Answer these questions 1 Intrinsic and hormonal systems

Answer these questions… 1. Intrinsic and hormonal systems influence the heart during physical activity. A swimmer completes a 1500 m race, with sub-maximal effort, in 20 minutes. Describe the variations in heart rate and how these changes are achieved during the race. [4 marks]

• How do neural factors regulate heart rate during physical activity and during gradual recovery? [5 marks]

Answer to Q 1. • Heart rate rapidly increases • Proprioceptors detect movement. • Production of CO 2/increased blood acidity/ph falls/increase in H+ ions • Stimulates chemoreceptor (in aorta/carotid body) • Stimulates medulla in brain • sympathetic nerve is stimulated/release of adrenaline/noradrenalin/norepinephrine • Sino atrial node stimulated

Answers to Q 2 During activity • Chemoreceptors detect decreases in O 2/ p. H of the blood/increases acidity /CO 2/Lactic acid • Proprioreceptors detect movement • Baroreceptors detect increases in blood pressure • Messages are sent to the cardiac control centre/ CCC (in the medulla oblongata) • S/A node stimulated / the (cardiac) accelerator nerve SA node reference only when linked to physical activity(not recovery) • The sympathetic nervous system increases heart rate During recovery • Chemoreceptors detect increases in the O 2/ p. H of the blood/ decreases in acidity /co 2/Lactic acid • Proprioreceptors detect reduction in movement • Baroreceptors detect decreases in blood pressure • Messages are sent (to the S/A node) via the vagus nerve • The parasympathetic nervous system decreases heart rate.

Definitions of the Heart DEFINITION STROKE VOLUME AMOUNT OF BLOOD EJECTED IN ONE (SV) BEAT HEART RATE (HR) RESTING VALUE 70 -80 ML NUMBER OF BEATS IN 1 MIN 70 -90 bpm CARDIAC OUTPUT STROKE VOLUME x HEART RATE Q = SV x HR APPROX 5. 6 LITRES * Values relate to an untrained person

Values During Exercise Stroke Volume At Rest During Exercise 70 -80 ml 140 -190 ml Heart Rate 70 -90 bpm 120 -200 bpm Cardiac Output 5. 6 L/min 19. 81 L/min

Blood Pressure • http: //www. youtube. com/watch? v=T 9 QKj 89 a jko

During exercise, blood pressure increases

Venous Return • You are going to watch a video clip. When watching the clip, write down the 3 mechanisms that assist venous return. • http: //www. youtube. com/watch? v=e. Cs. F 4 eyx xy. A

Vascular Shunt • The redistribution of blood during exercise. • During exercise, we need more blood to be delivered to the working muscles. • Therefore, we need to reduce the amount of blood going to places that do not need it so we can send more to the places that do. • E. g. blood is not needed in the digestive system during exercise, so blood is restricted to this area.

Vascular Shunt • In order to make this happen, 2 things occur: 1. Vasoconstriction 2. Vasodilation • Vasoconstriction is where the arterioles and precapillary sphincters supplying the organs with blood get smaller to allow less blood through. • Vasodilation is where the arterioles and precapillary sphincters supplying the muscles with blood get bigger to allow more blood through.

Vascular Shunt • Controlled by the VCC (vasomotor control centre) • Chemoreceptors and baroreceptors inform the VCC. • Increases sympathetic nerve stimulation to organs • This activates vasoconstriction. • Decreases sympathetic nerve stimulation to the muscles. • This activates vasodilation

Quick recap • http: //www. teachpe. com/anatomy/blood_flo w. php

Answer this question… • Sketch a graph to show a typical heart rate response of a healthy 18 year old to a submaximal 10 minute warm-up training run with a 5 minute recovery period. [5 marks]

In pairs… • Describe to your partner the flow of blood through the systemic circulatory system • Tell your partner how blood flows through the vascular system and what changes in pressure occur as this happens.