REGULATION

CHEMICAL REGULATION –CHAPTER 16

Chemical vs Nervous Regulation

Body systems never rest – make constant adjustments to maintain homeostasis Nervous system and endocrine system Endocrine system releases chemicals into the

blood stream and regulates metabolism, growth, reproduction

Chemical regulation is slower than impulse regulation

Chemical regulation results lasts longer than nervous regulation

Glands

Glands are made of epithelial cells that secrete substances needed by the body

Exocrine glands have ducts that carry secretions to where they are needed

Endocrine glands (ductless glands) secrete directly into the blood stream Make up the endocrine system Secrete hormones that travel in the blood stream Controls homeostasis, metabolism, growth,

reproduction

Exocrine glands have ducts that carry secretions to where they are needed

Endocrine glands (ductless glands) secrete directly into the blood stream

Hormones

Chemical messengers – where secreted is not where it is used

Target tissue is the specific tissue that recognizes a specific hormone

Hormone stimulates target tissue to increase, decrease, stop or start activities Hormones do not act directly on the target

tissue but change a cellular process that affects the target tissue

Target tissue is the specific tissue that recognizes a specific hormone

Hormone stimulates target tissue to increase, decrease, stop or start activities

Hormones

Two types of hormones

Protein type (made of amino acids) cannot pass through the cell membrane (ex: insulin)

Steroid type (lipid-like) can pass through the cell membrane (ie: estrogen)

Hormones

Protein type (made of amino acids) cannot pass through the cell membrane (ex: insulin)

Hormones

Steroid type (lipid-like) can pass through the cell membrane (ie: estrogen)

The Regulation of Hormones

The rate of secretion varies with the needs of the body

Chemical stimulation regulates secretions and overlaps with the nervous system

Chemical regulation is accomplished by feedback Positive feedback – reinforces the original change Negative feedback – opposes the original change Negative feedback usually maintains homeostasis

Mechanisms of Hormone Action

Hormones are in the blood and enter all organs but are only recognized by the target tissues

HOW?

One-messenger Model

Steroid hormones Enters all cells of the

body but only the target tissue has receptor proteins that react with the hormone and form an active factor. The active factor produces the hormone effect.

Two-messenger Model

Protein-type hormones

Cannot pass through the cell membrane – specific receptors on the outer surface of the target cell membranes that react and activate enzymes in the membranes that act as a second messenger.

Add the following table to the bottom of page 20 in your

packet

Compare Chemical Regulation vs Nervous Regulation

Chemical Regulation Nervous Regulation

Both systems work together to maintain homeostasis

Reacts more slowly Reacts more quickly

Effects last longer Effects are short term

Chemical messengersElectrochemical

messengersMessengers (hormones) travel all over the body in

the blood (circulation)

Messengers are directed to a specific

area (nerve pathways)

Turn to the diagram on page 26 in your packet

HUMAN ENDOCRINEPineal

Testes

Pancreas

Adrenals

Thymus

Parathyroids

Thyroid

Pituitary

Hypothalamus

Ovary

Turn to page 28 in your packetFollow along with the notes

Pituitary Gland Known as the Master Gland Controls the release of

hormones from many other endocrine glands

Connected to the hypothalamus which Controls the release of

hormones from the pituitary Receives information from the

nervous system Stimulates the pituitary to

release hormones

ANTERIOR PITUITARY

1. Thyroid-stimulating hormone (TSH) Stimulates the production and release of thyroxin from the

thyroid2. Adrenocorticotropic hormone (ACTH)

Stimulates the production and release of hormones from the adrenal glands

3. Growth hormone (GH) Indirectly affects bone and cartilage growth Directly affects cellular metabolism

4. Follicle-stimulating hormone (FSH) Stimulates development of eggs (female – ovaries) Stimulates production of sperm (males – testes)

5. Luteinizing hormone (LH) Stimulates the release of eggs from the ovaries Controls production of sex hormones in males and females

6. Prolactin Stimulates secretion of milk after child birth

POSTERIOR PITUITARY

1. Connected to the hypothalamus

2. Oxytocis Stimulates contraction of the uterus

during child birth

3. VasopressinControls reabsorption of water by the

nephrons in the kidneys

THYROID

Located under the larynx –

in front of the trachea Thyroxin

Regulates the rate of metabolism

Calcitonin Regulates the blood’s calcium

level

PARATHYROID GLANDS

Four tiny glands in the back of the thyroid

1. Parathyroid hormone Regulates calcium and

phosphate metabolism hypersecretion –

removes Ca from the bones – osteoporosis

hyposecretion – lowers the blood’s Ca level – tetany

THE ADRENAL GLANDS

Located on the kidneys Helps the body deal with stress (fight or flight

response)

THE ADRENAL GLANDS

Adrenal medulla (inner layer of the adrenal gland) Epinephrine or adrenalin (80%) Norepinepherine or noradrenalin (20%)

Regulates the fight or flight response Responds to fear, anger, pain, exertion Causes increased rate of metabolism and

increased release of glucose (increases heart rate, blood pressure, breathing rate, blood clotting, and sweating)

THE ADRENAL GLANDS

Adrenal cortex (outer layer of the adrenal gland)

1. Cortisol Controls metabolism of carbohydrates,

proteins, and fats

2. Cortisone Counteracts allergies

3. Aldosterone Regulates mineral balance in the blood

PANCREAS

Is both an exocrine and endocrine gland!!

