New User Special Price Expires in

Let's log you in.

Sign in with Facebook


Don't have a StudySoup account? Create one here!


Create a StudySoup account

Be part of our community, it's free to join!

Sign up with Facebook


Create your account
By creating an account you agree to StudySoup's terms and conditions and privacy policy

Already have a StudySoup account? Login here

BSC 216 Heart Part 2 9/1/2016

by: Vanessa Notetaker

BSC 216 Heart Part 2 9/1/2016 BSC 216

Marketplace > University of Alabama - Tuscaloosa > Biology > BSC 216 > BSC 216 Heart Part 2 9 1 2016
Vanessa Notetaker
GPA 3.71

Preview These Notes for FREE

Get a free preview of these Notes, just enter your email below.

Unlock Preview
Unlock Preview

Preview these materials now for free

Why put in your email? Get access to more of this material and other relevant free materials for your school

View Preview

About this Document

Thursday Lecture on the Heart including many images and simplified steps to circulation and contractions
Anatomy & Physiology II
Austin Hicks
Class Notes
Biology, Heart, Circulation, Anatomy & Physiology II
25 ?




Popular in Anatomy & Physiology II

Popular in Biology

This 4 page Class Notes was uploaded by Vanessa Notetaker on Monday September 5, 2016. The Class Notes belongs to BSC 216 at University of Alabama - Tuscaloosa taught by Austin Hicks in Fall 2016. Since its upload, it has received 19 views. For similar materials see Anatomy & Physiology II in Biology at University of Alabama - Tuscaloosa.


Reviews for BSC 216 Heart Part 2 9/1/2016


Report this Material


What is Karma?


Karma is the currency of StudySoup.

You can buy or earn more Karma at anytime and redeem it for class notes, study guides, flashcards, and more!

Date Created: 09/05/16
BSC 216 THE HEART Part 2 Electrophysiology  Voltage occurs when two points across a cell membrane have different electrical potentials  Membrane potential is the difference in charge across membrane in all cells o Resting membrane potential only occurs in electrically excitable cells  Ion gradient is the difference in concentration of ions across a plasma membrane  Current is a flow of ions or electrons on a gradient  Depolarization is moving a membrane potential to become LESS NEGATIVE  Repolarization is the return of a cell to resting membrane potential o Excitable cells go through a cycle of depolarization and repolarization Steps of Skeletal Muscle Fiber Contraction 1. Membrane is polarized 2. Acetylcholine opens sodium channels and sodium floods the cell and depolarize it 3. Depolarizing cell membrane propagates contracting the muscle 4. Sodium ions finally close and cell repolarizes and potassium reenters the cell Contractile Cell Action potential 1. Sodium channels open and membrane is rapidly depolarized 2. Sodium channels inactivated and potassium channels open causing repolarization 3. Calcium channels open and K leaves the cell prolonging depolarization 4. Sodium and calcium channels close as potassium leaks out, repolarizing the cell Difference between Contractile Cell Action Potential vs Skeletal Cell Action Potential  Plateau phase makes the cardiac cell action potential much longer o This allows the chambers of the heart enough time to fill with blood before the next contraction  Cardiac cell has a longer refractory period (period during which an excitable cell cannot be stimulated again)  Pacemaker Physiology  Sinoatrial node has a resting membrane potential that starts at -60 mV and increases from a constant but, slow inflow of sodium ions (pacemaker potential)  As the cell becomes full with sodium and potassium the threshold is reached at -40 mV and calcium and sodium ion channels open  Depolarization peaks at 0 mV  Potassium channels open and repolarization occurs  Pacemaker potential restarts with the closing of potassium channels  Each depolarization of SA node sets off ONE HEARTBEAT Pacemaker Cell Action Potential 1. Membrane slowly depolarizes through leaky channels 2. Calcium channels open and calcium enters fully depolarizing the cell 3. Calcium channels close and potassium channels open causing repolarization 4. Potassium channels remain open and cell repolarizes preparing cell to repeat this process Impulse Conduction to Myocardium  SA node conducts signal that stimulates two atria to contract almost at the same time  Signal slows down in AV node because of fewer gap junctions allowing ventricles to fill  Signal travels very quickly though AV bundle and Purkinje fibers o Purkinje allows ventricles to contract in unison to send blood to great arteries o Papillary muscles contract an instant before the ventricles depolarize  Ventricular systole moves up the heart from the apex o Contraction movement similar to wringing of a towel Cardiac Conduction System  Internal pacemaker and nervelike conduction pathways work together to coordinate heart contractions  Heart contracts independently from nervous system but, nervous system may influence the heart if necessary  Intercalated discs and gap junctions allow for coordinated contraction 1. SA node in right atrium near base of superior vena cava initiates heart beat 2. Signal spreads through atria 3. AV node located near right AV valve at lower end of interatrial septum 4. AV bundle forks into left and right branches that pass through interventrical septum towards apex 5. Purkinje fibers spread through the ventricular myocardium and the signal passes through gap junctions Summary of the Conduction System 1. SA node generates action potential which spreads to atrial cells and AV node 2. After AV node delays the signal action potential is conducted to the AV bundle and then to the right and left branches 3. Action potential spreads from bundle branches along the Purkinje fibers to the contractile cells of the ventricles Nerves in the Heart  Sympathetic nerves- “Fight mode” o Nerves located in SA and AV nodes, atrial and ventricular myocardium , aorta, pulmonary trunk and coronary arteries o Increase heart rate and contractions  Parasympathetic nerves “Flight mode” o Right vagus nerve leads to the SA node while the left vagus nerve leads to the AV node o Little/none enervation of myocardium o Reduces heart rate Electrocardiogram (ECG or EKG) The Cardiac Rhythm  Sinus rhythm is the normal heartbeat triggered by SA node  Ectopic focus is when another part of the heart fires before the SA node (NOT GOOD) o Nodal rhythm- when SA node is damaged and AV node fires first  No P wave o Intrinsic ventricular rhythm- both SA and AV nodes damaged and pacemaker needed  Arrythmia- abnormal heart rhythm o Can be caused by failure of conduction system to transmit signals  Bundle branch blocked or total heart blocked (damage to AV node) o Heart block ECGs lack QRS complex o Premature ventricular contractions have spontaneous firing of ectopic foci and ECGs lack a normal rhythm and characterized by very large ventricular depolarization o Ventricular defibrillation is characterized by sporadic ups and downs on ECG because there is no coordination of electrical signals  One form of cardiac arrest Contractile Activity of the Heart  Systole- atrial or ventricular CONTRACTION  Diastole- atrial or ventricular RELAXATION  Valve opening occurs as a result of pressure buildup  Lub-dub sound occurs as a result to the closing of the AV and semilunar valves o S1- closing of cuspid valaves o S2- closing of semilunar valves o Swishing indicates improper closing of valves Events of the Cardiac Cycle 1. Ventricular filling phase- ventricle diastole and atrial systole; AV valves open and semilunar closed 2. Isovolumetric contraction phase- ventricle systole and atrial diastole; AV and semilunar valves closed 3. Ventricular ejection phase- ventricle systole and atrial diastole. SL valves opened and AV valves closed 4. Isovolumetric relaxation phase- ventricle and atrial diastole. AV and SL valve closed


