BIOS 3430 Exam 3

open circulatory system

Hemolymph or fluid is pumped via a dorsal at low pressure. (insects and mollusks)

Closed circulatory system

Fluid is pumped through vessels and is not free floating. Extracellular fluid is kept separate and a heart is used to maintain high pressure.

Fish mechanisms of closed circulatory systems

Gills have lots of resistance, which decreases pressure. Flow is lower in fish because they're ectotherms.

Why do ectotherms have lower flow?

They have less metabolic demand

How many loops are in mammalian closed systems?

2, pulmonary and systemic loops

Properties of pulmonary loop

moves blood from the right ventricle to the lungs, lower pressure. RIGHT

Properties of systemic loop

moves blood from the left ventricle to the aorta and the rest of the body. LEFT

Relative sizes of the left and right ventricles

The left ventricle seems bigger because of myocardium and increased pressure generation.

Process of blood pumping

Blood leaves LV and enters systemic aorta. Pumps to body, inferior vena cava helps return. Enters the right atrium and then the right ventricle . Finally goes to lungs for oxygenation and then to the left ventricle.

systolic pressure

highest point of pressure on arterial walls when the ventricles contract (lub)

diatonic pressure

lowest pressure, ventricle relax (dub)

Differences in cardiac output of endotherms and ectotherms

Endotherms have higher cardiac output, so they have a larger systolic-diastolic difference.

Hydrostatic pressure

force exerted by a fluid against the container/membrane wall.

systolic/diastolic patterns

arterials dilate or constrict greatly affect pulse pressure. Average pressure declines as you move away from heart.

Mean arterial pressure (MAP)

1/3 of average pulse, indicates average pulse over time in entire system. Over the time of all blood pressure, only 1/3 of it is spent in ventricular ejection.

Equation for mean arterial pressure

MAP= Pdiastolic +1/3(PSystolic-Pdiastolic)

Anatomy of arteries

Outer coating, medial coating, inner coating

Outer coating

Fibrous tunic (Tunica adventicia)

Medial coating

Thick elastic (Tunica media)

Inner coating

Endothelial cells and elastic fibers (tunic intima)

Causes of aneurysm

Arterial walls are not thickness

Properties of veins

Not built for high pressure, contain one way valves that prevent back flow.

Consequences of vein backflow

Varicose veins

Properties of capillaries

Arterials branch to smaller vessels that allow for gas and nutrient transfer.

precapillary sphincters

regulates blood flow from arteries

post capillary venules

smallest venules that move deoxygenated blood

Greatest source of pressure in the loop, pressure resevoir

arteries, arterioles have a drop in pressure with high resistance

volume reservoir

veins

compliance

ability of a hollow organ to distend and increase volume with increasing transmural pressure or the tendency of a hollow organ to resist recoil.

Compliance comparison in vessel

Veins gave greater compliance and arteries have lower compliance. This means arteries can expand but require greater amounts of pressure.

Why do we need arterial compliance?

Non elastic aorta cannot recoil after ventricular contraction (diastole). Compliance allows constant flow of blood to the capillaries with no pauses.

Flow

Volume pumped per unit time.

Equation of flow

Frequency of heartbeats * stroke volume (volume ejected in a contraction)

Relation of flow through entire system

Flow/ min is constant through entire system loops but flow varies between different organs.

Velocity of fluids

based on cross area and flow. While flow is volume/unit time and velocity is distant/unit time.

Equation of velocity

V=Q/cm^2, where Q is flow

Relationship of cross sectional area and velocity

Smaller cross sectional area means higher velocity. Flow is equal through smaller vessels as the same volume is moving through, just at different rates.

Why do capillaries have lowest flow despite their seemingly small surface area?

Total cross sectional area matters. Capillaries have a larger total cross sectional area so they have low velocity.

Law of Bulk Flow

Flow between two points is proportional to pressure difference and resistance.

Equation for flow according to law of bulk flow

Q= DeltaP/R

Tenants of flow

As resistance increases, flow decreases. Goal of altering resistance is to alter flow, not pressure. Pressure stays relatively constant. Flow can be applied to vessels or whole systems.

Methods of increasing resistance

Vasoconstriction, increasing tube length, higher viscosity.

Equation for cardiac output

mean blood pressure (MAP)/ total peripheral resistance (TPR)

Calculate resistance in vessels

R=8nl/pir^4

What is n?

viscosity in poise

Factors affecting resistance

Length doesn't change often, but radius and viscosity do. Radius (dilation/constriction) have the greatest effects.

Poiseulle's Law

Integrates flow, pressure, resistance, radius, and length.

Equation for Poiseulle's Law

DeltaPpir^4/8Ln

Parallel and series circuits in vascular circuits

The heart and lungs are in series, the vascular beds are in parallel with each other.

Types of capillary

continuous, fenestrated, sinusoidal

continuous capillaries

Attached basement membrane

Fenestrated capillaries

larger pores in the basement membrane for tiny spaces of permeability

Sinusoidal capillaries

Large pores occur in the basement that allow for heavy molecule movement.