PANCREAS

Exocrine Secretes digestive juices through the

pancreatic duct to the small intestines

PANCREAS

Endocrine –secretions from the islets of Langerhans

1. Alpha cells Secretes glucagon Raises the blood sugar (glucose) levels

2. Beta cells Secretes insulin Lowers blood sugar (glucose) levels

When the islets of Langerhans fail to produce insulin – diabetes mellitus results

THE GONADS (sex glands)

Ovaries (female)

1. Estrogen Stimulates the development

of female reproduction system

Stimulates the development of secondary female sex characteristics

2. Progesterone Regulates female menstrual

cycle

THE GONADS (sex glands)

Testes (male)

1. Testosterone Stimulates the development

of male reproduction system

Stimulates the development of secondary male sex characteristics

Turn to page 22 in your packet

What is Regulation?

All the activities that help maintain an organism’s homeostasis

Compare Nervous System vs Endocrine System

The nervous system: Responds quickly Short lasting

The endocrine system: Responds more slowly Longer lasting

Compare Endocrine Glands vs Exocrine System

Endocrine glands (ductless glands) secrete hormones which travel to target

tissues through the blood examples = ovaries, thyroid

Exocrine glands have ducts or tubes that carry secretions to

the target organ example = digestive glands (pancreas)

Compare Two Types of Hormones

Steroid small and lipid-like can pass through the cell membrane example = estrogen one messenger model

enters many cells effects only cells with specific receptor

proteins

Compare Two Types of Hormones

Protein-type made of amino acids – large molecules cannot pass through the cell membrane example = insulin two messenger model

target cells have receptor proteins on the cell membrane surface

hormone and receptor combine – release enzyme into the cell that acts as a second messenger

Check out the diagrams on page 23B in your packet

(one and two messenger models)

Check out the diagram on page 23A in your packet

(positive and negative feedback)

Regulation of Hormone Secretion

Feedback = the level of one hormone inhibits or stimulates the production of another hormone

1. Positive feedback = reinforces the original change

2. Negative feedback = opposes the original change

Turn to page 27 in your packet

Turn to page 29 in your packet

RECEIVES SENSORY INPUT RECEIVES SENSORY INPUT

HYPOTHALAMUS

•Part of the brain•Receives sensory input

•Controls the release of hormones in the pituitary (releasing factors)

PITUTARY GLAND “Master Gland”

secretes secretes TSH ACTH

(thyrotrophic stimulating hormone) (adrenocorticotrophic hormone)

secretes cortisol

(controls the metabolism of carbohydrates, proteins, and

fats)

ADRENAL CORTEX

•An increased rate of metabolism will inhibit the hypothalamus

•An decreased rate of metabolism will stimulate the hypothalamus

THYROID

secretes thyroxin(controls the rate of metabolism)

Endocrine Disorders and Diseases

Anterior PituitaryGrowth Hormone

HYPERSECRETION HYPOSECRETION

Gigantism (child onset)Body proportional

Dwarfism (body proportional)

Acromegaly (adult onset)Enlarged hands, feet and facial features

Gigantism (child onset)Body proportional

Anterior Pituitary - Growth HormoneHYPERSECRETION

Acromegaly (adult onset)Enlarged hands, feet and facial features

Anterior Pituitary - Growth HormoneHYPERSECRETION

Dwarfism (body proportional)

Anterior Pituitary - Growth HormoneHYPOSECRETION

Adrenal Cortexcortisol (controls metabolism)

HYPERSECRETION HYPOSECRETION

Cushing’s Disease Fat deposits upper body, puffy

face, excess facial hair

Addison’s DiseaseSluggish, weight loss, weakness

John F. Kennedy had Addison‘s Disease

Thyroidthyroxin (rate of metabolism)

HYPERSECRETION HYPOSECRETION

HyperthyroidismNervous, irritable, eyes may

protrude

HypothyroidismADULT onset: Sluggish, tired, weight gainCHILD onset: cretinism – dwarfism (body not proportional) and mental retardation

Thyroid

Thyroxin contains iodine Deficiency of iodine causes a goiter

Pancreassecretes insulin for glucose metabolism

HYPERSECRETION HYPOSECRETIONDiabetic Shock

Cold sweat, confusion, In extreme cases:

unconsciousness, coma, death

Uncontrolled diabetesDehydration, weight loss, thirst,

irritability

Remember: the pancreas is both an exocrine gland (digestive juices) and an endocrine gland (insulin and glucagon for controlling blood sugar levels.

Review the answers to the worksheets on pages 24-25 in your

packet

Please turn to page 21 in your packet

Did you know that plants have hormones, too?

Plant Hormones Chemical messengers Produced in tips of roots and stems (meristem region) Three kinds1. Auxins = hormones that affect growth

Stimulate or slow growth Cause cells to lengthen and differentiate Affects abscission (dropping off of leaves, fruit,

flowers)2. Gibberellins

Distributed evenly through out the plant tissue Affects stem growth and fruit size

3. Cytokinins stimulate cell division and growth during seed

germination

Auxins and Tropism

Tropism = growth of a plant in a specific direction in response to a stimulus Toward the stimulus – positive

tropism Away from the stimulus – negative

tropism Kinds of tropism

phototropism = light geotropism = gravity thigmotropism = touch hydrotropism = water

Nastic Movements

Plant movement in response to a stimulus, but independent of the direction of the stimulus Prayer plant – leaves

collapse due to loss of turgor (water pressure)

Venus fly trap

Photoperiodism

Response of a plant in response to changes in the length of a day

Not time of light that determines flowering, but the number of dark hours1) Short-day (long night) plants bloom in spring,

late summer2) Long-day (short night) plants bloom in summer3) Day-neutral plants are not affected by light

hours Affected by pigment phytochrome