Chapter 32 Circulation Flashcards
What does a circulatory System consist of?
Muscular pump (heart)
Fluid (blood)
Series of conduits (blood vessels)
Do Mammals and birds or lizards and frogs require more oxyge
mammals and birds - this contributes to a higher blood flow and blood pressure
How is O2 brought to cellsin insects
Brought to cells in air via tracheal system (instead of in fluid)
What is a closed circulatory system and what is its benefit
blood always remains in the vessels
can support higher level of metabilic activity
What comprises the microcirculation
arterioles, capillaries and venules
Describe the anatomy of capillaries
All are lined with simple epithelium (Vascular endothelium)
Capillaries ONLY have vascular endothelium 1 um thick
What occurs in the capillaries
primary site of release of O2, nutrient molecules and hormones and uptake of CO2 and other waste products
What process controls arteriole diameter and what is the significance
Vasomotor control - autonomic process
Controlls rate of bloodflow through capillaries
What are some cases where arterioles may be dilated
Dilated near skin to remove metabolic heat, in muscles to ncrease blood flow and O2 supply during exercise and in penis to facilitate erection
What is an open circulatory system
Blood exits vessels as it flows throught he body - no distinction between blood and interstitial fluid (haemolymph)
In arthropods and most mollusks
Describe the open circulatory system of crayfish
Heart -> arteries that carry blood to major parts of body -> vessels end and blood moves through sinuses and lacunae to ventral body spaces along bases of walking legs where gills arise -> sucking forces developed by heart pull blood through gills and back to heart
What is the difference between systemic circuit and breathing-organ circuit
Systemic - goes to systemic tissue - O2 released and CO2 taken up
Breathing-organ circuit - Adds O2 to blood and takes up CO2
How is the circulatory system of fish different to mammals and birds?
Fish have a series arrangement - (2 chamber heart) blood pumps from heart once to breathing organs then rest of body
Mammals and birds hearts (4 chambers) divided in two halves and blood goes through twice, once deoxygented, once oxygenated
How are amphibian and reptile hearts unique and what is the advantage of this?
Only have 1 ventricle, 1 atria. Blood still kept separate (not completely - some mixing)
Advantage is they can stop circulating blood to lungs when underwater
What is general resting cardiac output
5L/min
What is blood pressure
Extent to which pressure in blood exceed environmental pressure of the animal
What initiates the heartbeat
Pacemaker cells inthe sinoatrial node (R atria wall)
How does the autonomic nervous system affect the heartbeat
Heart beats on its own
ANS influences SA node - increase/decrease HR- and mycardial cells - increase or decrease contraction speed and force
ANS releases epinepherine that affects pacemaker cells in SA node by increasing repolarization rate to increase contraction rate
What do ECGs do?
register voltage difference at different times
Large APs in hart cause electrical current to flow outward to all parts of the body
What is different about crustacean hearts?
require nerve stimulation to beat
- Cell in ganglion acts as pacemaker cell and nerves relay impulses to all heart cells to contract at the same time
Open circulation - heart is suspeded in fluid filled cavity and blood reenters heart via slits called ostia when heart relaxes
Why is the anatomy of arteries different to veins
Arteries need to withstand high pressure
Thick walls of elastic fibres and smooth muscle
Stretching and relaxing dampens pressure surges and maintains pressure between heartbeets
How does blood vessel arrangement aid in heat conservation?
Arteries and veis are very close together - heat from arteries diffuses into veins, transporting heat back to corre
Countercurrent heat exchange
How do capillaries absorb water?
Osmotic pressure due to dissolve proteins excedes blood pressure in capillaries allowing osmosis into vessels
What is the role of the lymphatic system?
return interstitial fluid to the blood - empty into veins in neck
