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Home , Endocrine system, Tropic hormone

Chapter 45- and the Pathway Example – Simple Pathways Low pH in

•Hormones are released from an endocrine cell, S cells of duodenum travel through the bloodstream, and interact with secrete ( ) Endocrine the or a target cell to cause a physiological cell response Blood vessel A negative loop

Target cells

Response release

Insulin and : Control of Blood Body cells • and glucagon are take up more Insulin antagonistic hormones that help glucose. maintain glucose homeostasis Beta cells of pancreas release insulin into the blood. The pancreas has clusters of endocrine cells called takes islets of Langerhans up glucose and stores it as glycogen. STIMULUS: Blood glucose Blood glucose level level declines. rises.

Target Tissues for Insulin and Glucagon Homeostasis: Blood glucose level Insulin reduces blood glucose levels by: (about 90 mg/100 mL)

Promoting the cellular uptake of glucose

Blood glucose STIMULUS: Slowing glycogen breakdown in the liver level rises. Blood glucose level falls.

Promoting fat storage

Alpha cells of pancreas release glucagon. Liver breaks down glycogen and releases glucose. Glucagon

Glucagon increases blood glucose levels by:

Stimulating conversion of glycogen to glucose in the liver

Stimulating breakdown of fat and into glucose Mellitus

Type I diabetes mellitus (insulin-dependent) is an autoimmune disorder in which the destroys pancreatic beta cells

Type II diabetes mellitus (non-insulin-dependent) involves insulin deficiency or reduced response of target cells due to change in insulin receptors

The endocrine and nervous systems act individually and together in regulating

•Signals from the initiate and regulate endocrine signals

The receives Cerebrum information from the nervous system and initiates responses through the Pineal endocrine system Hypothalamus Cerebellum

Attached to the hypothalamus is the pituitary gland composed of the and

Hypothalamus The posterior pituitary Posterior pituitary Anterior The anterior pituitary pituitary

Posterior Pituitary Hormones Hypothalamus

•The two hormones released from the posterior pituitary act directly on nonendocrine tissues

Neurosecretory cells of the Axon hypothalamus

Posterior pituitary

Anterior pituitary

HORMONE ADH Oxytocin

TARGET tubules Mammary , uterine muscles

•This is an example of positive feedback, where the stimulus leads to an even greater response Pathway Example Stimulus Suckling +

Sensory •Suckling sends a message to the hypothalamus via the Hypothalamus/ nervous system to release oxytocin, which further posterior pituitary

stimulates the milk glands. Neurosecretory cell Posterior pituitary Blood secretes oxytocin ( )

vessel Positive Positive feedback

Target Smooth muscle in cells

Response Milk release

Antidiuretic hormone (ADH) or vassopressin Anterior Pituitary Hormones Tropic effects only: FSH Neurosecretory cells LH of the hypothalamus TSH •Hormone production in the anterior ACTH pituitary is controlled by releasing and Nontropic effects only: inhibiting hormones from the MSH hypothalamus Nontropic and tropic effects: GH Hypothalamic Portal vessels releasing and inhibiting hormones Endocrine cells of Posterior pituitary the anterior pituitary Pituitary hormones

HORMONE FSH and LH TSH ACTH Prolactin MSH GH

TARGET Testes or Adrenal Mammary Melanocytes Liver, , cortex glands other tissues

For example, the production of thyrotropin releasing hormone (TRH) in the hypothalamus Pathway Example

Stimulus Cold

Sensory neuron – Hypothalamus secretes thyrotropin-releasing hormone (TRH ) Neurosecretory cell

Blood vessel Hormone Cascade Pathways

•A hormone can stimulate the release of a series of – Anterior pituitary secretes other hormones, the last of which activates a thyroid-stimulating nonendocrine target cell; this is called a hormone hormone (TSH cascade pathway or thyrotropin )

Negative Thyroid gland secretes thyroid hormone (T and T ) The release of thyroid hormone results from a 3 4 hormone cascade pathway involving the hypothalamus, anterior pituitary, and thyroid gland.

Target Body tissues cells

Increased cellular Response

•Hormone cascade pathways are usually regulated by negative feedback Tropic Hormones Tropic effects only: FSH Neurosecretory cells LH of the hypothalamus A TSH ACTH Nontropic effects only: The four strictly tropic hormones are Prolactin MSH

Nontropic and tropic effects: Thyroid-stimulating hormone (TSH) GH Hypothalamic Portal vessels releasing and inhibiting hormones Follicle-stimulating hormone (FSH) Endocrine cells of Posterior pituitary the anterior pituitary (LH) Pituitary hormones

Adrenocorticotropic hormone (ACTH) HORMONE FSH and LH TSH ACTH Prolactin MSH GH

•Follicle-stimulating hormone (FSH) and TARGET Testes or Thyroid Adrenal Mammary Melanocytes Liver, bones, Luteinizing hormone (LH) ovaries cortex glands other tissues Stimulate the activities of the male and female , the testes and the ovaries, respectively.

Adrenocorticotropic hormone (ACTH) -stimulates the production and secretion of hormones by the .

