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