9b. Know how the nervous system mediates communication between different parts of the body and the body’s interaction with the environment.

9b. Know how the nervous system mediates communication

between different parts of the body and the body’s interaction

with the environment.

9c. Know how feedback loops in the nervous and endocrine systems regulate conditions in

the body.

*9i. Know how hormones (including digestive, reproductive, osmoregulatory) provide internal

feedback mechanisms for homeostasis at the cellular level

and in whole organisms.

Standard 9b & 9c Vocabulary

• Feedback Loops• Endocrine System• Negative Feedback• Regulation• Potassium Ion• Sodium Ion• Channel Ions• Impulse

• Neuron• Interneuron• Sensory Neuron• Motor Neuron• Brain• Reflex• Stimuli• Gray Matter• White Matter

Organization of the Body

• ___________ System• Structures: Brain,

spinal cord, peripheral nerves

• Function: Recognizes and _____________ the body’s response to changes in its internal and external environments

Organization of the Body• ______________

System• Structures:

Hypothalamus, pituitary, thyroid, parathyroid, adrenals, pancreas, ovaries (in females), testes (in males)

• Function: Controls growth, development and metabolism; maintains ________________

35-2 The Nervous System

– What are the functions of the nervous system?• The nervous system controls and coordinates functions

throughout the body and responds to _______________ & _____________ stimuli.

• Neurons• The messages carried by the nervous system are electrical

signals called impulses. • The cells that transmit these impulses are called

____________________.

Neurons

• Neurons are classified according to the direction in which an impulse travels.

• ________________ neurons carry impulses from the sense organs to the spinal cord and brain.

• _____________ neurons carry impulses from the brain and spinal cord to muscles and glands.

• __________________ connect sensory and motor neurons and carry impulses between them.

Neurons

• Structures of a Neuron

Axon terminals

Myelin sheath

Cell body

Nodes Axon

Dendrites

Nucleus

Neurons

• The largest part of a typical neuron is the _________ __________.

• It contains the nucleus and much of the cytoplasm.

Cell body

Neurons

• _____________ extend from the cell body and carry impulses from the environment toward the cell body. Dendrites

Neurons

• The __________ is the long fiber that carries impulses away from the cell body.

Axon terminals

Axon

Neurons

• The axon ends in axon _______________.

Axon terminals

Axon

Neurons

• The axon is sometimes surrounded by an insulating membrane called the __________ _______________.

• There are gaps in the myelin sheath, called nodes, where the membrane is exposed.

• ____________ jump from one node to the next.

Myelin sheath

Nodes

39-1 The Endocrine System

– What is the function of the endocrine system?

• The endocrine system is made up of _____________ that release their products into the bloodstream. These products deliver messages throughout the body.

• The _______________ released by the endocrine system can affect almost every cell in the body.

Hormones

• Hormones• ____________________ are chemicals released in one part

of the body that travel through the bloodstream and affect the activities of cells in other parts of the body.

• Hormones bind to specific chemical receptors on cells.

• Cells that have receptors for a particular hormone are called _______________ _______________.

• If a cell does not have ________________ or the receptors do not respond to a hormone, that hormone has no effect on it.

Glands

• Glands• A gland is an organ that produces and releases a

secretion. There are two kinds of glands:• ________________ glands release secretions

through ducts directly to the organs that use them. • ________________ glands release their

secretions directly into the bloodstream.

Glands

•Hypothalamus •The hypothalamus makes hormones that control the ____________ gland. In addition, the hypothalamus makes hormones that are stored in the pituitary gland.

GlandsPituitary gland

The pituitary gland produces hormones that regulate ________ of the other endocrine glands.

Glands

• Parathyroid glands

• The parathyroid glands release parathyroid hormone, which regulates the level of ___________ in the blood.

Glands

• Thymus

• During childhood, the thymus releases thymosin, which stimulates ________ development and proper immune response.

Glands

• Adrenal glands• The adrenal glands

release ______________ and norepinephrine, which help the body respond to stress.

Glands

• Testis

• The testes produce ________________, which is responsible for sperm production and the development of male secondary sex characteristics.

Glands• Ovary • Ovaries produce estrogen

and progesterone. ____________ is required for the development of female secondary sex characteristics and for the development of eggs. Progesterone prepares the uterus for a fertilized egg.

Glands

• Pancreas

• The pancreas produces ____________ and glucagon, which regulate the level of _______________ in the blood.

Glands

• Thyroid

• The thyroid produces thyroxine, which regulates ______________ throughout the body.

Glands

• Pineal gland

• The pineal gland releases _____________, which is involved in rhythmic activities, such as daily sleep-wake cycles.

Hormone Action

• Hormone Action• Hormones are classified as either

______________ or nonsteroids. • Steroid hormones are produced from a lipid called

_____________________.• Nonsteroid hormones include proteins, small

peptides, and modified amino acids.

Control of the Endocrine System

• Control of the Endocrine System– How does the endocrine system maintain

homeostasis?• The endocrine system is regulated by feedback

mechanisms that function to maintain ____________________.

Control of the Endocrine System

– Example: Controlling Metabolism• Thyroxine, a hormone of the thyroid gland, affects

the activity of cells throughout the body, increasing their rate of metabolism.

• A drop in thyroxine decreases the metabolic activity of cells.

Control of the Endocrine System

• If _______________ is low, the hypothalamus secretes thyrotropin-releasing hormone (TRH), which stimulates the anterior pituitary to secrete thyroid-stimulating hormone (TSH).

