Ch15 Flashcards
Why do large organisms need transport system and 2 factors
Surface area to volume ratio decreases so organisms cannot depend on exchange through body surface
- how active organism is
- SA:V ratio
Features of transport system
Suitable medium to carry materials: blood as based on water and can be moved around easily and dissolve substances readily
Closed system of tubular vessels to form branching network to distribute transport medium to all of organism
Mechanism with pressure difference to move transport medium within vessels
Mechanism to maintain mass flow movement in one direction like valves
Mechanism of moving transport medium in animals and plants
Animals : muscular contraction
Plants : evaporation of water
Why mammals have Double circulatory system
When blood passes through lungs pressure decreases meaning circulation very slow this wouldn’t allow substances to be delivered readily
Needed as mammals have high body temperature so higher metabolism
Liver vessels
Away : hepatic vein
To : hepatic artery
Stomach and intestine vessels
Away to liver : hepatic portal vein
To : arteries
Kidneys vessels
Away : renal vein
To : renal artery
Structure of blood vessels
Tough outer layer : resists pressure changes
Muscle layer : contract and control blood flow
Elastic layer helps maintain blood pressure by stretching and recoiling
Endothelium: smooth prevents friction and thin to allow diffusion
Lumen which is the central cavity of blood vessel through which blood flows
Artery structure
Transports blood under high pressure from heart to tissue
Muscle layer thick compared to veins to control volume of blood passing
Elastic layer thicker than veins to maintain high blood pressure by stretch and recoil
Thick walls to resist vessel bursting under high pressure
Arterioles
Carry blood Under lower pressure than arteries to capillaries
Thicker muscle layer than arteries to allow contraction of lumen to restrict the flow of blood and movement into capillaries
Relatively large lumen as vessel wall thinner
Elastic layer thinner as blood pressure lower
Veins
Carry blood under low pressure from tissue to heart
Muscle layer thin as constriction cannot control flow of blood to tissues
Elastic layer thin as pressure too low to create a stretch and recoil
Overall thickness of wall small as low pressure
Valves ensure blood doesn’t flow backwards
Capillaries
Exchange metabolic materials between blood and cells
Slow flow to alow more time for exchange of materials
Only endothelium walls = thin so short diffusion distance = rapid diffusion of materials between blood and cells
Highly branched = large SA for diffusion
Narrow diameter = permeate tissues so no cell is far from capillary
Narrow lumen = RBC squeezed flat against side of capillary reducing diffusion distances
Space between endothelial cells : allow WBCs to escape and deal with infections within tissues
Tissue fluid
Contains glucose amino acids fatty acids salt and oxygen
Supplies all these substances to tissues and receives CO2 and other waste products
Made of blood plasma
Formation of tissue fluid HP
HYDROSTATIC PRESSURE:
HP much higher at arteriole end so fluid forced out at arteriole end of capillary
only small molecules move out so proteins left in blood
some HP from tissue fluid forces fluids back into capillaries but net movement is out
Tissue fluid at venous end HP
loss of tissue fluid from capillaries reduces HP in them
HP at venous is lower than tissue fluid outside
tissue fluid forced back into capillaries
Lymph
Tissue fluid thats not returned to capillaries goes into the lymphatic system
Dead ends so pressure on them can only produce movement in one direction
Gradually merge into larger vessels
Content moved by :
Hydrostatic pressure of tissue fluid that left capillaries
Contraction of body muscles squeeze the lymph vessels
Valves ensure fluid moves away from tissue and to heart
Relaxation (diastole)
atria fills = rise in pressure
Atrioventricular valves open
Blood passes into ventricle
Muscular walls of atria and ventricles are relaxed = reduction in pressure within ventricles
Lower pressure in aorta and pulmonary artery
Semilunar valves in aorta & PA close ‘dub’
Contraction of atria (artial systole)
Muscle of atrial wall contracts = blood forced into ventricles
Blood only pushed short distances so thin muscular walls & remain relaxed
Contraction of ventricles (ventricular systole)
Short delay to allow ventricles to fill up with blood
Walls contract simultaneously = increased blood pressure within ventricles
Closing if AV valves = preventing back flow of blood into atria ‘lub’
