Nervous control

• Nervous system consists of central nervous system (CNS) and other nerves.
• CNS consists of brain and spinal cord.
• Structure and function of parts of the brain – cerebrum, cerebellum and medulla.

Nervous control

• Neurons are of three types: sensory, inter and motor.
• Sensory neurons pass the information to the CNS.
• Inter neurons operate within the CNS, which processes information from the senses that require a response.
• Motor neurons enable a response to occur at an effector (muscle or gland).
• Receptors detect sensory input/stimuli.
• A response to a stimulus can be a rapid action from a muscle or a slower response from a gland.
• Electrical impulses carry messages along neurons.
• Chemicals transfer these messages between neurons, at synapses.

Structure and function of reflex arc

Reflexes protect the body from harm.

1. Stimulus detected by receptor
2. Impulse travels along sensory neuron
3. Inter neuron passes on impulse, via spinal cord
4. Motor neuron sends impulse to effector

Hormonal control

Features of hormones

• Made of protein
• Chemical messengers
• Specific for some (target) tissues
• Shaped to fit receptors
• Released or produced by endocrine glands/ system
• Carried in blood
• Can have a long term effect

Hormone function

• Endocrine glands release hormones into the bloodstream.
• Hormones are chemical messengers.
• A target tissue has cells with complementary receptor proteins for specific hormones, so only that tissue will be affected by these hormones.

Blood glucose regulation

• Pancreatic receptors detect changes in blood glucose concentration.
• Pancreas then secretes either more insulin (blood glucose increase) or glucagon (decrease).
• Liver responds to hormone by either converting excess glucose to stored glycogen OR breaking down stored glycogen to release glucose into blood.

Topic Summary