Maintaining Homeostasis…. Together…

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

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

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

Negative Feedback A process in which a change in the environment causes a response that returns conditions to their original status.

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.

How do you think your pituitary gland would respond if the water level in your blood remained lower than normal? Why might this happen?

The 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.

What is homeostasis? A.The ability of an organism to maintain a relatively stable internal environment B.The production of a hormone by an endocrine gland that works on another endocrine gland C.A series of events that monitor how hormones work in the body D.A process in which a change in the environment causes a response that returns conditions to their original status

Which 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 increases B.Pituitary gland– metabolism increases– hypothalamus– thyroid gland C.Thyroid gland—thyroxine—pituitary gland– metabolism increases D.Pituitary gland—thyroxine—thyroid gland– hypothalamus— metabolism increases

Reacting to the World… Controls and coordinates body activities, including responses to internal and external stimuli

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

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

Sensory 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 Impulse Neuron Communication

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.

Which of the following BEST describes the role of the nervous system? A.Responds to all internal and external stimuli B.Detects only stimuli from outside an organism C.Responds only to stimuli occurring inside an organisms D.Detects internal and external stimuli at the cellular level

Which of the following are cells of the nervous system? A.Synapses B.Potassium ions C.Protein channels D.neurons

Involuntary body activities are controlled by the A.Somatic nervous system B.Autonomic nervous system C.Sensory receptors D.interneurons

The role of motor neurons is to A.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.