Sixth Form RevisionAS and A-Level P.E. Monday 14th March Miss Bowe
Objectives Starter - Taboo Recap the conduction system of the heart Complete an exam style question Complete some random AS exam questions
Taboo Preparation for the game; Think of or find a topic in your AS textbook Write the topic at the top of the paper Below list 3 words that describe or are associated with the topic you have chosen Hand in your card to me Let’s play … Alveoli Gas exchangeLungsCapillaries
The Conduction System The heart is capable of increasing or decreasing cardiac output to meet the demand for oxygen needed by the working muscles. How is the heart regulatedto meet these changes?
Cardiac control centre (CCC) Located in the medulla oblongataof the brain. The CCC is responsible for regulating the heart. The CCC is controlled by the autonomic nervous system (ANS). AUTONOMICautomatic or involuntary
ANS Is under involuntary control and consists of: Sympathetic nervous system increaseHR (via accelerator nerve) Parasympathetic nervous system decreaseHR (via vagus nerve).
How does the CCC regulate HR? Each cardiac cycle is controlled by the CCC. The CCC initiates either the sympathetic or parasympathetic nervous systemto stimulate the SA node causing either…. An increase in HR A decrease in HR
INCREASE HR DECREASE HR CCC SYMPATHETIC NERVOUS SYSTEM PARASYMPATHETIC NERVOUS SYSTEM ACCELERATOR NERVE VAGUS NERVE SA Node
What factors affect the activity of the CCC? Neural control = chemo/baroreceptors Hormonal control = adrenalin Intrinsic control = venous return
Proprio-receptorsin muscles, tendons and joints, inform CCC that movement has increased.
Chemoreceptorslocated in aorta and carotid arteries detect decrease in blood pH due to increase of lactic acid and CO2 Baroreceptorsdetect increase in blood pressure, aorta and carotid arteries are sensitive to stretch
Exam question (May 2005) Cardiac Output is a determining factor during endurance activities. Describe how cardiac output is increased during endurance activities. [5 marks/5 points] 1. Chemo/Barorecetorsdetect. 2. Stimulate CCC 3. Initiates Sympathetic via accelerator. 4. Increased impulse at SA node. 5. Increased HR/SV = increased Cardiac Output