Biology - Ch 6 - Endocrinology

Front 1

What does the endocrine system do?

Back 1

Acts as a means of internal communication, coordinating the activities of the organ systems.

Front 2

What do endocrine glands produce?

Back 2

Synthesis and secrete chemical substance called hormones directly into the circulatory system.

Front 3

How are endocrine glands different than exocrine glands?

Back 3

Endocrine goes directly into the blood stream.

Exocrine is released via ducts.

Front 4

Name the glands that synthesize and/or secrete hormones:

Back 4

pituitary
hypothalamus
thyroid
parathyroids
adrenals
pancreas
testes
ovaries
pineal
kidneys
gastrointestinal glands
heart
thymus

Front 5

What determines the specificity of a hormone?

Back 5

Specificity is determined by the presence of specific receptors on or in the target cells.

Front 6

Where are the adrenal glands located and what are their names?

Back 6

The adrenal glands are located on top of the kidneys.

Two Parts:
Adrenal Cortex
Adrenal Medulla

Front 7

What does the adrenal cortex do?

Back 7

In response to stress, ACTH (produced by anterior pituitary) stimulates the adrenal cortex to synthesize and secrete corticosteroids.

Front 8

What are the different types of corticosteriods that are produced by the adrenal cortex?

Back 8

Glucocorticoids
Mineralocorticoids
Cortical sex hormones

Front 9

What are glucocorticoids?

Back 9

Cortisol or Cortisone

Involved in glucose regulation and protein metabolism.

Glucocorticoids raise blood sugar levels by promoting protein breakdown and gluconeogenesis and decreasing protein synthesis.

Raise plasma glucose levels.

Antagonistic to effects of insulin.

Front 10

What are mineralocorticoids?

Back 10

Aldosterone

Regulate plasma levels of sodium and potassium, as a result, total extracellular water volume.

Causes active reabsorption of sodium and passive reabsorption of water in the nephron.

Results in increase in both blood volume and blood pressure.

Front 11

What are cortical sex hormones?

Back 11

Adrenal cortex secretes small quantities of androgens (male sex hormones)

Effects are limited in males due to a bulk of androgens produced in testes.

Woman may have excess facial hair however.

Front 12

What does the Adrenal Medulla do?

Back 12

Produces epinephrine (adrenaline) and norepinephrine (noradrenaline), both belonging to a class of amino acid-derived compounds called catecholamines.

Front 13

What does epinephrine and norepinephrine do?

Back 13

Epinephrine increases the conversion of glycogen to glucose in liver and muscle tissue, causing a rise in blood glucose levels and increase in basal metabolic rate.

Both epinephrine and norepinephrine increase rate and strength of heart beat, and dilate and constrict the blood vessels to increase blood flow to brain, heart, and skeletal muscles while decreasing flow to viscerals.

"fight or flight" response

Both hormones are also neurotransmitters.

Front 14

How are the adrenal hormones controlled?

Back 14

Release of adrenal cortical hormones is under the control of adrenocorticotrophic hormone (ACTH), hormone secreted by anterior pituitary gland.

ACTH stimulates production of glucocorticocoids and sex steroids; aldosterone production is controlled by a different mechanism.

Front 15

Where is the pituitary gland located and what does it look like?

Back 15

Small, tri-lobed gland lying at the base of the brain.

Two main lobes, anterior and posterior are functionally distint. The third intermediate lobe in humans is rudimentary.

Front 16

What does the anterior pituitary gland synthesize?

Back 16

Direct Hormones - Stimulate target organs
Tropic Hormones - Stimulate the release of other endocrine gland hormones.

Front 17

What are the hormones produced by the anterior pituitary?

Back 17

F SH
L H
A CTH
T SH

P rolactin
i (gnore)
G H

Front 18

What are the Tropic hormones?

Back 18

Follicle-stimulating hormone (FSH)
Luteinizing Hormones (LH)
Adrenocorticotropic hormone (ACTH)
Thyroid-Stimulating hormone (TSH)

Front 19

What is Follicle-Stimulating Hormone?

Back 19

Follicle-stimulating hormone (FSH) - In females causes maturation of ovarian follicles which begin secreting estrogen. In males, stimulates maturation of the seminiferous tubules and sperm production.

Front 20

What are Lutenizing Hormones?

Back 20

Luteinizing Hormones (LH) - In females, stimulate ovulation and formation of the corpus luteum. In males, stimultes the interstitial cells of tests to synthesize testosterone.

Front 21

What is Adrenocorticotropic hormone (ACTH)?

