Post on 24-Jul-2015
In order to live and interact with our world, we need to have ways of getting information
Sensing danger
Avoiding Damage
We need to be able to collect
information, process it
and respond to it.
Getting Around
We have sense organs
SkinEyesEarsTaste budsNose
These collect a multitude of information so we can understand and interact with our world
Some senses cause an instant response
Senses are picked up by receptors
Chemoreceptors sense chemicals (smell, taste)
Nociceptors sense pain
Mechanoreceptors sense pressure , light touch & stretch
Thermoreceptors sense temperature changes
Photoreceptors sense light and shadow and colours
Sensory Nerves
Sensory receptors start electrical impulses along sensory nerve fibres to be processed.
The cell body decides how to respond, sending impulses
to other neurons to cause an effect (Right) – reflex action
to alert the conscious brain to the stimulus.
Sensory Neuron Structure
Receive input from a receptor OR from another neuron at the dendrites
Pass the message to the cell body and then down the axon to pass the message on to other neurons.
Peripheral Nerves
Dendrites receive information
Cell body manages information
Axon conducts signal ultra fast because of myelin sheath
Terminal buds interact with another nerve cell dendrites or effector organ eg muscle
Sensory Motor Reflex
Signal sent to
interneuron
receptor
• Passes message to motor nerve
• Simultaneous message sent to brain
interneuron
• Signal to muscle
• Muscle contraction
Motor
nerve
Nervous System
The Rapid Response System for stimuli that require immediate action that is short lasting and has no permanent change on the body
Endocrine System
Sometimes the body needs a longer lasting response that the nervous system cannot coordinate
This is where chemical messages, called hormones play a role in controlling body systems
The endocrine system controls the release of hormones
Hypothalamus – receives information about internal body and sends messages to glands to in response
Pineal Gland – manages day/night cycle
Pituitary Gland – master control
Thyroid/Parathyroid Gland – controls metabolism
Thymus Gland
Adrenal Gland – fight and flight response
Pancreas – controls digestive enzymes and insulin
Ovary/Testes – controls sexual cycles
Hormones
Insulin in the PancreasReleased in response
to sugar levels in the blood
Acts to store the excess sugar in cells for later use when needed
Glucagon is the opposite acting hormone and releases sugars when blood sugars are low
Adrenal Glands
Near the kidneys, the adrenal glands act when a body is under stress
Release of adrenaline Increased heart rate Increases blood flow to the muscles Increase blood pressure Increase metabolic rate
Hormones Are often in the blood at varying
concentrations.
Hormones
Act slowly Seconds - adrenal Minutes- pancreasHours, days, months, years – sex hormones
Long lasting response that may be reversible or not
Summary of Control Systems
Via 2 systems (fast and slow)
Keeps the body at optimum function
HOMEOSTASIS – the state of the body is kept within normal parameters, eg blood sugar, blood pH, temperature of the body