Buy Material

Are you sure you want to buy this material for

25 Karma

Buy Material

BOOM! Enjoy Your Free Notes!

We've added these Notes to your profile, click here to view them now.


You're already Subscribed!

Looks like you've already subscribed to StudySoup, you won't need to purchase another subscription to get this material. To access this material simply click 'View Full Document'

Why people love StudySoup

Bentley McCaw University of Florida

"I was shooting for a perfect 4.0 GPA this semester. Having StudySoup as a study aid was critical to helping me achieve my goal...and I nailed it!"

Amaris Trozzo George Washington University

"I made $350 in just two days after posting my first study guide."

Bentley McCaw University of Florida

"I was shooting for a perfect 4.0 GPA this semester. Having StudySoup as a study aid was critical to helping me achieve my goal...and I nailed it!"

Parker Thompson 500 Startups

"It's a great way for students to improve their educational experience and it seemed like a product that everybody wants, so all the people participating are winning."

Become an Elite Notetaker and start selling your notes online!

Refund Policy


All subscriptions to StudySoup are paid in full at the time of subscribing. To change your credit card information or to cancel your subscription, go to "Edit Settings". All credit card information will be available there. If you should decide to cancel your subscription, it will continue to be valid until the next payment period, as all payments for the current period were made in advance. For special circumstances, please email


StudySoup has more than 1 million course-specific study resources to help students study smarter. If you’re having trouble finding what you’re looking for, our customer support team can help you find what you need! Feel free to contact them here:

Recurring Subscriptions: If you have canceled your recurring subscription on the day of renewal and have not downloaded any documents, you may request a refund by submitting an email to

Satisfaction Guarantee: If you’re not satisfied with your subscription, you can contact us for further help. Contact must be made within 3 business days of your subscription purchase and your refund request will be subject for review.

Please Note: Refunds can never be provided more than 30 days after the initial purchase date regardless of your activity on the site.