Nontropic Hormones

•Nontropic hormones produced by the anterior pituitary are: Prolactin (PRL)

Melanocyte-stimulating hormone (MSH)

Prolactin stimulates in mammals but has diverse effects in different

-regulates fat metabolism and in birds

-delays metamorphosis in

-regulates salt and water balance in freshwater

MSH influences skin pigmentation in some vertebrates and fat metabolism in mammals

Growth Hormone • (GH) is secreted by the anterior pituitary gland and has tropic and nontropic actions It promotes growth directly and has diverse metabolic effects Robert Wadlow

Warwick Davis http://en.wikipedia.org/wiki/Dwarfism Endocrine glands respond to diverse stimuli in regulating metabolism, homeostasis, development, and behavior

•Endocrine signaling regulates metabolism, homeostasis, development, and behavior Thyroid Hormone: Control of Metabolism and Development

• stimulate metabolism and influence development and maturation

http://en.wikipedia.org/wiki/Thyroid

triiodothyronine (T3)

http://en.wikipedia.org/wiki/Image:Triiodothyronine.svg

http://en.wikipedia.org/wiki/Thyroid

thyroxine (T4)

http://en.wikipedia.org/wiki/Image:Thyroxine-2D-skeletal.png It produces two iodine-containing hormones: triiodothyronine (T3) and thyroxine (T4)

Hyperthyroidism,

Hyperthyroidism, excessive secretion of thyroid hormones,

•Graves’ disease is a form of hyperthyroidism in

Hypothyroidism •Proper thyroid function requires dietary iodine for hormone production

Iodine deficiency in the diet and : Control of Blood Two antagonistic hormones regulate the homeostasis of calcium (Ca 2+) in the blood of mammals

Calcitonin Parathyroid hormone (PTH) Thyroid gland releases . Reduces Calcitonin Stimulates Ca2+ uptake Ca2+ deposition in kidneys in bones

2+ PTH increases the level of blood Ca2+ STIMULUS: Blood Ca Rising blood level declines Ca2+ level to set point

2+ It releases Ca from and Homoeostasis: stimulates of Ca2+ in Blood Ca2+ level the kidneys (about 10 mg/100 mL) Blood Ca2+ STIMULUS: level rises Falling blood to set point Ca2+ level It also has an indirect effect, stimulating Stimulates Parathyroid the kidneys to activate vitamin D, which Ca2+ release gland promotes intestinal uptake of Ca2+ from from bones food. PTH

Increases Ca2+ uptake 2+ in intestines Active Stimulates Ca vitamin D uptake in kidneys

•Calcitonin decreases the level of blood Ca2+ It stimulates Ca2+ deposition in bones and secretion by kidneys.

Study outline-Chapter 45- Hormones and the Endocrine System Understand simple hormone pathways and negative feedback Ex: insulin and glucagon: control of blood glucose Differentiate between Type I diabetes mellitus (insulin-dependent) and Type II diabetes mellitus (non-insulin dependent) Understand the coordination of endocrine and nervous systems in vertebrates -How is the hypothalmus involved? How are the posterior and anterior pituitary involved? What 2 hormones are released from the posterior pituitary that act directly on nonendrocrine ?

Understand the process of positive feedback. Ex: oxytocin

What are the functions of antidiuretic hormone (ADH)? Understand the hormone cascade pathway Differentiate between tropic and nontropic hormones. -Name the 4 tropic hormones and their functions. -Name the 2 tropic hormones and their functions.

What is the function of growth hormone (GH)? Differentiate between and dwarfism. Understand thyroid hormone. -Name the two iodine-containing hormones. -Differentiate between hyperthyroidism and . Understand how the parathyroid hormone and vitamin D control blood calcium Give examples of multiple effects of hormones.

Name the different types of local regulators and their functions. Pathway Example

– Stimulus Low pH in Describe the general structure of a hormone pathway using the duodenum figure provided.

Using the same figure, explain the concept of negative feedback. S cells of duodenum secrete secretin ( )

Endocrine cell

Blood vessel

Target Pancreas cells

Response Bicarbonate release

Use the example of insulin and glucagon in the control of blood glucose to explain the arrangement of paired hormone pathways. Use the figure provided.

Describe diabetes mellitus.

Describe Type I and Type II diabetes mellitus.

The endocrine and nervous systems act together to regulate animal physiology. How does the hypothalamus and pituitary gland (anterior and posterior pituitary) function in this process? Pathway Example Name the two hormones that are released from the Stimulus Suckling posterior pituitary and their function. +

Use the figure provided to explain the concept of Sensory positive feedback. neuron

Hypothalamus/ posterior pituitary

Neurosecretory cell Posterior pituitary secretes oxytocin ( ) Blood

vessel Positive feedbackPositive

Target Smooth muscle in Name the hormones that are released from the anterior pituitary. cells breasts

Response Milk release

Describe the hormone cascade pathway using the figure provided. Pathway Example

Stimulus Cold

Sensory neuron – Hypothalamus secretes thyrotropin-releasing hormone (TRH ) Neurosecretory cell

Blood vessel

– Anterior pituitary secretes thyroid-stimulating hormone (TSH or thyrotropin )

Negativefeedback Thyroid gland secretes thyroid hormone

(T3 and T4 )

Target Body tissues cells

Increased cellular Response metabolism

Differentiate between tropic and nontropic hormones.

Name the four strictly tropic hormones and their functions.

Name the two strictly nontropic hormones and their functions.

Describe growth hormone (GH) and its functions.

Define giantism and pituitary dwarfism. Using the figure provided describe the function and pathway of thyroid hormone.

Define hyperthyroidism. Describe Grave’s disease

Using the figure provided, explain how parathyroid hormone and calcitonin control blood calcium.

Calcitonin Thyroid gland releases calcitonin. Reduces Stimulates Ca2+ uptake Ca2+ deposition in kidneys in bones

STIMULUS: Blood Ca2+ Rising blood level declines Ca2+ level to set point

Homoeostasis: Blood Ca2+ level (about 10 mg/100 mL) Blood Ca2+ STIMULUS: level rises Falling blood to set point Ca2+ level Stimulates Parathyroid Ca2+ release gland from bones

PTH

Increases Ca2+ uptake 2+ in intestines Active Stimulates Ca vitamin D uptake in kidneys