Anatomy and Physiology Unit 5 Sophie Bevan
‘The same state’ Equilibrium Negative feedback Homeostasis The way your body attempts to maintain constant internal conditions in an ever- changing external environment.
Homeostatic regulation involves three parts or mechanisms: 1)the receptor 2) the control center and 3) the effector.
Objectives Make your own notes on the regulation of the following for your assignment - Blood Glucose Regulation - Heart Rate Regulation - Body Temperature Regulation - Respiratory rate Regulation
Heart Rate Regulation Heart rate is controlled by the CCC in the brain The cardiovascular control centre is in the medulla of the brain. (Brainstem)
Heart Rate Regulation The CCC is controlled by the ANS The automatic (involuntary) nervous system has two branches Sympathetic nervous system Parasympathetic nervous system
Sympathetic Nervous System Increases strength of heart beat Increases rate of heart beat FASTER
Parasympathetic Nervous System Decreases strength of heart beat Decreases rate of heart beat SLOWER
The cardiac control centre initiates either sympathetic or parasympathetic nerves to stimulate the sino-atrial node to increase or decrease heart rate.
During Exercise More oxygen is needed More glucose and nutrients are needed Blood carrying these components needs to be delivered fast…. Sympathetic nervous system (SNS) is stimulated, sending impulses via the spinal chord to make the heart beat faster and stronger
Electrical impulses generated from your SAN move through the heart to the AV node This is conducted down the bundle of his and spread through the purkinji fibres
Adrenaline (hormone) also released at the same time (from adrenal glands) to increase the speed of heart contraction
After Exercise Parasympathetic nervous system (PSNS) is stimulated to slow down the heart rate Impulses are sent from the Cardio- inhibitory center in the medulla via the vagus nerve to the heart, to make the heart beat slower and weaker
How does the ANS work? Baroreceptors (stretch receptors) detect change in size of blood vessels e.g blood pressure Receptors relay this information to your brain (medulla) Vasomotor control center in the medulla of the brain then redistributes blood through vasodilation and vasoconstriction
Chain Low blood pressure – detected by baroreceoptors – brain stem – medulla – vasomotor centre – spinal chord – nervous impulses