The Nervous & Endocrine System

How our body’s communication system maintains homeostasis

Chapter 29

The Division of the Nervous System

Brain and spinal cord

Receives stimuli and coordinates response

Motor neurons, carry impulse to muscles and glands

Body to the CNS

Displays response to organs and glands

Sensory neuron carries impulse from sense organs to CNS

Divided into

Sensory

Motor

Somatic –conscious control

Autonomic - involuntary

Central Nervous System Peripheral Nervous System

Three types of NeuronsNeuron = Nerve cell

• Sensory Neuron- carries nerve impulse from sense organs to brain and spinal cord, PNS to CNS

• Motor Neuron- Carries nerve impulse from the brain and spinal cord to the muscles and glands, CNS to PNS

• Interneurons- connect sensory neurons with motor neurons and carry nerve impulses between them

How an external stimuli becomes a response

Neuron PhysiologyCell body- where most metabolic activities take place

Dendrites- receive nerve impulse and transmit to cell body

Axon- carries nerve impulse away from cell body

Myelin sheath- covers axon, acts as a insulator for electrochemical impulses

Nodes- gaps in the myelin sheath, nerve impulse jumps from node to node

Synapse- area where one neuron transfers impulse to an adjacent neuron

Nerve ImpulseAll or None Principle

Neurotransmitters (chemicals) are released from the axon and transmit impulse across synapse by binding to receptor sites on dendrite of adjacent neuron

Impulses are self-propagating, like dominos

Endocrine System

Made up of glands that release their products into the

bloodstream.

These hormones broadcast These hormones broadcast

chemical messages chemical messages

throughout the bodythroughout the body

REFLEX ARC

•Immediate response from our body due to a painful stimulus

• Faster reaction time due to the initial bypass of the brain.

•Nerve impulse takes a shorter route through the nervous systemReceptor → Sensory Neuron → Spinal Cord → Motor Neuron → Effector

The Endocrine system is regulated by feedback mechanisms

that function to maintain homeostasis

The body’s response

to a hormone is slow,

several minutes to several days

Major Glands

Pituitary

Thyroid

Adrenal

Pancreas

Gonad

The major glands

Pituitary Thyroid Pancreas Adrenal Gonad

Gets direction from hypothalamus

Metabolism

Calcium level

Blood glucose level

Fight or flight syndrome

Reproduction and sex characteristics

GH

ADH

FSH

TSH

T3

T4Calcitonin

Insulin Glucagon

Epinephrine Estrogen

Androgen

Progesterone

Negative Feedback Mechanism of Blood Glucose,

Glucagon, and Insulin