BIOL 4431 Exam 3 Part 2: Cardiovascular Functions

Blood components

Plasma is made with: Blood minus cell, ~50% of whole blood;

has water which is 90% of plasma and >100 diff. solutes;

has proteins mostly from liver and ~8% of plasma weight;

has albumins which is ~60% of plasma proteins, shuttle non-polar mols, maintain blood vol. (osmotic pressure), and act as buffer (bind & release H+)

has other proteins like antibodies & clotting factors

has other substances like nutrients, gasses, wastes, & ions

Serum

Plasma - plasma proteins;

Clotted-spun blood

Platelets

Involved in clotting,

Contact damaged surface & rupture,

Release contents,

Causes additional platelet sticking,

Platelet plug formed

Erythrocytes (red blood cells)

Biconcave shape (optimizes diffusion),

Contain hemoglobin (O2 carrier)

Leukocytes (WBC): Granulocytes

Inherited immunity (non-specific),

Lobed nuclei,

Neutrophils – stain little,

Eosinophils – stain pink,

Basophils – stain blue

Leukocytes (WBC): Agranulocytes

Acquired immunity (specific),

Less lobed nuclei

Formed element production

Same hematopoietic stem cell differentiates into all,

Different elements have different pathways

Antigen

CHO residue on RBC

Antibody

Recognizes antigen as self vs. non-self

O antigen

everyone has this

A antigen

“A” blood type

B antigen

“B” blood type

O

has A & B antibodies

A

has B antibodies

B

has A antibodies

AB

has no antibodies

Rh factor (D antigen)

are additxnal antigens and most people have it

Atria (atrium)

Receiving chambers from body (systemic) + lungs (pulmonary)

Right atrium blood source

Superior and inferior vena cava (from systemic)

Coronary sinuses (from myocardium)

Left atrium blood sources

Right & left pulmonary veins

Ventricles

Discharging chambers to body (systemic) + lungs (pulmonary)

Right ventricle

Thinner vs. left

Pumps to pulmonary trunk (artery)

Left ventricles

Thicker vs. right

Pumps to aorta (artery)

Pulmonary circuit

From right heart through lungs then returns to left heart

Low pressure (~15 mmHg)

Systemic circuit

From left heart through body then returns to right heart

Higher pressure (~100 mmHg)

Pericardium

Double-walled sac around heart

Within mediastinum (medial thoracic cavity)

Protects & anchors heart

Fibrous pericardium

Dense Connective Superficial tissue layer that helps prevent overfilling

Parietal

Below fibrous with serous (watery) secretions

Visceral

Against heart and serous

Pericardial cavity

B/w visceral & parietal that contains serous fluid, allowing smooth gliding of heart

Cardiac Muscle

Myocardium; Contractile layer of heart; Spiral & circular bundles

Joined by fibrous skeleton that works as one unit (interconnected cells)

Spontaneously depolarizes

Intrinsic rhythm

Intercalated disk

Depolarizes adjacent cells

Cardiac action potential

Plateau phase due to Ca++ entry

Long (250msec)

Endocardium

Smooth endothelial sheet (squamous)

On thin connective tissue layer

Lines chambers

Continuous w/ vessels

Valves

connective tissues reinforced endocardium that prevent backflow

Atrioventricular (AV) Right valve

Tricuspid

Atrioventricular (AV) Left valve

bicuspid (mitral)

Semilunar (SL) Valves

Aortic & pulmonary

Ventricular exits

Chordae tendineae

Anchor valve cusps (flaps) to papillary muscles

Papillary muscles

Small muscles located in the ventricle walls that help prevent the backflow of blood by keeping the atrioventricular valves closed during ventricular contraction.

