Class Notes (839,150)
Canada (511,218)
Biology (91)
BIL 118 (28)


3 Pages

Course Code
BIL 118
O' Sullivan

This preview shows page 1. Sign up to view the full 3 pages of the document.
Electrophysiology  Sinus node is located at the top right atrium o Also known as the "natural pacemaker" controlling heart rate o Increases with physical activity and decreases when relaxing o Electrical signal rapidly spreads from the Sinus node across the right atrium and left atrium  Only one area where atria and ventricles are electrically connected o Atrioventricular node or AV node deep in center of heart o All electrical signals from atrium must pass through AV node in order to get to ventricles o AV node is connected to the Bundle of His o Branches into a right bundle (to right ventricle) and left bundle (to left ventricle)  Fibers that branch out to distant ventricular tissues are called Purkinje Fibers Blood pressure  Baroreceptors near aorta and carotid arteries monitor blood pressure  Abnormal blood pressure → signal send to medulla  Cardiac center changes heart rate → cardiac output  Vasomotor center changes diameter of blood vessels  Shock: blood pressure too low o Insufficient nutrients for cells with a high metabolism (heart, brain) o Caused by excessive bleeding or extensive vasodilation o Treated with vasoconstrictors such as epinephrine (adrenaline), atropine o [NOTE] International name for adrenaline is now epinephrine Regulation of the Cardiac Cycle  Heart has unique ability to beat (contract) on its own  Assisted by nerves and hormones in blood but functions without them  Impulse leaves SA node and passes through both atria → causing them to contract  From AV node impulse passes down to the Bundle of His  Bundle of His branches and spreads through both ventricles via Purkinje fibers → ventricles contact Cardiac output as a function of stroke volume and heart rate  The volume of blood pumped by one ventricle during one beat is called the stroke volume  Cardiac Output = Stroke Volume x Heart Rate (number of ventricular contractions/min)  ↑Force of contraction → ↑Stroke volume → ↑Cardiac output Regulation of heart rate → Cardiac output is influenced by several factors Autonomic Nervous System  Heart is innervated by the autonomic nervous system (ANS) o The autonomic nervous system has 2 divisions o These division are called parasympathetic and sympathetic o Parasympathetic fibres decrease heart rate via the vagus nerve o Sympathetic fibres increase heart rate  Cardiac Inhibitory Centre o Found in the medulla oblongata of the brain stem
More Less
Unlock Document

Only page 1 are available for preview. Some parts have been intentionally blurred.

Unlock Document
You're Reading a Preview

Unlock to view full version

Unlock Document

Log In


Join OneClass

Access over 10 million pages of study
documents for 1.3 million courses.

Sign up

Join to view


By registering, I agree to the Terms and Privacy Policies
Already have an account?
Just a few more details

So we can recommend you notes for your school.

Reset Password

Please enter below the email address you registered with and we will send you a link to reset your password.

Add your courses

Get notes from the top students in your class.