BSC 3096 Learning Objectives 14-20

Functions of the cardiovascular system

1. Transport of materials entering/leaving the body, or needing to go to other parts of the body for processing 

2. Cell to cell communication

3. Immune responses

4. Thermoregulation

Transport of materials entering/leaving the body

moving blood

transports oxygen from the lungs to the body's cells and carries carbon dioxide from the cells back to the lungs for exhalation.

Cell to cell communication (hormones)

Hormones produced by endocrine glands are transported through the blood to target organs and tissues, facilitating communication and regulation of various physiological processes.

Thermoregulation

the process by which the human body maintains its core internal temperature.

Aorta

Blood is pumped from the left ventricle

the largest artery in the body

Arteries

Always carry blood away from heart

branch off into Arterioles

Capillaries

Arterioles lead to this

exchange of oxygen, nutrients, and waste products occurs between blood and tissues.

Between arteries and veins; type of blood vessel

Veins

Carry blood towards the heart

Venae Cavae

Blood from the upper body flows into the superior vena cava, while blood from the lower body flows into the inferior vena cava.

Receives blood from systemic veins sends blood to right atrium

Right Atrium and Ventricle

Blood flows from the right atrium to the right ventricle, which pumps it to the lungs via the pulmonary arteries for oxygenation.

Pulmonary Veins:

Oxygenated blood returns from the lungs to the left atrium through the pulmonary veins.

Receives blood from veins of lungs sends blood to left atrium

Left Atrium and Ventricle:

Blood flows from the left atrium to the left ventricle, completing the circuit as it is pumped back into the aorta.

CVP

central venous pressure

Hydrostatic pressure:

the pressure exerted on the walls of the container by the fluid within the container

Poisecille’s law shows the relationship of the factors defining ___ in a blood vessel

resistance

vasoconstriction

decrease in flow

pericardium

a strong, protective sac around the heart.

Protecting the heart, Lubricating with fluid, Anchoring the heart in place

Myogenic

electrical potential generated by muscle itself

neurogenic

electrical potential generated by nervous system

Heart wall has 3 layers

1) epicardium

2) endocardium

3) myocardium

epicardium

outer layer of the heart

visceral pericardium

endocardium

inner layer of the heart

myocardium

middle layer of the heart

cardiac myocytes

Flow is ___ proportional to the pressure gradient and ___ proportional to resistance.

directly; inversely

At a constant flow rate, velocity ___ in narrower vessels and ___ in wider vessels.

increases; decreases

Apex:

The pointed end of the heart, which angles down to the left side of the body and rests on the diaphragm.

Base:

The broader end of the heart, located just behind the sternum.

Pulmonary Trunk (Artery):

Carries deoxygenated blood from the right ventricle to the lungs.

Atria:

The upper chambers (right and left atria) receive blood returning to the heart.

Ventricles:

The lower chambers (right and left ventricles) pump blood out of the heart.

Valves

Ensure one-way blood flow

Atrioventricular (AV) Valves:

Between atria and ventricles (tricuspid valve on the right, bicuspid/mitral valve on the left).

Semilunar Valves:

At the exits of the ventricles (pulmonary valve on the right, aortic valve on the left).

contractile cells

contract/ generate a force

connected by intercalated disks

Na entry

Autorhythmic Cells

Depolarize at a specific rate, unsteady resting membrane potential (+) evenly distributed

Also called SA/AV node, do not have a resting membrane potential

initiate and propagate electrical signals

Ca influx

Sinoatrial (SA) Node:

electrical signals begins here in the right atrium.

natural pacemaker, generate action potentials that set the pace for the heartbeat.

Atrioventricular (AV) Node

The AV node delays the signal slightly, allowing the atria to complete their contraction before the ventricles begin to contract.

located near the floor of the right atrium, is the only pathway for the signal to reach the ventricles.

AV Bundle and Bundle Branches:

From the AV node, the signal moves through the AV bundle (bundle of His), then splits into left and right branches, traveling down the heart’s center toward its tip.

Purkinje Fibers:

spread throughout the ventricles.

transmit the signal very rapidly, ensure that the ventricles contract almost simultaneously.

P Wave

Atrial depolarization

P-R Segment

Portions that don’t include wave forms

QRS Complex

Ventricular depolarization

T Wave

Ventricular repolarization

T-P Segment

The heart is electrically quiet

the heart takes a long time to __ not a lot to contract

relax

Stroke volume

EDV-ESV

Diastole

State of relaxation

Isovolumetric Contraction

The ventricles begin to contract, increasing pressure without changing volume because all valves are closed.

No blood flow occurs during this phase

Systole

State of contraction

Cardiac Output (CO)

amount of blood leaving the heart per minute

Heart Rate (HR):

The number of heartbeats per minute.

