Hormonal Regulation of Homeostasis

Question 1

Why do nervous system responses tend to be more rapid than endocrine system responses?

Answer 1

NS messages tend to be transmitted rapidly to precise locations in the body, such as the reflex arc that causes you to withdraw your hand from a hot stove.

In addition to cellular communications through neurone, the body secretes chemical messengers from glands.

Question 2

Define the term hormone using a specific example.

Answer 2

Hormones - endocrine glands secrete chemical messengers.

For example: Pancreas - secrete the hormone insulin.

Question 3

Provide four reason why the distinction between the nervous and endocrine systems is sometimes blurred.

Answer 3

1. Some Nervous system tissues secrete hormones, such as cells in the hypothalamus, pituitary gland. and adrenal glands.
2. Several chemicals functions as both transmitters and hormones, depending on their location in the body. For Example - Epinephrine, which acts as neurotransmitter between certain neurone in NS
3. The endocrine and NS both include responses that are regulated by negative feedback loops.
4. The regulation of several physiological processes involves both the nervous and endocrine systems acting in conjunction

Question 4

How did Adolph Berthold’s experiment with roosters demonstrate the function of an endocrine gland?

Answer 4

Berthold took six young male chickens, and castrated four of them. The other two were left to develop normally and used comparatively as control samples. Two of the castrated chickens were left to become chicken eunuchs. But what Berthold did with the other two castrated chickens is what really changed endocrinology. He transplanted the testes back into these two chickens at a distant site from where they were originally. The two castrated chickens never matured into roosters with adult combs or feathers. But the chickens who received transplanted testes did mature into normal adult roosters. This experiment revealed that hormones that could access the blood stream from any site would function correctly in the body and that hormones did, in fact, travel freely in the circulation.

Question 5

What are some of the challenges for researchers studying the endocrine system?

Answer 5

• They removed functions from the test animals and observing the effects.
• The techniques did not always provides best results because different hormones often work together.
• Another fact, the gland or hormone can compensate for one that is mission.
• Aldo some glands produce more than one hormone

For Example: Parathyroid gland are embedded in the thyroid tissue. Both tissue produce different hormones, however, which have different effects on the body.

Question 6

Briefly describe two technologies used to study hormones and endocrine glands

Answer 6

• Nuclear Scanning devices PET
• High-powered microscopes

-Scientist to visualize glands, hormones, and target fell membranes in detail

Question 7

What are the two major groups of hormones? How do they interact with their target cells?

Answer 7

• Lipids - Steroid hormone; testosterone, estrogen, and cortisol
• Amino Acids/Water-Soluble - Epinephrine, Human Growth Hormones, Thyroxine, Insulin
• Each target cell contains receptors proteins.
• Circulating hormones bind to their specific receptor proteins, much like a key fits into a lock.

Question 8

How do a hormones stimulate a response in a target cells?

Answer 8

Hormones cause cellular changes by binding to receptors on target cells. The number of receptors on a target cell can increase or decrease in response to hormone activity. Hormones can affect cells directly through intracellular hormone receptors or indirectly through plasma membrane hormone receptors.

Question 9

Identify which glands secrete the following hormones:

• Thyroxine
• Human Growth Hormone
• Cortisol
• Insulin
• Glucagon

Answer 9

Question 10

Describe how the secretion of ADH is regulated by negative feedback.

Answer 10

• When the blood plasma becomes too concentrated, receptors in the hypothalamus detect this and send a neural signal to the posterior pituitary gland to release ADH.
• The waster is reabsorbed, the body excretes less ( but more concentrated) urine, and blood pressure increases.
• The hypothalamus detects this and send a signal to the posterior pituitary to stop secreting ADH.

Question 11

What is a tropic hormone?

Answer 11

Tropic Hormones -Many of hormones released from the anterior pituitary and the hypothalamus

• Their target are other endocrine glands
• Tropic Hormones stimulate endocrine glands to release other hormones

Question 12

How is the secretion of tropic hormones from the pituitary gland regulated?

Answer 12

• The Hypothalamus secretes a releasing hormones into the anterior pituitary; this causes the anterior pituitary to release a tropic hormones into the bloodstream.
• The tropic hormones then stimulates the target gland to release third hormones into the blood.
• This hormones travels to another target tissue and produces an effect.
• This system is also which the third hormones prevents further release of the first two hormones in the pathway

Question 13

Compare the anterior and posterior pituitary

Answer 13

Anterior Pituitary - a true hormones- synthesizing gland.

A blood vessels called a portal system carries releasing hormones from the hypothalamus to the anterior pituitary, and these hormones either stimulate or inhibits the release of hormones from this gland

Produce and release Six Major Hormones:

• Human growth hormones (hGH)
• Prolactin (PRL)
• Thyroid- Stimulating Hormones (TSH)
• Adrenocorticotropic Hormones (ACTH)
• Follicle-Stimulating Hormones (FSH)
• Leutinizing Hormones (LH)

Posterior Pituitary - considered part of the NS

Does. not produce any hormones; instead, it stores and releases the hormones, ADH, and oxytocin, which are produced in the hypothalamus and transferred to the posterior pituitary by neuronal axons.

Question 14

List three effects of hGH on the body.

Answer 14

1. Protein synthesis
2. Cell division of cartilage, bone, and muscle growth of cartilage, bone, and muscle
3. Metabolic breakdown and release of fats stored in adipose (fat) tissue

Question 15

Explain how the thyroid gland is like a metabolic thermostat.

Answer 15

Thyroid gland secrete immature thyroid hormones into the chambers between the cells.

Thyroxine, one of the hormones will become functional and be released into the bloodstream.

