Hormones And The Endocrine System

Front 1

Releasing hormone

Back 1

Secreted from the hypothalamus, stimulates the release of hormones from the anterior pituitary. Ex. Thyrotropin releasing hormone

Front 2

Inhibiting hormone

Back 2

Secreted from the hypothalamus, inhibits the release of hormones from the anterior pituitary

Front 3

Tropic hormone

Back 3

Regulates the function of endocrine cells or glands. Three important types: Thyroid-stimulating, follicle-stimulating, luteinizing.

Front 4

What are hormones?

Back 4

Endocrine signals are secreted into extracellular fluids and travel via the bloodstream to communicate regulatory messages within the body.

Front 5

What are two specific differences between the endocrine and nervous systems?

Back 5

Endocrine: Secretes hormones that react with specific receptors to coordinate slower, longer-lasting responses.
Nervous: Convey high-speed electrical signals along specific pathways for fast-acting responses.

Front 6

What are the five different types of secreted signaling molecules?

Back 6

Hormones: Endocrine signals secreted to convey messages within the body via the bloodstream
Local regulators: Chemical signals that travel over short distances by diffusion to reach their target cells
Neurotransmitters: Diffuse a short distance to bind receptors on target cells
Neurohormones: Originate from neurosecretory cells in the brain that secrete molecules that diffuse into the bloodstream
Pheromones: Chemical signals that are released into the external environment with the purpose of communicating with other members of the same species

Front 7

What is the difference between an endocrine gland and an exocrine gland?

Back 7

Endocrine gland: Ductless, secrete hormones directly into the surrounding fluid
Exocrine gland: Have ducts, secrete substances onto body surfaces or into body cavities (tear ducts, salivary glands)

Front 8

What is a local regulator?

Back 8

Chemical signals that travel over short distances by diffusion to reach their target cells. Function in blood pressure regulation, nervous system function, and reproduction.

Front 9

What are the two different classes of local regulators and how do they differ?

Back 9

Paracrine signaling: Secreted molecules act on cells near the secreting cells
Autocrine signaling: Secreted molecules act on the secreting cell itself

Front 10

What is the difference between a neurotransmitter and a neurohormone? Give an example.

Back 10

Neurotransmitter: Diffuse a short distance to bind receptors on target cells
Neurohormone: Originate from neurosecretory cells in the brain that secrete molecules that diffuse into the bloodstream
Ex. ADH (vasopressin) secreted by brain and travels through bloodstream to kidneys

Front 11

What are pheromones? How might they be used?

Back 11

Pheromones: Chemical signals released into the external environment, used for communication with other members of the same species. This includes marking trails leading to food sources, warning of predators, and attracting potential mates

Front 12

What are the three major classes of molecules that function as hormones? Which are water-soluble and which are lipid-soluble?

Back 12

Polypeptides: Proteins and peptides, water soluble
Amines: Derived from amino acids, water soluble
Steroid hormones: Lipid soluble

Water soluble: Secreted by exocytosis, travel freely in bloodstream, and bind to cell-surface receptors
Lipid soluble: Diffuse across cell membranes, travel in bloodstream bound to transport proteins, and diffuse through the membrane of target cells

Front 13

What is the correlation between the solubility of a hormone and the location of its receptors?

Back 13

A water soluble hormone binds to a receptor protein on the surface of a target cell. A lipid soluble protein binds to a receptor protein either in the cytoplasm or in the nucleus.

Front 14

In addition to receptor location, water-soluble and lipid-soluble hormones also exhibit additional differences in their response pathways. What are these differences?

Back 14

Water soluble: Binding triggers events at the plasma membrane that result in a cellular response, or alter transcription of specific genes (gene regulation) which then affects the cytoplasmic response.
Lipid soluble: The activation of a receptor directly triggers the cell’s response, which is often a change in gene expression.

Front 15

What is a signal transduction pathway?

Back 15

Signal transduction pathway: A series of steps by which a signal on a cell’s surface is converted in to a specific cellular response

Front 16

Signaling by a hormone involves three key events. What are they?

Back 16

1.Reception: Message received, binds to receptor
2.Signal Transduction: Transfer of signal into cell itself
3.Response: Response by effector

Front 17

What is a G protein coupled receptor? Provide an example of a hormone that utilizes a G protein coupled receptor in its signal transduction pathway.

Back 17

G protein coupled receptor:
A receptor that activates a G protein when a signalling molecule attaches to the receptor. The G protein activates an enzyme, causing a cellular response. The hormone epinephrine, secreted by the adrenal glands, binds to these cells to eventually activate protein kinase A, which leads to the inhibition of glycogen synthesis and the promotion of glycogen breakdown. This allows the liver to release glucose into the bloodstream.

Front 18

If someone said to you that a particular hormone utilizes a G protein coupled receptor in its transduction pathway, would they be talking about a water- or lipid-soluble hormone?

Back 18

Water-soluble

Front 19

Where is the receptor for a lipid-soluble hormone located? (hint: It can be found in either of two locations)

Back 19

Cytoplasm or nucleus.

Front 20

What is the typical cellular response initiated by a lipid-soluble hormone?

Back 20

A change in gene expression.

Front 21

What is a transport protein and why do lipid-soluble proteins require them? (hint: see slide 17)

Back 21

Transport proteins aid in the transfer of solutes across membranes. They are necessary for lipid-soluble proteins to travel through the bloodstream .

Front 22

Why can the same hormone have different effects on different body tissues?

Back 22

The target cells may have different receptors for the hormone, or there may be different signal transduction pathways and/or effector proteins.

