Do Now 11/5/14 1.Which chambers of the heart act as pumps? 2.Where does blood go after it leaves the right ventricle? Through what valve does it pass? 3.What are the substages of systole? Describe the relaxation/contraction of the chambers and the opening/closing of valves at each substage. 4.What are the substages of diastole? Describe the relaxation/contraction of the chambers and the opening/closing of valves at each substage.

Regulation of the Heart

agenda Do Now5 min Quiz20 min Regulation of the heart15 min Practice10 min RAFT10 min ECG15 min Exit Ticket5 min

Objectives By the end of today’s class period, I will be able to … Describe the control centers of the heart Describe how the heart receives electrical impulses Describe what an ECG is and how it is interpreted

Regulation of the heart There are three regulation mechanisms of the heart 1 internal – sinoatrial node 2 external – medulla oblongata, endocrine system

Internal control The sinoatrial node (pacemaker) produces an electrical impulse which tells the heart to beat. It is located in the right atrium.

Two forms of external control Medulla Oblongata: located in the brain Endocrine system

The cardiac center The cardiac center is located in the medulla oblongata Controls the autonomic nervous system

The autonomic nervous system Baroreceptors located in the atria, aortic arch and carotid arteries monitor blood pressure and send info to the cardiac center Autonomic nervous system: Sympathetic branches increase heart rate Parasympathetic branches decrease the heart rate

The endocrine system Glands in the endocrine system secrete hormones Epinephrine (adrenaline), norepinephrine, and thyroxine increase the heart rate

The Conduction system The conduction system transmits signals which control heart rate and contraction strength

The pathway of an electrical impulse 1.The sinoatrial node creates the impulse 2.The impulse goes to the left atrium and the atrioventricular node (between the right atrium and right ventricle) – atria contract 3.The impulse travels down the atrioventricular bundles in the interventricular septum (middle of the heart) to millions of Purkinje fibers 4.The Purkinje fibers stimulate the ventricles to contract.

The pathway of an electrical impulse 1.The sinoatrial node creates the impulse 2.The impulse goes to the left atrium and the atrioventricular node (between the right atrium and right ventricle) – atria contract 3.The impulse travels down the atrioventricular bundles in the interventricular septum (middle of the heart) to millions of Purkinje fibers 4.The Purkinje fibers stimulate the ventricles to contract.

View the heart animations at McGraw Hill to understand the Cardiac Cycle McGraw Hill

Practice Discuss all of the following questions with your partner, but do not shout out. I will call on one person to answer each question

Question #1 What are the 3 different mechanisms that regulate the heart? #1. Sinoatrial Node #2. Cardiac center in the medulla oblongata #3.Endocrine System

Question #2 What is another term for the sinoatrial node? What does it do? Pacemaker. It creates electrical impulses to tell the heart to pump.

Questions #3 The cardiac center has two branches of fibers that send messages to the brain. What is this nervous system called? What are the branches called? Autonomic Nervous System Sympathetic and Parasympathetic Branches

Question #4 Describe the difference between the roles of the sympathetic and parasympathetic branches. Sympathetic increases HR Parasympathetic decreases HR

Question #5 List the order in which an electrical impulse travels through the heart. #1 originates in the sinoatrial node #2 Travels to the Left Atrium and the Atrioventricular Node #3 Travels from the AV node down the center of the heart. #4 The signal splits to go to each ventricle through the Purkinje fibers

RAFT (role audience format topic) The body contains many pathways for electrical impulses, of which the heart is just one pathway. Write a journal entry as if you are a nerve impulse the usually works in the muscular system but are sightseeing in the heart’s control center. Role – nerve impulse Audience – fellow nerve impulses working the muscular system Format – journal entry Topic – you usually work in the muscular system but you are sightseeing in the heart’s control center. Begin at the cardiac center and end at the Purkinje fibers.

Electrocardiogram (ECG) Interpretation of the electrical activity of the heart over a period of time as detected by electrodes attached to the surface of the skin

ECG – electrocardiogram – a recording of the electrical events (changes) during a cardiac cycle P Wave – depolarization of the atria (atrial contraction – systole) QRS Complex – depolarization of the ventricles (ventricular contraction, systole) T Wave – Repolarization of the ventricles Heart Sounds – opening and closing of the valves, flow of blood into and out of the chambers, vibrations in muscle

Interpreting ECGs An ECG is printed on paper covered with a grid of squares. Notice that five small squares on the paper form a larger square. The width of a single small square on ECG paper represents 0.04 seconds. A common length of an ECG printout is 6 seconds; this is known as a "six second strip."

Types of Arrhythmia Arrhythmia – abnormal heart rhythm causing the heart to be unable to pump blood effectively Bradycardia – heart rate below normal range, resting heart rate under 60 BPM Tachycardia – heart rate exceeding normal range, resting heart rate over 100 BPM

Analyze an ECG Each one of the figures represents an ECG pattern displaying three types of abnormal rhythms: Tachycardia, Bradycardia, and Arrhythmia. Identify each.

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