vessels: heart to arteries to gills to veins to body to veins to heart
What do all types of blood vessels have?
Inner layer/lining, made of single layer of cells: endothelium, smooth to reduce friction with flowing blood
In a cross section of an artery, what are the different layers from inside to out?
lumen, endothelium, elastic fibres, smooth muscle, collagen fibres
Which way do the arteries carry the blood? How high is the blood pressure?
Away from heart, high pressure so artery wall has to withstand pressure
What are the lumen and wall of the artery like?
Small lumen to maintain high pressure, wall is thick and contains collagen fibres to give strength
What does the elastic tissue in the artery wall do?
Allows wall to stretch and recoil when heart pumps, felt as pulse where arteries are near skin, recoil keeps high pressure while heart relaxes
What does the smooth muscle in the artery wall do?
can contract and constrict the artery, constriction narrows lumen -in arterioles this is used to limit blood flow to certain tissues to redirect to other tissues
How is the endothelium arranged in the arteries?
folded and can unfold when artery stretches
In a cross section of a vein, what are the different layers from inside to out?
lumen (larger than in artery), endothelium, elastic fibres, smooth muscle, collagen fibres
Where do veins carry blood? What pressure is the blood at?
Blood back to the heart, low pressure so walls don’t need to be thick
How does the lumen, collagen layers, smooth muscle and elastic tissue in veins compare to that of arteries?
Lumen relatively large and layers of wall are thinner, no need to stretch and recoil
What is the main feature of the veins?
contain valves to prevent blood flowing in opposite direction, as walls are thin, the vein can be flattened by action of surrounding skeletal muscle, pressure is applied to blood focing blood to move along in vale direction
What do capillaries consist of?
Lumen and endothelium, walls are very thin (single layer of flattened endothelial cells)
What is the purpose of capillaries?
Allow exchange of material between the blood and cells of tissue via the tissue fluid
How narrow is the lumen of the capillary?
diameter same as RBC (7um), ensures RBCs squeezed as pass along capillary helps to give up their O2, reduces diffusion path
What dissolved substances does blood plasma contain?
O2, CO2, salts, glucose, fatty and amino acids, hormones and plasma proteins
What cells travel in the blood?
RBCs: erythrocytes, various WBCs: leucocytes and fragments: platelets
What is tissue fluid made up of?
some phagocytic WBCs, some hormones and proteins secreted by body cells, no fats
What is the role of the tissues fluid?
transport O2 and nutrients from the blood to the cells and carry CO2 and other wastes back to the blood
What happens to an artery when it reaches the tissues?
Branches into smaller arterioles, then into network of capillaries which eventually link up with venules to carry blood back to veins
What is the pressure like at the arterial end of a capillary?
High pressure die to contraction of heart muscle, hydrostatic pressure, tend to push blood fluid out of capillaries via tiny gaps in the wall
What does the fluid that leaves the blood in the capillaries consist of?
plasma with dissolved nutrients and O2
RBCs, plasma proteins, platelets and most WBCs remain in blood (all too large)
What is the fluid that leaves the capillary known as? What does this fluid do?
Tissue fluid, surrounds body cells so exchange of gases and nutrients can occur across membranes (diffusion and facilitated diffusion)
How does tissue fluid return to the blood?
tissue fluid has some hydrostatic pressure which tends to push the fluid back into the capillaries
Why does water from the tissue fluid tend to move back into the blood?
blood and tissue fluid contain solutes so negative water potential but water potential of tissue fluid is less negative than blood so water back into blood by osmosis
What is the pressure like at the venous end of the capillary?
Blood has lost hydrostatic pressure, combined effect of tissue fluid pressure and osmotic force of plasma proteins moves fluid back into capillary carrying with it dissolved waste substances (CO2)
What happens to tissue fluid which doesn’t return to the blood?
Some drained to lymphatic system, number of vessels/tubes similar to capillaries, start in tissues and drain excess fluid in larger vessels which rejoin blood system in chest
What does the lymph fluid contain?
lymphocytes, some proteins, more fats than in blood (absorbed from intestines)
Where are lymphocytes produced?
Lymph nodes, swellings at intervals along lymphatic system, filter bacteria and foreign material from lymph fluid
What do lymphocytes do?
engulf and destroy the foreign material and bacteria, part of immune system protecting body from infection
How much glucose, amino acids, O2 and CO2 does the blood, tissue fluid and lymph have?
Blood: 80-120 mg/100cm3, more, more, little
TF: less, less, less, more
Lymph: less, less, less, more