Rise in pressure within ventricles = opening of semilunar valves & pushes blood into PA and Aorta
Atrioventricular valves
Between left/right atrium and left/right ventricle
Prevent back flow of blood into atria
Ensures blood moves out to aorta and PA
When contracts the ventricular pressure exceeds atrial pressure
Semilunar valves
In aorta and PA
Prevent back flow of blood into ventricles
Recoil action of elastic walls creates greater pressure in vessels than ventricles
Pocket valves
Ensure that when veins are squeezed blood flows back to heart rather than away
Structure of valves
Made of flaps of tough but flexible fibrous tissue
Cusp shaped
Pressure greater on convex side = move apart to let blood pass through
Pressure greater on concave side = blood collects within bowl of cusps to push then tgt and prevent blood from passing through
Tendons
Prevent AV valves from becoming inverted due to high pressure
Cardiac output
Volume of blood lumped by one ventricle in one minute
Heart rate x stroke volume (volume of blood pumped at each beat)
Cardiac cycle
Myogenic so contraction initiated within the muscle itself
SAN initiates stimulus for contraction “pacemaker”
Events of cardiac cycle
Wave of electrical activity spreads from SAN across both atria causing them to contract
Layer of nonconductive tissue prevents waves from crossing to ventricles
Wave of electrical activity passes through AVN which lies between atria
AVN after short delay to fill ventricles with blood conveys wave of electricity between ventricles by fibers called bundle of his
Bundle of his conduct the wave through AV septum to base of ventricles
Wave of electrical activity released from bundle of his causing ventricles to contract at same time
Why is the electrical wave not allowed to pass through ventricle
Ensures Proper Timing of Contractions
heart chambers might contract simultaneously, reducing the efficiency of blood pumping.
The nonconductive layer forces impulses to travel through the atrioventricular (AV) node, which introduces a slight delay, allowing the ventricles to fill with blood before they contract.
arteriole end (osmotic)
net loss of water due to HP
proteins left in capillaries
water moves down WP gradient from tissue into capillaries (ultrafiltration)
Venous end osmotic
WP of blood plasma is lower than tissue fluid
Net movement is from tissue to blood plasma by osmosis
Lymph
Excess tissue fluid collected to avoid swelling
Drained into the lymphatic system
Moved by : HP of tissue fluid that left capillaries
Contraction of body muscles that squeeze lymph vessels
Adaptations of Lymph
Like tissue fluid but moves lipids and lymphocytes
Valves to prevent backfolow
Lymph nodes = site of lymphocytes
Help filter out and and destroy any foreign material
Locate at sites that can intercept pathogens before entering circulatory system
CHD
Build up of fatty deposits —> lead to myocardial infarction (heart attack)
Atheroma
Endothelium damaged due to high pressure
WBCs and platelets arrive to repair damage
Clump with lipids from blood = fatty deposits
Build ur hardens and firm atheroma
Decreases diameter of lumen = less blood flow
Thrombosis
Atheroma breaks through endothelium = disruption of blood flow
Platelets accumulate at site of damage
Blood clots form
Can complete block off blood vessels
Prevents blood supply to tissues behind
Tissues die due to lack of oxygen and nutrients
Aneurysm
Atheromas that lead to thrombus weaken artery wall
Weakened points swell to form a ballon-like filled with blood (aneurysm)
Frequently burst leading to hemorrhage
Resulting in loss of blood supply to surrounding tissue
Myocardial infarction
Blockage in coronary arteries
Leads to reduced supply of oxygen to heart muscle
Nearer to CA = heart stops completely
Further along CA = milder symptoms
Risk factors
Smoking
High blood pressure
Cholesterol
Diet
Smoking
CO : binds irreversibly and easily with HB in RBC to form carboxyhemoglobin
Reduces oxygen carrying capacity of RBC
Heart has to work harder
Nicotine : stimulates production of adrenaline
Increases heart rate = more pressure and strain on heart
High blood pressure
Increases formation of aneurysm and bursting
Walls of arteries may become hardened and thickened to resist higher blood pressure = restricted blood flow
Cholesterol
Can be found within membrane
High density lipoproteins HDL : removes cholesterol from tissues to liver
Low density lipoprotein LDL : transport cholesterol from liver to tissues
Diet
High levels of salt : increased blood pressure
High levels of saturated fat : increase LDL levels = increased cholesterol conc