Factors affecting diffusion in capillaries

Membrane permeability, solute concentration, membrane thickness

Fick's Law of Diffusion

F= D *(AdeltaC/x)

What is D? What is A? What is Delta C? What is x?

diffusion coefficient, area, change in solute concentration, thickness of membrane.

Bulk flow and capillary fluid movement

Hydrostatic pressure pushes fluid out to extra capillary space, osmotic pressure uses albumin to pull fluid back in.

General trend of fluid movement

More fluid tends to get pushed out then gets pushed in.

Four starling forces

capillary pressure, plasma colloid osmotic pressure, interstitial fluid pressure, interstitial fluid colloid osmotic pressure

Equation of flux across wall

J= [K(Pcap-Pint]-[sigma(picap-piint)]

Pcap and Pint

Capillary blood (hydraulic pressure) and interstitial fluid pressure

Lymphatic system

Fluid left behind in interstitial tissues don't go back to capillaries and are picked up.

Edema

Blocked lymphatics, not enough albumin (large amt of interstitial fluid), high capillary pressure.

right atrium

Receives deoxygenated blood from the body via the superior and inferior vena cava.

right ventricle

pumps deoxygenated blood to the lungs

pulmonary artery

artery carrying oxygen-poor blood from the heart to the lungs

left ventricle

pumps oxygenated blood to the body via the aorta

The valves located between the atria and ventricles are known as the ________ valves.

atrioventricular

function of atrioventricular valves

Prevent blood returning to atria during ventricular contraction

Two atrioventricular valves

tricuspid and mitral

semilunar valve function

prevent backflow into the left and right ventricles

two semilunar valves

pulmonary and aortic

Chamber order of blood flow in heart

Right atrium, right ventricle, left atrium, left ventricle

Valve order in the heart

Tricuspid, Pulmonic, Mitral, Aortic

Common causes of heart failure

High blood pressure, valve calcification, artery blockage, artery hardening.

two types of valve replacement and their differences

mechanical and bioprosthetic. Mechanical is a ball in cage model to replicate valves while bio prosthetic is a transplant bound to a frame.

Unique properties of cardiac muscle

striated muscle, uses oxidative phosphorylation for long term energy. Cells are coupled via gap junctions for ion flow, causes coupled contraction. Left and Right ventricles contract together in systole.

SA node

site of cell depolarization, sends out waves of depolarization in the right atrium. Left atrium depolarization occurs at the same time.

AV node

connects atrium and ventricles. Creates the delay between atrial and ventricular contraction. Moves blood in the right direction, allows blood to move from atria to ventricle, then ventricle to the next step.

Purkinje fibers

fibers in the ventricles that transmit impulses to the right and left ventricles, causing them to contract. ENDOCARDIUM TO EPICARDIUM TRANSITION

firing speeds in different parts of the heart

Speed of AP is faster as it moves through the ventricle, slowest in the nodes.

plateaus of cardiac action potentials

In skeletal muscle, there is a spike where summation nd tetanus can occur. In cardiac muscle there is a sustained AP where complete refraction occurs and there is no summation or tetanus.

Properties of pacemaker AP

no pleatau, unstable resting potential due to leaky NA allows for spontaneous depolarization.

ectopic pacemaker

a pacemaker other than the SA node, generates AP if node does not have a strong enough depolarization

Neurogenic vs myogenic pacemakers

In vertebrates, myogenic contracts heart. In invertebrates, the nerve cells undergo spontaneous activity to trigger heart rate.

Positive chronotropic effects vs negative

inputs that speeds up heart rate (sympathetic), inputs that slow down heart rate (parasympathetic)

Mechanisms of positive and negative chronotropy

positive due to norepinephrine or epinephrine and negative due to acetylcholine. Adrenal gland secrets norepinephrine and epinephrine while the vagus nerve slows response.

AV block

pacemaker disorder where the action potential doesn't go from AV node to Perkinje fibers

Sick sinus syndrome

SA node doesn't transmit impulse

Normal electrocardiograms

P wave associates with QRS complex (peak), if there is a large gap between them it can lead to atrial ventricular communication problems.

Steps of cardiac cycle

a complete atrial ventricular contraction consists of filling and emptying in discrete phases

mid diastole

all 4 chamber fill

atrial contraction

atria push and valves start to close between atria and ventricles

Ventricular contraction

Ventricles push due to greater pressure and the AV valve closes.

Ventricular ejection

valves open so ventricle can push blood

isometric ventricular relaxation

fibers relax in shortened phase

Pressure requirements in the ventricle

Must exceed higher Pv due to the higher MAP in aorta, so ventricle pressures are much more elevated than atrial pressure.

Stroke volume

the volume of blood pumped out by a ventricle with each heartbeat, ventricular emptying to aorta does not expel all liquid.

equation for cardiac output

CO = HR x SV

equation for SV

EDV-ESV (full-empty), changes based on activity levels and available work