Regulation Nervous and Endocrine Systems

Parts of the nervous system… Brain Spinal Cord Nerves

Functions of the nervous system Communication between body systems Helps body react to changes in the environment Helps body maintain Homeostasis

Neurons are the basic component of the nervous system. Dendrites: Receives impulse Cell Body: contains nucleus and other organelles Axon: Sends impulse Myelin sheath: fatty substance that insulates the axon and makes impulses travel faster.

Synapse: gap between neurons Neurotransmitters: chemical that carries impulse across the synapse. –Inhibitory: blocks signal –Excitatory: increases signal Receptors: receive neurotransmitters.

Types of Neurons Sensory neurons: signal goes from a receptor to the spine or brain Inter-neurons: signal goes from one neuron to another neuron Motor neurons: signal goes from brain or spine out to a muscle or gland.

Path of message: Stimulus: causes receptor to react Receptor: a sense organ such as the eyes, skin, ears… Impulse: the message or signal carried along the neuron Effector: an organ that responds to the impulse.

Types of stimuli: Types of receptors: Types of effectors:

The nervous system is divided into two parts… Central Nervous system (CNS) –Brain –Spine Peripheral Nervous System (PNS) –Nerves

The Brain: The brain is one of the most active organs in the body. It receives 20% of the blood the heart pumps and it replaces most of its protein every three weeks. The brain is a major user of glucose. You can burn lots of calories just by using your brain!

Parts of the Brain Cerebrum: –Largest part of brain –Divided into a right and left hemisphere –Used for thinking, movement, sensation, etc.

Cerebellum: –At the base of the brain –Used for balance and coordination

Brain Stem –Medulla oblongata: heart beat, respiration –Pons: relay center –Midbrain: relay center

Memory Occurs in the Cerebrum –Momentary: a few minutes –Short Term: a few hours –Long Term: years

Spinal Cord Structure: a bunch of nerves that run through your vertebral column. Function: sends messages to and from the brain and body. Connects the CNS to the PNS

Peripheral Nervous System Nerves –Cranial = out of brain –Spinal = out of spine Somatic Nervous system: in charge of voluntary actions. Autonomic Nervous system: In charge of involuntary actions.

Reflexes Examples:

Reflex Arc 1. Receptor is stimulated 2. Sensory neuron sends impulse to spine. 3. Sensory neuron connects to an interneuron which connects to a motor neuron. 4. Motor neuron sends impulse to muscle. Reflex occurs.

Endocrine System The job of the Endocrine System is to regulate the body and help it maintain homeostasis.

Hormones: Chemical messengers that communicate with target cells.

The endocrine system is slower than the nervous system but, its effects last longer (hours to years)

Glands Exocrine Glands: secret their products outside of the body or in the digestive system. Endocrine Glands: secrete their products in the blood stream.

Hormones are specific. They are only recognized by specific tissues.

Positive Feedback Increase levels of a hormone trigger the release of even more hormone. –Examples: childbirth and lactation

Negative Feedback An increase will trigger a decrease… Low blood sugar Eat food High blood sugar Insulin released from Pancreas

Hypersecretion: too much hormone is secreted. Hyposecretion: too little hormone is secreted.

Pituitary Gland Location: In the brain Hormones: Many… growth hormone, thyroid secreting hormone…. Effects: Controls the secretions of other glands

Hypothalamus Location: in brain Hormones: oxytocin and ADH Effects: childbirth contractions and water retention.

Thyroid: Location: neck Hormones: Thyroxine Effect: controls metabolism

Parathyroid Location: behind thyroid gland Hormone: parathormone Effect: increases blood calcium

Adrenal Glands Location: on top of kidneys Hormones: Adrenalin, etc. Effect: Fight or flight response

Pancreas Location: below stomach Hormones: Insulin, glucagon Effect: decrease or increase blood sugar levels

Gonads= testes or ovaries Location: lower abdomen Hormones: Testosterone or Estrogen Effect: development and reproduction

Thymus Location: above heart Hormones: Thymopoeiten Effect: development of immune system

Pineal Gland Location: Brain Hormones: Melatonin Effect: Day/night cycles