Stroke Volume (SV):

The amount of blood leaving the heart with each beat/stoke

Heart is under tonic control by the __

ANS

PNS affects only

heart rate

negative chronotropic effect

slows down heart

SNS affects both

heart rate and contractility

positive chronotropic and inotropic effects

increases heart rate

Sympathetic Division

Increases heart rate

Sympathetic neurons release norepinephrine, which binds to beta-adrenergic receptors on the heart's pacemaker cells (SA node). This binding increases the rate of depolarization, leading to a faster heart rate.

Increases Na and Ca

Parasympathetic Division

Decreases heart rate. Does Not affect myocardium only slows it down

Parasympathetic neurons release acetylcholine, which binds to muscarinic receptors on the SA node. This binding increases potassium permeability and decreases calcium permeability, slowing the rate of depolarization and thus reducing heart rate.

EDV is determined by venous return, which is affected by:

Skeletal Muscle Pump

Respiratory Pump

Sympathetic Innervation

Skeletal Muscle Pump

Contractions of skeletal muscles compress veins, pushing blood toward the heart

cant act w/o venous valves

Respiratory Pump

During inspiration, pressure changes in the thorax and abdomen enhance venous return.

Sympathetic Innervation

Constriction of veins by sympathetic activity squeezes more blood into the heart.

Preload

Degree of myocardial stretch prior to contraction via EDV

Afterload

the resistance the ventricle must overcome to eject blood. Higher afterload decreases stroke volume as the heart must work harder to push blood out. ex) hypertension is an increase in afterload

Frank starling law

blood that returns to the heart will be pumped out of the heart

Parasympathetic innervation at the vagus nerve ___ the rate of depolarization in autorhythmic cells

decreases

Sympathetic innervation and epinephrine ___ the rate of depolarization in autorhythmic cells which increases heart rate

increases

Epinephrine and norepinephrine bind to ___ that activate ___ second messenger systems resulting in phosphorylation of voltage gated Ca channels and phospholamban

beta 1 receptors

cAMP

Phospholamban

a regulatory protein that plays a crucial role in the heart's ability to contract and relax

flow is directly proportional to

delta P/R

R=

8Ln/pi r^4

Cardiac output=

heart rate x stroke volume

pulse pressure=

systolic pressure- diastolic pressure

MAP=

(SBP+DBP+DBP)/3

need pressure to be low before putting in capillaries bc capillaries are

fragile

Precapillary sphincters are present only in

splanchnic circulation

Venous valves work like which of the heart valves?

semilunar valve

In which veins will you NOT find valves?

venae cavae, pulmonary veins, hepatic portal vein, and cerebral veins

Hepatic Portal Vein:

This vein carries nutrient-rich blood from the digestive organs to the liver. It lacks valves to allow a steady flow of blood to the liver.

Cerebral Veins & Dural Venous Sinuses:

The veins of the brain drain into sinuses that rely on gravity and pressure differences rather than valves to move blood.

TPR=

total peripheral resistance

More blood in arteries=

more blood pressure

How Blood Pressure Works:

Heart Contraction – The left ventricle pumps blood into the aorta, creating high pressure.

Elastic Recoil – The aorta and arteries expand and then recoil to keep blood moving.

Pressure Changes in Circulation:

Arteries – Highest pressure to push blood through the body.

Arterioles – Pressure drops as these small vessels control blood flow.

Capillaries – Lower pressure allows nutrient and gas exchange.

Veins – Lowest pressure; valves help blood return to the heart.

Pressure Gradient:

Blood flows from areas of higher pressure (arteries) to lower pressure (veins) due to the pressure gradient.

The heart creates high pressure when it ___, pushing blood into the arteries. This pressure ___ as blood moves through the circulatory system due to friction with vessel walls.

contracts; decreases

The pressure created by ventricular contraction is the ____ for blood flow.

driving force

Sphygmomanometry:

used to estimate arterial blood pressure, typically in the radial artery of the arm.

Describe how blood pressure is estimated using sphygmomanometry.

Inflate the cuff to stop blood flow.

Slowly release the pressure.

Listen for thumping sounds (Korotkoff sounds) as blood starts flowing again.

When cardiac output increases, more blood is pumped into the arteries, raising the blood volume and thus increasing the

mean arterial pressure

When resistance increases, blood flow slows, causing it to build up in the arteries and

raising blood pressure

hypertension

chronically elevated blood pressure.

hypotension

abnormally low blood pressure

Which is worse: hypertension or hypotension?

Hypotension because blood can't go to organs and tissues start to die

Why is blood pressure highly regulated in the body?

Ensuring Adequate Blood Flow

Maintaining Continuous Blood Flow

Regulating Blood Distribution

Preventing Hypotension and Shock

Integration with Other Systems

Maintaining Continuous Blood Flow

Arteries store pressure from the heart and release it through recoil to keep blood flowing steadily

Regulating Blood Distribution

Arterioles control blood flow by tightening or widening, directing more blood to active tissues and less to inactive ones

Integration with Other Systems

The kidneys help regulate blood pressure by controlling fluid balance. Hormones from the heart and kidneys work together to keep stability. The heart and lungs also work together to meet oxygen needs

Radius is the most important factor determining resistance to

blood flow