Back 21

Adrenocorticotropic hormone (ACTH) - Stimulates the adrenal cortex to synthesize and secrete glococorticoids and is regulated by the releasing hormone corticotrophin releasing factor (CRF).

Front 22

What is Thyroid-Stimulating hormone (TSH)?

Back 22

Thyroid-Stimulating hormone (TSH) - Stimulates the thyroid gland to synthesize and release thyroid hormone including thyroxin.

Front 23

What does the posterior pituitary gland do?

Back 23

Does not synthesize hormones.

Stores and releases peptide hormones oxytocin and ADH, both produced by hypothalamus.

Hormone secretion is stimulated by action potential from hypothalamus.

Front 24

What does oxytocin do?

Back 24

During childbirth, increases strength and frequency of uterine contractions.

Oxytocin secretion is also induced by suckling and stimulates milk production in mammary glands.

Front 25

What does Antidiuretic Hormone (ADH, vasopressin) do?

Back 25

Increases permeability of nephron's collecting duct to water, thereby promoting water reabsorption and increasing blood volume.

Secreted when plasma osmolarity increases, as sensed by hypothalamus; or when blood volume decreases, as sensed by circulatory system.

Front 26

Where is the hypothalamus located and what does it do?

Back 26

Part of forebrain and located directly above the pituitary gland.

Receives neural transmissions from brain and rest of body that triggers specific response of secretory cells.

Hypothalamus regulates pituitary glands via negative feedback and through the actions of inhibiting and releasing hormones.

Front 27

How does the hypothalamus control the Anterior Pituitary?

Back 27

Control occurs via portal vein that connects the two parts, communication is very quick this way.

Front 28

How does the hypothalamus control the Posterior Pituitary?

Back 28

Neurosecretory cells in the hypothalamus synthesis oxytocin and ADH and transport to posterior pituitary for storage and secretion.

Front 29

Where is the thyroid located and what does it do?

Back 29

Bi-lobed structure located on the ventral surface of the trachea.

It produces Thyroid Hormones (Thyroxine and Triiodothyronine) and calcitonin.

Front 30

What do the thyroid hormones (Thyroxine and Triiodothyronine) do?

Back 30

Thyroxine and Triiodothyronine are derived from the iodination of the amino acid Tyrosine.

Thyroid hormones are necessary for growth and neurological development in children.

They increase the rate of metabolism throughout the body.

Front 31

What happens and is the result of hypothyroidism?

Back 31

Thyroid hormones are undersecreted or not secreted at all.

Symptoms - Slowed heart rate and respiratory rate, fatigue, cold intolerance, weight gain.

In infants (cretinism) characterized by mental retardation and short stature.

Front 32

What happens and is the result of hyperthyroidism?

Back 32

Thyroid is overstimulated

Symptoms: increased metabolic rate, feelings of excessive warmth, profuse sweating, palpitations, weight loss, protruding eyes.

Front 33

What does thyroid hormone calcitonin do?

Back 33

Calcitonin decreases Ca2+ concentration by inhibiting release of Ca2+ from the bone.

Regulated by plasma Ca2+ levels.

Antagonistic to parathyroid hormone.

Front 34

Where are the parathyroid glands located and what do they do?

Back 34

Four small pea-shaped structures located on posterior side of Thyroid gland.

Synthesize and secrete parathyroid hormone (PTH).

PTH raises Ca2+ concentration in blood by breaking down bone.

Bone contains phosphate and calcium and PTH releases both.

PTH compensates by having kidney excrete phosphate.

Front 35

Where is the Pancreas and what does it do?

Back 35

Pancreas lies mid body horizontal (shaped like seven).

Pancreas is exocrine (cells secrete digestive enzymes to small intestine via ducts) and endocrine (smaller glandular structures called islets of Langerhans that secrete glucagon and insulin).

Front 36

What does glucagon do?

Back 36

Stimulates:
protein and fat degradation,
conversion of glycogen to glucose,
gluconeogenesis.

All serve to increase blood glucose levels.

Front 37

What does insulin do?

Back 37

Stimulates:
Uptake of glucose by cells and muscles,
storage of glycogen in muscle and liver cells,
synthesis of fats from glucose,
uptake of amino acids.

Antagonist to glucagon and glucocorticoids.

Underproduction of insulin leads to diabetes mellitus, hyperglycemia

Front 38

Plasma Glucose in a Nutshell

Back 38

Insulin decreases plasma glucose.
Glucagon increases plasma glucose.

Also, growth hormone, glucocorticoids, epinephrine are also capable of increasing plasma glucose

Front 39

Ca2+ Levels in a Nutshell

Back 39

PTH increases Ca2+
CalciTONIN tones down Ca2+

Front 40

What do the kidneys do?

