Unit 4a - Circulation Basics Flashcards
Functions of the Circulatory system (5)
-diffusion, convection, transportation, transportation of heat, production of heat
3 basic components of the cir sys.
- circulatory fluid 2. pump 3. Vascular system
Characteristics of an open system
- incomplete system of vessels - most invertebrates -low blood flow and BP -slow return of blood to the heart
Characteristics of a closed system
- enclosded system of vessels -vertebrates, some inverts -higher blood flow and BP -blood/tissue exchange across capillary walls
Advantages of a closed system
- control velocity and distribution of blood -increase in metabolic rate and body mass -enable evolution of glomerula kidney
Undivided vs. divided blood (pros of divided)
- undivided= no separation -divided= complete or partial separation pros of divided= increased BP to body, increased metablolic rate and body mass
Evolutionary trend to become O2 breathers
- increase in o2 uptake -increased size- energy goes up - need separation of blood as well as an effecient blood transportation system -increase in BP and flow
3 types of vessels
arteries, veins and capillaries
what is the structure of the vessels
- all have an endothelial lining -arteries and veins have connective tissue (elastic and collagenous fibres) and smooth muscles
how does cross-sectional area affect velocity
-small cross section-= highest velocity = arteries, aorta
how does the large area of the capillaries influence the ability and speed of O2 delivery
- large area, velocity is low- spends a lot of time going through, allows lots of diffusion to occur
Tunica media and tuica adrentitia
tunica media- muscle layer around the endothelium tunica adrentitia= outer fibrous layer
How does the tunica media differ between large and medium arteries
large= elastic (needs to expand) medium= muscular
Compliance
-the elasticity of the aorta walls allows for dampening of the oscillation of the heart to allow for continuous blood flow
Arteries- Characteristics
- large= low resistance, low pressure drop -pressure is determined by the volume of blood and the wall properties - in charge of maintaining blood flow - thick muscular wals to withstand high pressure -PRESSURE RESERVOIR
What two factors can cause pressure in the arteries to increase and decrease respectively?
increase in cardiac output= increase in pressure increased flow into capillaries= decrease in pressure
Veins- Characteristics
- large diameter, low pressure, \ -VOLUME RESERVOIR (50% of blood) -smooth muscles, sympathetitc adrenegetic fibres —-these are less elastic- will tear if pressure is hight -venous blood flow is affected by muscle contractions and valves (expansion of the chest helps move venous blood to the heart)
What happens when blood volume is lost from the venous system ie. giving blood
- vasoconstriction reduces the volume, so pressure stays constant as well as flow rate
What happens when blood pools in the veins
-venous return drops, cardiac output dops, arterial pressure drops, less blood to the brain= faint
Capillaries Characteristics
- approx 1 mm long 3-10um in diameter -endothelial cells with a basement membrane -extensive network an high surface area
What are the functions of the capillaries
- gas, nutrient and waste exchange -fluid exchange and balance
how does gas exchange and waste exchange occur in the capillaries
- down concentration gradients or partial pressure -gradient is determined by cellular metabolism
how does fluid exchange occur in the capillaries
- diffusion is porportional to permeability -lipid soluble substances pass through the membrane (o2 co2) -others (ions, water, glucose) pass through water-filled channels in the capillary walls (slower)
What are the three types of permeable capillaries
-continuous, fenestrated, sinusoidal
Continuous Capillaries
-muscles, NS, connnective tissue, lungs -least permeable -intercellular clefts with a basement membrane -H20, small ions and molecules can pass through
Fenestrated Capillaries
-renal glomerulus (kidney) -intermediate permeability -allow passage of everything except large proteins and RBCs
Sinusoidal Capillaries
-liver -highly permeable -intercellular gaps -allow passage of proteins
Lymphatic circulation
-contains WBCs but no RBCs -exchange between plasma and interstitail fluid driven by hydrostatic and osmotic pressure gradients -overal filtration pressure> absorption pressure- net fluid loss, lymphatic system returns 15% of the fluid
Hydrostatic pressure and colloid osmotic pressure in the lymphatic system and difference between atrial and venous side
-hydrostatic (net filtration force)- fluid leaves the capillaries -colloid osmotic pressure (net absorption force) - fluid enters the capillary -atrial = net filtration -venous = net absorption
Function of the lymphatic circulation (3)
- returns fluid and plasma proteins to primary circulation -absorption of fat and fat-soluable nutrients from lacteal in gut -immune system repository
structure of the Lymphatic system
-parallels the venous system -lymph capillaries have highly permeable walls -lymph capillaries- lymph trunks- empty into veins near the heart
Fluid movement in the Lymphatic system
-moves via diffustion -valves control the movement- only away from lymphatic capillaries -also driven by capillary contraction and contraction of surronding muscles and the gut
diseases of the lymphatic system (2)
-both of these cause edema- increase in tissue volume -filariasis (elephantitus) -kwashiorkor (protein starvation)
how do the lymphatic systems of fish, amphibians, reptiles and birds differ from mammals
fish- absent -amphibians- lymph heart and large lymph storage -reptiles- lymph heats -bird embryos - pevic lymph hearts
Systole
contraction
diastole
Relaxation
Action potential
electrical signal to contract triggered by depolarization
Pacemaker cells
-initiate electrical activity -cells with fastest intrinsic rate of activity
where are the pacemaker cells in vertebrates
sinous venosus or sinoatrial node
what are the two types of pacemaker cells
-neurogenic and myogenic
What are do P, Q, R, S and T stand for on an ECG
P- atrial depolarization
QRS- ventricular depolarization
T- ventricular repolarization
What does parasympathetic innervation (vagus nerve) do
lowers heart rate
involves achetocholine which increases K+ and reduces Ca2+
NEGATIVE CHRONOTROPIC EFFECT BITCHES
What is a negative chronotropic effect
an effect that lowers heart rate
Sympathetic innervation and catecholamines do what?
positive chronotropic, inotropic and dromotropic effect
norepinepherin and epinepherin
imcrease rate of myocardial contractions
increasce force of myocardial contraction
increase the speed of conduction of the wave of excitation
