Exercise / Heart activity Flashcards
Cardiac Muscle
This is myogenic so it can contract without receiving signals from neurones
Cardiac Muscle controls Heart Beats
1) Starts in SAN in right atrium
2) SAN sends waves of electrical activity atrial walls causing them to contract at the same time
3) Waves are transferred to AVN, these pass the activity to the bundle of HIS. This is delayed to ensure the atria and ventricles contract at different times
4) Bundle of His conducts the waves to the purkyne fibres that cause the ventricles to contract.
Electrocardiographs
These record electrical activity of the heart
- P wave: The depolarization of the atria
- QRS complex: This is the depolarization of the ventricles
- T wave: Repolarisation of the ventricles
Increase of breathing and Heart rate during Exercise
When exercising your muscles contract more and need more energy so more oxygen is needed. There are 2 ways the body increases oxygen
- Increase breathing rate and depth to obtain more oxygen and release more Co2
- Increase Heart Rate so oxygen can be delivered faster to muscles
Medulla Oblongata and Breathing rate
The medulla contains breathing centres ( inspiratory and expiratory)
- Medulla sends impulses to intercostal and diaphragm muscles to contract
- This increases volume and increases the intake of oxygen. The expiratory centre is inhibited
- As lungs inflate stretch receptors detect this and send impulses back to medulla and inspiratory centre is inhibited
- The expiratory centre sends impulses to cause muscles to relax and stretch receptors are inactivated.
Exercise triggers increased Breathing rate by decreasing PH in blood
The Co2 in the blood increases, decreasing blood PH
- Chemoreceptors detect the drop and send impulses to the medulla.
- The medulla then sends more frequent impulses to the muscles to increase breathing rate and depth
- This causes a faster gaseous exchange and Co2 levels drop.
Medulla and Heart Rate
High Blood Pressure :
- Baroreceptors detect high B.P and send impulses to the Cardiovascular control centre along the parasympathetic neurone. The SAN then fires fewer impulses to reduce blood pressure.
- Low Blood Pressure: Baroreceptors detect a change and send impulses along the sympathetic neurone. the SAN fires more frequent impulses to increase blood pressure.
High PH Levels:
- Chemoreceptors detect this send impulses to medulla via parasympathetic neurones. SAN fires less frequent impulses to decrease PH levels back to normal
Low PH levels- Chemoreceptors detect a change and send impulses along the sympathetic neurones. SAN fires more impulses frequently to increase HR and return PH to normal
Cardiac Output
C.O = HR*Strole volume
- Stroke vol= vol. of blood pumped out by one ventricle each time it contracts
- Cardiac Output = Total vol. of blood pumped by a ventricle in a minute
Tidal Volume
T.V= Vol. of air in each breath
- Breathing rate= How many breaths were taken in a minute
- Respiratory minute ventilation= Tidal vol. * breathing rate
Spirometers
- Oxygen filled chamber with moveable lid
- A person breathes into a tube
- Breathing in and out for a set time
- The vol. of oxygen will decrease as it is inhaled and carbon dioxide is absorbed by soda lime
Homeostasis
This is the maintenance of a stable internal environment
- Homeostasis maintains equilibrium in the body
- If body temp. goes too high enzymes denature as they vibrate too much, the binding site changes shape and bonds break.
- Water levels, glucose levels, temperature and hormones are all controlled by homeostasis
Negative Feedback
Receptors detect when levels are too high or too low
This is passed on by the nervous system to effectors
The effectors counteract the change and bring levels back to normal
Negative feedback works in limits if the change is too big it may not be fixed.
Mechanisms to maintain body temperature
REDUCE body temp:
- Sweating: more sweat is secreted and heat is lost due to evaporation
- Hairs lie flat: Erector pili muscles relax so hairs lie down to prevent insulation so more heat is lost
- Vasodilation: Capillaries near the skin surface dilate to increase blood flow to the skin, more heat is lost via radiation
INCREASE body temp:
- Shivering: This causes muscle contraction which increases body temperature
- Less sweat produced so heat isn’t evaporated
- Hairs stand up and insulate the body
- Vasoconstriction: Blood is shunted to the core of the body and capillaries near the skin constrict so less heat is radiated
- Hormones like adrenaline cause metabolism to increase which produces heat
Hypothalamus Role
Maintains body temperature
- Thermoreceptors detect temperature change
- Sensory neurones send impulses to the hypothalamus which sends impulses down motor neurones to effectors.
- The effectors respond and restore body temperature.
Hormones can affect transcriptional factors
Transcriptional factors are proteins that control the transcription of genes
- They bind to DNA to increase or decrease transcription rate
Hormones affect this
- They can bind to the T.F inside of on the membrane receptors
