Stimuli and Responses Flashcards
What does Indoleacetic acid do?
Moves around plant to control growth by diffusion and active transport, uneven distribution of IAA leads to uneven growth and bending of roots and shoots
How is the heart rate controlled
Uses SAN as myogenic
What does it mean that the heart is myogenic?
It can contract and relax without receiving nerve signals
What is the Sino Atrial Node?
The heart’s pacemaker, a bundle of tissues in wall of right atrium sending regular waves of electricity to walls of artium
What are the steps of controlling the heart rate?
SAN send electrical waves to walls of atria
Causes L and R atria to contract
Band of non conducting collagen tissue prevent waves from going straight from atria to ventricles
The electrical activity sent to Atrioventricular node
Slight delay, to allow all blood out of atria
AVN send info down Bundle of His (muscle fibres responsible for conducting electrical activity between ventricles and apex of heart
Bundle splits into small fibres = Purkyne tissues
Purkyne tissue carry signals into L and R muscular walls of ventricles
V’s contract blood into Aorta and Pulmonary artery
What influence does the brain have over the heart?
The brain controls the rate at which the SAN sends electrical waves across atria therefore controlling heart beat.
Controlled unconsciously by the medulla
What part of the brain controls the firing of the SAN?
The medulla Oblongata
What different stimuli affects the heart rate?
The blood pressure and pH levels
