Endocrine and Nervous SystemsMaintaining Homeostasis…. Together…

Endocrine SystemYAY HORMONES!

Primary Mission: Controlling the activity of other body systems through chemicals.

Endocrine Glands• Secrete hormones• Hormone• A chemical made in one part of the body that affects

another part of the body.• Circulate through blood or lymph• Act only on specific organs or tissues

Types of Endocrine Glands• Some important examples:• Hypothalamus: regulates pituitary

gland• Pituitary gland: controls other

endocrine glands• Pancreas: Produces Insulin and

glucagon to regulate glucose levels.• Adrenal Glands: regulate metabolism

and adjust to stress in the body• Pineal Gland: Regulate rhythmic

cycles (like heartbeat)• Ovaries and Testes: Release

reproductive hormones• Thyroid: regulates metabolism• Thymus: Regulates immune

responses

How Hormones Work…

Regulating Hormones• Negative

Feedback• A process in which a

change in the environment causes a response that returns conditions to their original status.

Example.…When you are hot or exercise strenuously, you lose water through sweat. If you lose too much water, your pituitary gland releases a hormone called ADH. Your blood carries the ADH to your kidneys, where it signals the kidneys to slow the removal of water from the blood. You also feel thirsty and take a drink of water. When the water level in your body rise, the pituitary slows down and the production of ADH. The kidneys increase the amount of water removed from the blood, restoring your original water levels.

Discuss…• How do you think your pituitary gland would

respond if the water level in your blood remained lower than normal? Why might this happen?

Question 1The endocrine system is made up of glands that

A. Secrete enzymes that help to digest food.B. Carry oxygen to all parts of the body.C. Secrete hormones directly into the bloodstream.D. Carry nerve impulses from one part of the body to

another.

Question 2What is homeostasis?A. The ability of an organism to maintain a

relatively stable internal environmentB. The production of a hormone by an endocrine

gland that works on another endocrine glandC. A series of events that monitor how hormones

work in the bodyD. A process in which a change in the environment

causes a response that returns conditions to their original status

Question 3Which is the correct sequence of steps in the negative feedback system that adjusts your body temperature in a cold environment?A. Hypothalamus– pituitary gland—thyroid gland–

metabolism increasesB. Pituitary gland– metabolism increases–

hypothalamus– thyroid glandC. Thyroid gland—thyroxine—pituitary gland–

metabolism increasesD. Pituitary gland—thyroxine—thyroid gland–

hypothalamus—metabolism increases

Nervous SystemReacting to the World…

Controls and coordinates body activities, including responses to internal and external stimuli

Stimulus—Response• Stimulus• Any condition in the environment that produces a reaction• Light, temperature, movement, pressure, chemicals,

and sound• Response• An organism’s reaction to a stimulus• Endocrine Glands: chemical response (hormones)• Nervous System: Electrochemical response

Two parts….• Central Nervous

System• Brain and Spinal

Cord• Relays messages• Processes

information• Analyzes

information• Receives and

Sends nerve impulses to and from body parts.

• Peripheral Nervous System• Nerves that are

not part of the brain or spinal cord• Somatic Nervous

system• Regulates

conscious activities• Autonomic

Nervous system• Regulates

involuntary activities

Neurons

Types of NeuronsSensory

• Carry impulses from the sense organs to the spinal cord and brain

Motor• Carry impulses from

the brain and spinal cord to the muscles and glands.

• Carry impulses between sensory and motor neurons

Interneurons

Nerve ImpulsesNerve

Impulse

Neuron Communication

Sense Organs

Discuss..• Both the nervous and endocrine systems may

respond to certain stimuli. An example is the response of your body to cold outdoor temperatures. Describe how both the nervous system and the endocrine system might respond to a sudden drop in temperature.

Question 1Which of the following BEST describes the role of the nervous system?A. Responds to all internal and external stimuliB. Detects only stimuli from outside an organismC. Responds only to stimuli occurring inside an

organismsD. Detects internal and external stimuli at the

cellular level

Question 2Which of the following are cells of the nervous system?A. SynapsesB. Potassium ionsC. Protein channelsD. neurons

Question 3Involuntary body activities are controlled by theA. Somatic nervous systemB. Autonomic nervous systemC. Sensory receptorsD. interneurons

Question 4The role of motor neurons is toA. Carry impulses from the sense organs to the

spinal cord and brain.B. Carry impulses from the brain and spinal cord to

muscles and glands.C. Carry hormones from an endocrine gland to its

target organ.D. Carry impulses between sensory neurons and

endocrine glands.