Back 40

When blood volume falls, the kidneys produce renin, renin converts plasma protein angiotensinogen to angiotensin I which is converted to angiotensin II, which stimulates adrenal cortex to secrete aldosterone, which helps to restore blood volume by increasing sodium reabsorption at the kidney, leading to an increase in water.

Blood volume falls => kidneys produce renin -> renin converts angiotensinogen to angiotensin I -> angiotensin I converted to angiotensin II -> angiotensin II stimulates adrenal cortex to release aldosterone => increased sodium resorption -> increased water volume

Front 41

What are the gastrointestinal hormones and what do they do?

Back 41

Food stimulates the stomach to release the hormone gastrin.

Gastrin - carried to gastric glands and stimultes the gland to secrete HCl in response to food in stomach.

Secretin - Released by small intestine once food enters from stomach. Basic solution to neutralize the chyme from stomach.

Cholecystokinin - Released from small intestine in response to the presence of fats and causes contraction of the gallbladder and release of bile in small intestine. Bile aids in digestion of fats.

Front 42

What does Bile do?

Back 42

Aids the small intestine in the digestion of fats.

Front 43

Where is the pineal gland located and what does it do?

Back 43

Pineal gland is a tiny structure at the base of the brain that secretes the hormone melatonin.

Front 44

What is the role of meletonin?

Back 44

Believed to have a role in circadian rythems

Melatonin secretion is regulated by light and dark cycles of the environment

Front 45

What two major groups are hormones classified in?

Back 45

Peptide Hormones
Steroid Hormones

Front 46

What two ways can hormones affect the activities of their target cells?

Back 46

Via extracellular receptors, or

Via intracellular receptors

Front 47

Peptide Hormones

Back 47

Range from simple short peptides to complex polypeptides

Their binding to specific receptors on the surface of their target cells triggers a series of enzymatic reactions within each cell

Often results in cascade effect

Front 48

Steroid Hormones

Back 48

Lipid derived molecules with a characteristic ring structure

Produced by testes, ovaries, placenta, adrenal cortex

Because they are lipid soluble, enter the cell and directly bind with specific receptor proteins in the cytoplasm.

Receptor hormone can then directly enter the nucleus to affect the transcription of specific DNA and protein synthesis

Front 49

What are plant hormones primarily involved in?

Back 49

Plant hormones are primarily involved in the regulation of growth

Produced by actively growing portions of the plant such as meristematic tissues in apical region of shoots and roots, or in young, growing leaves, and developing seeds.

Front 50

Auxins

Back 50

Important class of plant hormones associated with several types of growth patterns

auxins stimulate the production of new xylem cells

Types:
Phototropism
Geotropism
Inhibition of lateral buds

Front 51

What is phototropism?

Back 51

Auxins are responsible for the tendency of shoots of plants to bend towards light sources.

When light strikes the tip of a plant from one side, the auxin supply on that side is REDUCED.

Illuminated side growth is reduced and grows more slowly than shaded side, thus plant bends toward light.

Front 52

What is geotropism?

Back 52

Growth of portions of plants towards or away from gravity.

Negative Geotropism - Causes shoots to grow upwards.

A plant placed on its side:
Lower side has increased concentration of auxins compared to top side. Plant growth is greater on bottom and plant will grow upward.

Positive Geotropism - Causes roots to grow towards gravity. Effect is opposite of negative geotropism with greater auxin resulting in lesser growth.

Front 53

What are gibberellins?

Back 53

Stimulate rapid stem elongation, particularly in plants that normally do not grow tall (dwarf plants).

Inhibit formation of new roots and stimulate production of new phloem cells by cambium (whereas auxins stimulate the production of new xylem cells)

Terminate the dormancy of seeds and buds.

Induce some biennial plants to flower during their first year of growth.

Front 54

What are Kinins?

Back 54

Promote cell division

Important type of cytokinin

Ratio of kinetin to auxin is of particular importance in the determination of the timing of the differentiation of new cells.

Action of kinetin is enhanced when auxin is present.

Front 55

What does Ethylene do?

Back 55

Stimulates fruit ripening.

Also induces senescence, or aging.

Front 56

Plant Growth Inhibitors

Back 56

Block cell division

Important in maintaining dormancy in buds and seeds of plants during autumn and winter.

Some destroyed by cold so they begin growing in the first growth season.

Front 57

Anti-Auxins

Back 57

Help regulate the activity of Auxins.

Increase in one results in the increase of the other.