Bio 142 exam 2

Arteries

carry blood away from the heart

Veins

carry blood back to the heart

Capillaries

are sites of exchange

Between blood and air in lungs

Between blood and body cells

Pulmonary circulation

Carries deoxygenated blood from right side of heart

to lungs

 At lungs, blood picks up oxygen and releases

carbon dioxide

 Blood vessels return blood to left side of heart

Systemic circulation

Moves oxygenated blood from left side of heart to

systemic cells

 At systemic cells (e.g., skin, muscles), blood

exchanges gases, nutrients, and wastes

 Blood vessels return blood to right side of heart

Fibrous pericardium

Dense irregular CT

Protects and anchors the hear prevents overstreching

myocardium

cardiac muscle layer is the bulk of the heart

myocartditist:inflamation of the myocardium

Pericarditis

inflammation of the pericardium

Serous Pericardium

thin delicate membrane

contains parietal layer-outer layer

 pericardial cavity with

pericardial fluid

 visceral layer (epicardium)

Pericardial effusion

collection of fluid in the

pericardial space

Cardiac tamponade

Associated bleeding into the

pericardial cavity that compresses the heart and is

potentially lethal

chordae tendinae and papillary muscle funciton

to help open and close the AV valves

SL valves open with-

ventricular contraction-allow blood to flow from ven to pulmonary trunk or aorta

Sl valves close with-

ventricular relaxation-prevents blood from returinnig,blood fills valve cusps, tightly closing the SL valves

Stenosis

is a narrowing of a heart valve

which restricts blood flow.

 Insufficiency or incompetence is a failure

of a valve to close completely.

Heart Murumurs

abnormal heart

sounds produced due to turbulence of

blood flowing through a narrowed or

incompetent heart valve.

Coronary Circulation

Coronary circulation is blood supply to the heart

Heart as a very active muscle needs lots of O2

 When the heart relaxes, high pressure of blood in

aorta pushes blood into coronary vessels

Coronary Artery Disease (CAD)

Heart muscle receiving

insufficient blood supply

 narrowing of vessels---

atherosclerosis, artery

spasm or clot

 atherosclerosis--smooth

muscle & fatty deposits

in walls of arteries

Coronary Artery Disease (CAD) treatment

drugs, bypass graft,

angioplasty, stent

Risk Factors for Heart Disease

Risk factors in heart disease:

 high blood cholesterol level (LDL & VLDL)

 high blood pressure

 cigarette smoking

 obesity & lack of regular exercise

 Other factors include:

 diabetes mellitus

 genetic predisposition

 male gender

 high blood levels of fibrinogen

 left ventricular hypertrophy

Myocardial Ischaemia

Reduced blood flow through coronary arteries leading to less

oxygen supply to myocardial cells.

Myocardial Infarction

complete obstruction of flow in a coronary artery may

cause myocardial infarction (heart attack).

Working cells or Contractile cells

Wall of atria & ventricles

 Responsible for contraction & relaxation of

the heart

Conducting cells or Autorhythmic cells

Specialised cardiac muscle cells

 Capable of producing an electrical impulse

Autorhythmic cells

are self-excitable.

 generate spontaneous action potentials that then

trigger heart contractions.

 act as a pacemaker to set the rhythm for the

entire heart.

SA node

pacemaker of the heart

 Generates electrical impulses at the fastest rate compared to other

parts of the conducting system

90 – 120 impulses/min

AV node

40 – 60 impulses/min

AV (His) Bundle & Purkinje fibres

20 – 40/min

Normal range for heart rate

60 – 90 beats / min

Tachycardia

HR > 100 beats / min

Bradycardia

HR < 60 beats / min

Factors affecting the increase in heart rate

Sympathetic nerves

increase HR and increase the force of contraction

increase body temperature: increase HR

Respiration

HR increase slightly during inspiration

Factors affecting the decrease in Heart rate

Parasympathetic nervers (vagus nerve)

Decrease HR and Decrease force of contraction

Body temp

Decrease body temp decrease HR

Respiration

HR decrease slightly during expiration

Hormones & Chemical substances :affecting heart rate

epinephrine, norepinephrine, thyroid hormones: 

HR

 Acetylcholine:  HR

Electrocardiogram (ECG)

Record of the electrical activity of the heart

 Records the spread of electrical impulse through the heart

during each heart beat

 Can be recorded from the surface of the skin using

electrodes

Standard limb leads

Bipolar limb leads

 Measures the potential difference between 2 active electrodes

placed on the limbs

 Lead I, Lead II, Lead III

Augmented limb leads

Augmented unipolar leads

 Measures the potential difference between an active electrode

and an indifferent electrode

 aVR, aVL, aVF

Precordial or chest leads

Unipolar leads

 V1 – V6

P wave

Atrial depolarization (spread of electrical

impulse through the atria)

QRS complex

ventricular depolarization (spread of

electrical impulse through the ventricles)

T wave

Ventricular Repolarization

R-R

entire duration of a cardiac action potential

P-R interval

time taken for conduction of electrical

impulse from atria to ventricles

Q-T interval

Entire duration of a ventricular action potential

Uses of ECG

Heart rate

 Rhythmicity

 Conduction abnormalities

 Heart size

 Effect of ionic changes and drugs on

heart (hypokalemia, hyperkalemia,

hypocalcemia, hypercalcemia)

 Myocardial ischaemia or infarction

 Heart diseases

Arrythmia

is an irregularity in

heart rhythm resulting from a defect in the

conduction system of the heart.