Question 16

Explain the role of thyroxine.

Answer 16

Thyroxine is the main hormone secreted into the bloodstream by the thyroid gland. It plays vital roles in digestion, heart and muscle function, brain development and maintenance of bones.

Question 17

Why does hypothyroidism cause a goitre to develop?

Answer 17

The damaged and inflamed tissues of the thyroid don’t produce enough hormones (hypothyroidism). When the pituitary gland detects the decline and prompts the thyroid to create more hormones, the thyroid can become enlarged.

Question 18

Describe what is meant by the fight-or-flight response.

Answer 18

short-term stress response = fight-or-flight

These hormones regulate a short-term stress response that is commonly referred to as the fight-or-flight response.

Question 19

How is the hypothalamus involved in the release of epinephrine and norepinephrine in the stress response?

Answer 19

The hypothalamus, a key player in the endocrine system, it activates the sympathetic nervous system. This, in turn, signals the adrenal glands to secrete epinephrine and norepinephrine into the bloodstream.

The release of epinephrine and norepinephrine is rapid because it is under NS control. Although the hormonal effects are similar to those of the sympathetic NS, their influence on the body lasts about 10x longer.

Question 20

Compare and contrast the major physiological changes that occur in the short-term and long-term stress response.

Answer 20

Question 21

How does cortisol make more glucose available to cells?

Answer 21

Cortisol - most abundant glucocorticoid and is a steroid hormones synthesized from cholesterol

• The brain detects danger, it directs the hypothalamus to secrete a releasing hormones. The releasing hormone stimulates the anterior pituitary to secrete adrenocorticotropic hormone (ACTH).
• ACTH targets the adrenal cortex, which causes he release of the stress hormones cortisol. Cortisol works often in conjunction with epinephrine, but is longer lasting. The main function of cortisol in the body is to raise the blood glucose levels.
• Cortisol does this by promoting the breakdown of muscle proteins into amino acids.
• The amino acids are taken out of the blood by the liver, where they are used to make glucose, which is then released back into the blood.
• Cortisol also prompts the breakdown of fat cells, which releases glucose.

Question 22

How does cortisol affect the immune system?

Answer 22

Cortisol is ordinarily anti-inflammatory and contains the immune response, but chronic elevations can lead to the immune system becoming “resistant,” an accumulation of stress hormones, and increased production of inflammatory cytokines that further compromise the immune response

Question 23

Describe how aldosterone increases blood pressure

Answer 23

Aldosterone causes an increase in salt and water reabsorption into the bloodstream from the kidney thereby increasing the blood volume, restoring salt levels and blood pressure.

Question 24

Describe how Addison’s disease affects the body.

Answer 24

Affected individuals may have a poor appetite and unintentional weight loss and may develop progressive fatigue and muscle weakness. Muscle pain (myalgia), muscle spasms and joint pain may also occur. Dehydration can also affect individuals with Addison’s disease.

Question 25

Identify two cell types of the islets of Langerhans and explain their functions.

Answer 25

Beta Cells - pancreas secretes insulin, which decreases the level of blood glucose.

Alpha Cells - Glucagon secreted and increases the level of blood glucose.

Question 26

Describe the roles of insulin and glucagon in maintaining homeostasis.

Answer 26

Insuline

1. Insulin circulates throughout the body and acts on specific receptors to make the target cells more permeable to glucose
2. It especially affects muscle cells, which use large amounts of glucose in cellular respiration, and liver cells, where glucose is converted into glycogen for temporary storage.
3. Other cells of the body also take in and use glucose for energy. As the glucose levels in the blood return to the homeostasis, insulin secretion slows.

Glucagon

1. Glucagon stimulates the liver to convert glycogen back into glucose, which is released into the blood.
2. Other hormones, such as hHG, cortisol, and epinephrine, also contribute to increasing the level of blood glucose.

Question 27

What are the symptoms of diabetes mellitus?

Answer 27

• Increased thirst.
• Frequent urination.
• Extreme hunger.
• Unexplained weight loss.
• Presence of ketones in the urine (ketones are a byproduct of the breakdown of muscle and fat that happens when there’s not enough available insulin)
• Fatigue.
• Irritability.
• Blurred vision.

Question 28

What is hyperglycaemia?

Answer 28

Hyperglycemia is the technical term for high blood glucose (blood sugar). High blood glucose happens when the body has too little insulin or when the body can’t use insulin properly.

Question 29

What are the effects of untreated diabetes mellitus on the body?

Answer 29

If left untreated, it can cause

• atherosclerosis (narrowing of blood vessels)
• heart disease,
• stroke,
• eye and kidney diseases.

Question 30

What interferes with the secretion of insulin in type 1 diabetes?

Answer 30

• The immune system produces antibodies that attack and destroy the beta cells of the pancreas
• The beta cells degenerate and are unable to produce insulin
• The condition is usually diagnosed in childhood, and people with it must have daily insulin injections in order to live.

Question 31

What risk factors are associated with developing type 2 diabetes?

Answer 31

• Weight. The more fatty tissue you have, the more resistant your cells become to insulin.
  Inactivity. …
• Family history. …
• Race or ethnicity. …
• Age. …
• Gestational diabetes. …
• Polycystic ovary syndrome. …
• High blood pressure.

Question 32

What was Banting and Best’s contribution to the treatment of diabetes?

Answer 32

Young surgeon named Frederick Banting and his assistant Charles Best figured out how to remove insulin from a dog’s pancreas and then isolate insulin from the islets.

Question 33

How can people with diabetes monitor their blood glucose levels?

Answer 33

• A blood glucose monitors
• An app that track blood glucose level.