Biology 30 - Unit 1 Booklet 3: The Endocrine System (Questions)

What two systems interact to maintain homeostasis?

Nervous system and endocrine system

How do the nervous and endocrine systems differ in terms of structure?

The nervous system is composed of nerve cells and tissues, while the endocrine system is composed of glandular tissues

How do the nervous and endocrine systems differ in terms of mode of action?

The nervous system transmit signals through electrochemical impulses aided by neurotransmitters, while the endocrine system releases chemicals called hormones into the blood that are carried through the body

How do the nervous and endocrine systems differ in terms of duration of response?

The nervous system’s response time is faster because it is transmitted through a quick electrical impulse, while the endocrine system’s response time is slower due to hormones being carried by blood and thus being contolled by heart rate

How do the nervous and endocrine systems differ in terms of areas targeted?

The nervous system targets localized areas such as effectors, while the endocrine system targets generalized areas such as receptor sites

What is the goal of the endocrine system?

Achieve homeostasis

Explain how the endocrine system uses negative feedback.

The problem stimulus activates a neuron, relaying a signal to the CNS. The CNS relays this signal to the endocrine system, which secretes a hormone throughout the body in order to solve the problem

What type of processes in the body do hormones control?

Slow/continuous processes

Where are hormones created?

Endocrine/ductless glands

1

Pineal gland

2

Parathyroid

3

Hypothalamus

4

Pituitary gland

5

Thyroid

6

Thymus

7

Adrenal gland

8

Pancreas

9

Testes

10

Ovaries

2

Pituitary gland

4

Pineal gland

1

Hypothalamus

3

Optic chiasm

2

Pituitary gland

8

Pons

What is the role of the posterior pituitary?

Holds and secretes hormones directly produced by neurons in the hypothalamus into the blood to reach targets

What is the role of the anterior pituitary?

Produces hormones that are stimulated to be released and created by the hypothalamus and secretes them into the blood to reach targets

What is the relationship between the hypothalamus and the endocrine system?

The hypothalamus is the master control center of the endocrine system, as it commands the pituitary gland to secrete hormones that influence numerous body functions

What hormones are controlled by the hypothalamus/posterior pituitary?

Oxytocin, ADH

What hormones are controlled by the anterior pituitary?

hGH, TSH, ACTH, prolactin, FSH, LH

Describe the negative feedback of high blood sugar.

When blood sugar is high, the beta islet cells of the pancreas stimulate the release of insulin, causing the body cells to increase permeability to glucose and the liver to store excess glucose as glycogen. As a result, blood sugar lowers and homeostasis is reached. The release of insulin shuts off the islets, turning them off to prevent excess insulin release.

Describe the negative feedback of low blood sugar.

When blood sugar is low, the alpha islet cells of the pancreas stimulate the release of glucagon, causing the liver to release glucose from glycogen stores. As a result, blood sugar is raised and homeostasis is reached. The release of glucagon shuts off the islets, turning them off to prevent excess glucagon release.

What is a telltale sign of diabetes mellitus that is also used as a diagnostic tool?

Glucose in the urine due to the kidneys being unable to reabsorb all the excess blood glucose that is filtered through them

Where are the adrenal glands located?

Above the kidneys

1

Adrenal cortex

2

Adrenal medulla

What does the adrenal cortex control?

Long term stress (release and creation of cortisol) and production of other hormones including testosterone, estrogen, and aldosterone

What does the adrenal medulla control?

Short term stress (release and creation of epinepherine)

What controls the adrenal cortex?

ACTH from anterior pituitary

Describe the negative feedback of the long-term stress response.

When faced with long-term stress, the anterior pituitary stimulates the release of ACTH to the adrenal cortex, which then stimulates the release of cortisol to the body. This causes fats and proteins (muscle mass, immune system, etc.) to release glucose from long-term energy storage. The release of cortisol shuts off the anterior pituitary, preventing excess cortisol release

What are the adrenal cortex and adrenal medulla controlled by, respectively? Why is this significant?

The adrenal cortex is controlled by the endocrine system (anterior pituitary), while the adrenal medulla is controlled by the nervous system. This is significant because the response times of the two systems differ, thus making it more convenient for the medulla’s role of handling short-term stress to be controlled by the fast response of the nervous system and the cortex’s role of handling long-term stress to be controlled by the long-lasting response of the endocrine system

Describe the negative feedback of metabolism.

When the body is not metabolizing nutrients efficiently, the hypothalamus stimulates the release of TSH from the anterior pituitary to the thyroid, which then stimulates the release of thyroxine to the body. This causes the body cells to increase metabolism. As a result, homeostasis is reached. The release of thyroxine, in the presence of iodine, shuts off the anterior pituitary and hypothalamus, turning them off to prevent excess thyroxine release

What is the role of iodine in metabolism?

Is an important component to building thyroxine and ensures that the negative feedback system for thyroxine works

How does hGH stimulate body growth?

Stimulates elongation of skeleton, causes cells of soft tissues and bones to increase in number of cells, and breaks down fats to increase fatty acid levels

Describe the negative feedback of high calcium in the body.

When the body has too much calcium, the thyroid stimulates the release of calcitonin, causing the bone to store calcium and the kidneys and intestines to lose it. As a result, calcium is lowered and homeostasis is reached. The release of calcitonin shuts off the thyroid, turning it off to prevent excess calcitonin release

Describe the negative feedback of low calcium.

When the body does not have enough calcium, the parathyroids stimulate the release of PTH, causing the bone to lose calcium and the kidneys and intestines to store it. As a result, calcium is raised and homeostasis is reached. The release of PTH shuts off the parathyroids, turning them off to prevent excess PTH release

Describe the negative feedback of thirst regulation.

When the body needs water, osmoreceptors in the hypothalamus shrink, causing the CNS to stimulate the sensation of thirst. The hypothalamus/pituitary complex create and release ADH to the kidney, causing the distal tube and collecting duct to become permeable to water and reabsorb water in the body. As a result, the body is rehydrated and homeostasis is reached. The release of ADH and reabsorption of water causes the osmoreceptors in the hypothalamus to swell, stopping the release of ADH

Where does aldosterone act on?

Acts on distal tubule and collecting duct

What does aldosterone do?

Increases sodium reabsorption, which inreases blood volume and blood pressure. Stimulated by low blood pressure