 Categories are bradycardia, tachycardia, and

fibrillation.

stroke volume

the amount of blood pumped by each ventricle during a single heart beat 70-90mL

cardiac output

the amount of blood pumped by each ventricle during a single heart beat per minute

resting CO=5000-6000mL per min

how to calculate cardiac output

CO=stroke volume x HR(bpm

Cardiac Reserve

Capacity to increase cardiac output above rest level

 HR accelerates and stroke volume increases during exercise

 CO can increase four-fold in a healthy non-athlete and up to seven-

fold in athlete

Ejection fraction

percentage of blood (out of total amount) that is ejected with each

ventricular systole

 equal to stroke volume divided by EDV

 normal ejection fraction is about 50–65% for each ventricle

Cardiac Cycle

Is the period between the start of one heartbeat and the beginning

of the next

 Includes both contraction and relaxation

Ventricular contraction

V valves pushed closed

 Semilunar valves pushed open and blood ejected to artery

Ventricular relaxation

Semilunar valves close

 No pressure from below keeping them open

 AV valves open

 No pressure pushing them closed

Ventricular filling phase

All heart chambers are relaxed

 Atrial blood pressure forces AV valves

open and blood flows into ventricles

 Semilunar valves remain closed since

arterial pressure is greater than ventricular

pressure

Atrial systole

SA node starts atrial excitation

 Atria contract pushing remaining blood into ventricles

 Ventricles filled to end-diastolic volume (EDV) (120-140ml)

 Atria relax for remainder of cardiac cycle

Isovolumetric contraction phase

Purkinje fibers initiate ventricular excitation

 Ventricles contract, pressure rises, and AV valves are pushed

closed

 Ventricular pressure is still less than arterial trunk pressure, so

semilunar valves still closed

Ventricular ejection phase

Ventricles continue to contract so that ventricular

pressure rises above arterial pressure

 Semilunar valves forced open as blood moves from

ventricles to arterial trunks

Stroke volume (SV)

is amount of blood ejected by

each ventricle (70 – 90 mL)

End systolic volume

(ESV) is amount of blood

remaining in ventricle after contraction finishes

Isovolumetric relaxation phase

Ventricles relax and start to expand, lowering

pressure

 Arterial pressure greater than ventricular pressure

 By sliding back toward ventricles, blood closes

semilunar valves

 AV valves remain closed

 When all valves are closed, blood neither enters nor

leaves and the time is called “isovolumetric”

At 75 beats/min, one cycle requires how many seconds

0.8sec

End diastolic volume (EDV)

volume in ventricle at end of diastole, about 130ml

End systolic volume (ESV)

volume in ventricle at end of systole, about 60ml

Stroke volume (SV)

the volume ejected per beat from each ventricle, about 70ml

 SV = EDV - ESV

Auscultation of the Chest

act of listening to sounds within the body

 usually done with a stethoscope

factors affecting CO = Where heart rate increases

Anxiety/stress(corisol)

pain

hyperthyroidism

exercise

fever

pregnancy medications

caffeine

factors affecting CO = Where heart rate decreases

sleep

hypothyroidism

hypothermia

hypokalemia hypocalcemia

myocardial infarction

Factors affecting C = where stroke volume increases

Venus return

and contractility of the Ventricles

Venus return

the amount of blood returning to the heart

in a heathy normal condition, it should be the same as the CO

Frank-Starling Law of the Heart

Relationship between preload and stroke volume is

explained by mechanism known as Frank-Starling law

 Within physiological limits, the force of contraction of the

heart is directly related to the degree to which the

ventricular muscle is stretched during diastole

preload

Stretch of the ventricular walls before they contract

Contractility of the Ventricles

Force of contraction of the ventricles during

ventricular systole

Contractility can be affected by

Autonomic nerves

 Hormones

Afterload on the Heart

refers to force that right and left ventricles must

overcome in order to eject blood into their respective

arteries

Elasticity

allows arteries to expand & receive blood

under great pressure during contraction of the

ventricles and to recoil back propelling the blood

through the system.

Contractility

smooth muscle in the tunica media,

allows arteries to increase or decrease lumen size

and to limit bleeding from wounds.