Stenosis

Incomplete opening

Insufficiency

Incomplete closing

Prolapse

Valve bulges backward

Arteries

Branches from aorta and supply cardiac muscle

Veins

Roughly follow coronary artery paths, which join to form sinuses and empty into R. atrium

Systole

Ventricular contraction

AV valves close & SL valves open

Diastole

Ventricular relaxation

SL valves shut while AV valves open

“Lub”

Vents contract and AVvs close

“Dub”

Vents relax

SLvs close

Blood pressure measurement

Pressure in large arteries

Fluctuates w/ systole & diastole

Blood pressure measurement procedure

Occlude circulation w/ cuff then gradually release pressure

First sound

Systolic pressure (turbulent flow)

Last sound

Diastolic pressure

No sound

laminar flow

Sinoatrial (SA) node

Fastest intrinsic rhythm (pacemakers)

Conduction system

1. Sinoatrial (SA) node

2. Atrial depolarization

3. Atrioventricular (AV) node

4. AV bundle (of His)

5. Rt. & left bundle branches

6. Purkinje fibers

7. Cardiac muscle

Electrocardiogram (EKG)

Electrical picture of heart
Measured w/ skin electrodes

P wave

Atrial depolarization

QRS complex

ventricular depolarization

T wave

ventricular repolarization

Cardiac pressure cycle: Isovolumetric contraction

Pressure up and AVvs snap shut (lub)

Cardiac pressure cycle: Ventricular pressure exceeds aortic

SL valves open

Cardiac pressure cycle: Ventricles empty

Pressure go up then down; SLvs shut

Cardiac pressure cycle: Isovolumetric relaxation

All valves shut

Cardiac pressure cycle: Atrial exceeds
ventricular pressure

A-V valves open and ventricles fill

Cardiac pressure cycle: Atrial contraction

Ventricles topped off

Cardiac output (CO, ml/min) = Heart rate( HR, beats/min) * Stroke vol (SV, ml/beat)

Heart rate( HR, beats/min) * Stroke vol (SV, ml/beat)

Heart rate control

Rate of spontaneous depolarization and Chronotropic (timing) effect

Sympathetic do what?

inc. HR

inc contractility which inc Ca++ (ionotropic effect) and inc conduction speed through heart

Parasympathetics

dec. HR

End diastolic volume (EDV)

From venous return, preload, and if inc. then SV inc.

Peripheral resistance (PR)

Resistance of arterial vessels, afterload, if inc. then SV dec.

Contractility

Strength of contraction

Frank-Starling law?

if ventricle strength inc → contraction force → then SV inc (graph shifts left to resemble inc)

enhanced by Sympathetic

Ejection fraction

% EDV pumped out of heart (~ 60%)

Preload (EDV) factors

Venous smooth muscle constriction and Skeletal muscle pump

inc. intrathoracic pressure → inc. return

inc. blood volume → inc. return

Cardiac center is where?

In medulla

Cardioacceleratory center is what?

To SA & AV nodes

Sympathetic fibers projected (+ cardiac muscle)

Cardioinhibitory center is what?

Parasympathetic fibers projected

To SA & AV nodes

Arteries - Elastic (conducting)

Largest diameter

mainly elastic tissue

inc pressure fluctuations

“pressure reservoir”

Arteries - Muscular (distributing)

Smaller diameter

mainly smooth muscle

Large Arterioles

still muscular

Small Arterioles

begin losing musculature

Capillaries

Single cell layer (endothelial)

~1000 m2 surface area

Conts Capillaries

Muscle, lung, adipose, CNS

Fenestrated Capillaries

Pores in cell

Kidneys, endocrine glands, intestines

Disconts Capillaries

Gaps between cells

Bone marrow, liver, spleen

Precapillary sphincters

Control flow through capillary bed

Arterial end (O2 rich)

Hydrostatic > osmotic pressure

Net movement out (more)

Venous end (CO2 rich)

Osmotic > hydrostatic pressure

Net movement in (less, ~ 9/10)

Overall Capillary fluid exchange

Fluid movement out > movement in

Excess fluid removed by lymphatic system

Edema

Tissue fluid accumulation

Possibly caused by:

• High arterial pressure
• Venous obstruction (clot)
• Plasma protein leakage

• dec in plasma protein concentration (liver disease)
• Lymphatic obstruction (elephantiasis – parasitic)

Precapillary sphincter constriction

dec hydrostatic pressure

Same osmotic pressure

Possible flow reverse (… but more in)

Venules

Merger of capillaries

Veins (some smooth muscle)

Merger of venules

Volume reservoir (distensible)

Blood flow in veins

low pressure

skeletal & smooth muscle contractions aid

Flow direction in veins

Aided by one-way valves

Anastomoses

> 1 blood vessel supplies tissue

Alternate routes (collateral channels) for blood

Vasoconstriction & vasodilation

extremely important factors in controlling flowg flow