Front 23

In the “Fight or Flight Response” the release of epinephrine from the adrenal medulla causes skeletal muscle blood vessels to dilate while simultaneously constricting blood vessels of the intestine. Explain how this is possible.

Back 23

The skeletal muscle blood vessels and blood vessels of the intestine have different receptors for epinephrine, and therefore different responses. Epinephrine triggers kinase A, which inactivates a muscle specific enzyme responsible for the contraction of smooth muscle. The smooth muscle relaxes, allowing the skeletal muscle blood vessels to receive more blood. Epinephrine triggers a distinct signaling pathway involving a different G protein and different enzymes in the intestinal blood vessels, causing the smooth muscles to contract and restricting blood flow to the intestine.

Front 24

List the three types of local regulators discussed in class and explain their function.

Back 24

Cytokines and growth factors: Immune responses, stimulate cell proliferation and differentiation
Nitric Oxide (NO): Improves blood flow, produces erections (Viagra interferes with breakdown of NO)
Prostaglandins: Promote fever and inflammation, intensify sensation of pain, induce labor, stimulate smooth muscles of uterine wall to help sperm reach an egg, regulation of aggregation of platelets (Aspirin & ibuprofen- Inhibit prostaglandins, however ibuprofen is selective, aspirin is not)

Front 25

Hormonal pathways generally operate on the principle of ??????????????????, in which the response to the stimulus leads to a reduction in the stimulus.

Back 25

negative feedback

Front 26

Some homeostatic control systems rely on sets of simple hormone pathways with coordinated activities. One common arrangement is a pair of pathways each counter-balancing the other. Give an example. What is the advantage of this arrangement?

Back 26

The hormones insulin and glucagon are arranged to keep blood glucose balanced. Insulin lowers blood glucose levels when the levels are above the set point, and glucagon increases blood glucose levels when the levels are below the set point. This arrangement is an example of negative feedback and maintains homeostasis in the body.

Front 27

Explain the action of insulin and glucagon on blood glucose levels.

Back 27

Insulin: Reduces blood glucose levels by promoting the cellular uptake of glucose, slowing glycogen breakdown in the liver, and promoting fat storage.
Glucagon: Increases blood glucose levels by stimulating the conversion of glycogen to glucose in the liver and stimulating the conversion of glycerol and amino acids to glucose.

Front 28

In response to low blood glucose levels, which hormone (glucose or glucagon) would be released?

Back 28

The hormone glucagon would be produced because it stimulates the production of glucose. Glucose is not a hormone.

Front 29

What is diabetes mellitus? How is it caused? What hormone is lacking?

Back 29

Diabetes mellitus: An endocrine disorder caused by a deficiency of insulin or a decreased response to insulin.

Front 30

How does type I diabetes differ from type II?

Back 30

Type I diabetes (Insulin-dependent): Autoimmune disorder where the immune system destroys pancreatic beta cells, hereditary and environmental influences
Type II diabetes (Non-insulin-dependent): Insulin deficiency or reduced response of target cells due to change in insulin receptors, environmental influences

Front 31

In the caterpillar, molting and metamorphosis are under the control of the same hormone. What is the hormone? How are these separate developmental pathways controlled by the same hormone?

Back 31

Ecdysone: Released from the prothoracic glands, promotes molting in the presence of juvenile hormone and promotes development of the pupal form within which metamorphosis occurs in the absence of the juvenile hormone

Front 32

What is the part of the vertebrate brain that receives information from the nervous system and initiates responses through the endocrine system?

Back 32

Hypothalamus

Front 33

How do the anterior and posterior pituitary differ with respect to the production and release of hormones?

Back 33

Posterior pituitary: Stores and secretes hormones that are made in the hypothalamus
Anterior pituitary: Makes and releases hormones under regulation of the hypothalamus

Front 34

Which hormones are produced by the posterior pituitary? On which tissues do they act?

Back 34

Oxytocin and antidiuretic hormone (ADH) act directly on nonendocrine tissues

Front 35

What does oxytocin do?

Back 35

Induces uterine contractions and the release of milk

Front 36

What type of feedback system is involved in milk release by oxytocin?

Back 36

Positive feedback. Suckling sends a message to the hypothalamus via the nervous system to release oxytocin, which further stimulates the milk glands.

Front 37

What hormones are produced by the anterior pituitary? On which tissues do they act?

Back 37

Follice Stimulating Hormones (FSH) and Luteinizing Hormones (LH), Thyroid Hormone (TH), Adrenocorticotropic Hormones (ACTH), Prolactin, Melanocyte Stimulating Hormone (MSH), and Growth Hormone (GH). The tropic hormones (FSH, LH, TSH, ACTH, and TH) act on endocrine cells of glands. Nontropic hormones (PRL and MSH) act on nonendocrine tissues.GH does both.

Front 38

Diagram the hormone cascade pathway for the release of thyroid hormone. What type of feedback system is employed here? Which hormones are inhibited by rising thyroid hormone levels in the blood?

Back 38

Negative feedback. Inhibits the release of Thyroid Stimulating Hormone (TSH) and Thyrotropin Releasing Hormone (TRH).

1. Stimulus response- Hypothalamus secretes thyrotropin-releasing hormone (TRH)
2. Pituitary response- Anterior pituitary secretes thyroid-stimulating hormone (TSH) to an endocrine gland
3. Endocrine gland response- Endocrine gland (thyroid) secretes thyroid hormone (TH)
4. Thyroid Hormone response- Exerts negative feedback on hypothalamus and anterior pituitary (inhibits TSH and TRH), preventing overreaction to stimulus