• TSH stimulates the release of thyroxine.

• High levels of thyroxine in the blood inhibit secretion of _______ & _________, which stops the release of additional thyroxine.

Control of the Endocrine System

• Controlling Metabolism

Control of the Endocrine System• The hypothalamus is also sensitive to

________________.• If body temperature drops, it produces extra TRH. • TSH is released, which causes the release of

more thyroxine. • Thyroxine increases _____________

consumption and cellular metabolism. • Increased metabolic activity maintains a core

temperature.

Complementary Hormone Action

• Complementary Hormone Action• Sometimes two hormones with opposite effects act to

regulate part of the body’s internal environment.• Such a complementary system regulates the level of calcium

ions in the bloodstream.

• Two hormones that regulate calcium concentration are calcitonin and parathyroid hormone (______).

• Calcitonin decreases the level of ___________ in the blood, while PTH increases it.

Complementary Hormone Action

• If calcium levels are too high, the thyroid secretes calcitonin.

• Calcitonin signals the ____________ to reabsorb less calcium.

• Calcitonin also reduces the amount of calcium absorbed in the intestines and stimulates calcium deposition in the bones.

Complementary Hormone Action

• If calcium levels drop too low, PTH is released by the parathyroids.

• PTH, with _________________, stimulates the intestine to absorb more calcium from food.

• PTH also causes the kidneys to retain calcium, and it stimulates bone cells to release calcium stored in bone tissue into the bloodstream.

39-2 Human Endocrine Glands

• The endocrine glands are scattered throughout the body.

• The human endocrine system regulates a variety of ______________.

• Any improper functioning of an endocrine gland may result in a disease or a disorder.

Pituitary Gland

• Pituitary Gland– What is the function of the pituitary gland?

• The pituitary gland secretes nine hormones that directly regulate many body functions and controls the actions of several other endocrine glands.

– The _______________ ________ is a structure at the base of the skull.

– The gland is divided into two parts: the anterior pituitary and the posterior pituitary.

Pituitary Gland• The Pituitary Gland

Hypothalamus

Pituitary gland

Posterior pituitary

Anterior pituitary

Hypothalamus

• Hypothalamus– What is the function of the hypothalamus?

• The hypothalamus is the part of the _________ attached to the posterior pituitary.

• The hypothalamus controls the secretions of the pituitary gland.

HypothalamusHypothalamus

Pituitary gland

Hypothalamus

• The hypothalamus is influenced by hormone levels in the ___________ and by sensory information.

• Interactions between the nervous system and the endocrine system take place at the hypothalamus.

• The close connection between the hypothalamus and the pituitary gland means that the nervous and endocrine systems act together to coordinate body activities.

Adrenal Glands

• Adrenal Glands– What is the function of the adrenal glands?

• The adrenal glands are two pyramid-shaped structures that sit on top of the kidneys, one gland on each kidney.

• The adrenal glands release hormones that help the body prepare for and deal with _______________.

Adrenal GlandsAdrenal gland

Kidney

Adrenal Glands

• An adrenal gland has an outer part called the ___________ ____________ and an inner part called the adrenal medulla.

Adrenal cortex

Adrenal medulla

Adrenal Glands

– Adrenal Cortex• The adrenal cortex produces over 24 steroid

hormones. • The hormone aldosterone regulates

_______________ of sodium ions and the excretion of potassium ions by the kidneys.

• The hormone cortisol controls the rate of metabolism of __________________, _________, _________________ & _________________.

Adrenal Glands

– Adrenal Medulla• The release of hormones from the adrenal medulla prepares

the body for __________-_________ activities.• The two hormones released by the adrenal medulla are

epinephrine and norepinephrine.

• Epinephrine and norepinephrine:• increase heart rate, blood pressure, and blood flow to the

muscles.• cause air passageways to open wider, allowing for an

increased intake of oxygen.• stimulate the release of extra glucose into the blood to help

produce a sudden burst of energy.

Pancreas

• Pancreas– What is the function of the pancreas?

• The pancreas has both exocrine and endocrine functions.

• It is a digestive gland whose secretions break down food.

• It produces insulin and glucagon.» Insulin and glucagon help to keep the level of

________________ in the blood stable.

Pancreas

• Insulin stimulates cells in the ___________ and muscles to remove sugar from the blood and store it as glycogen or fat.

• _______________ stimulates the liver to break down glycogen and release glucose back into the blood.

Pancreas– Maintaining Blood Sugar Levels

• When glucose levels rise, the pancreas releases insulin. • Insulin stimulates cells to take glucose out of the

bloodstream.

– _____________ taken out of circulation is stored as _______________ in the liver and skeletal muscles.

– In fat tissue, glucose is converted to lipids.– When blood glucose level drops, glucagon is released

from the pancreas.

Pancreas

• Glucagon stimulates liver cells and skeletal muscles to break down glycogen and increase glucose levels.

• It causes fat cells to break down fats for production of carbohydrates.

• This makes more chemical _____________ available and helps raise the blood glucose level back to normal.

Summary

• Organisms maintain a constant internal environment, even when conditions outside the body change. The nervous system _______________ body conditions, such as temperature, and signals endocrine glands, such as the hypothalamus, to release chemicals that help keep _________ conditions constant.

Summary

• Hormones are chemicals that are released in one part of the body and affect another part of the body. Hormones control body conditions such as temperature, and thus they help organisms maintain a constant internal environment. Feedback mechanisms work to regulate the activity of the body and help maintain homeostasis.