Chapter 5: The Endocrine System

Question 1

The endocrine system consists of organs, known as ___________, that secrete hormones.

Answer 1

Glands

Question 2

____________ are signalling molecules that are secreted directly into the bloodstream to distant target tissues.

Answer 2

Hormones

Question 3

______________ are made up of amino acids, ranging in size from quite small (such as anti-diuretic hormone, ADH) to relatively large (such as insulin).

Answer 3

Peptide hormones

Question 4

Peptide hormones are released by ____________ after being packaged into vesicles in the Golgi apparatus

Answer 4

exocytosis

Question 5

Because peptide hormones are charged and cannot pass through the plasma membrane, they must bind to an extracellular receptor. The peptide hormone is considered the _______ messenger; it binds to the receptor and triggers the transmission of a second signal, known as the ________ messenger.

Answer 5

First messenger, second messenger

Question 6

The connection between the hormone at the surface and the effect brought about by second messengers within the cell is known as a _____________

Answer 6

Signalling cascade

Question 7

In the activation of G protein-coupled receptor system, the binding of a peptide hormone triggers the receptor to either activate or inhibit an enzyme called _____________, raising or lowering the levels of cAMP accordingly.

Answer 7

Adenylate cyclase

Question 8

cAMP can bind to intracellular targets, such as ____________, which phosphorylates transcription factors like cAMP response element-binding protein (CREB) to exert the hormone’s ultimate effect.

Answer 8

Protein kinase A

Question 9

Peptide hormones are _________-soluble, as they can travel freely in the bloodstream and usually do not require carriers.

Answer 9

Water-soluble

Question 10

____________ hormones are derived from cholesterol and are produced primarily by the gonads and adrenal cortex.

Answer 10

Steroid hormones

Question 11

One common form of conformational changes of steroid hormone-receptor complexes upon binding is ___________, or pairing of two receptor-hormone complexes.

Answer 11

Dimerization

Question 12

Steroid hormones are _________-soluble, so they must be carried by proteins in the bloodstream to travel around the body.

Answer 12

Lipid-soluble

Question 13

_____________ hormones are derived from one or two amino acids, usually with a few additional modifications.

Answer 13

Amino acid-derivative hormones

Question 14

The ____________ (epinephrine and norepinephrine) bind to the G protein-coupled receptors, while thyroid hormones bind intracellularly.

Answer 14

Catecholamines

Question 15

_____________ are secreted and act directly on a target tissue. For example, insulin released by the pancreas causes increased uptake of glucose by muscles.

Answer 15

Direct hormones

Question 16

_______________ require an intermediary to act. For example, gonadotropin-releasing hormone (GnRH) and luteinizing hormone (LH) do not cause direct changes in the physiology of muscle, bone, and hair follicles; they stimulate the production of another hormone by another endocrine gland that acts on these target tissues.

Answer 16

Tropic hormones

Question 17

By regulating the pituitary gland through tropic hormones, the ____________ is capable of having organism-wide effects.

Answer 17

Hypothalamus

Question 18

The release of hormones by the hypothalamus is regulated by _____________. ____________ occurs when a hormone (a product) later in the pathway inhibits hormone (or enzymes) earlier in the pathway.

Answer 18

Negative feedback

Question 19

The hypothalamus secretes compounds into the ____________, which is a blood vessel system that directly connects the hypothalamus with the anterior pituitary.

Answer 19

Hypophyseal portal system

Question 20

___________ is a alternative term for the pituitary.

Answer 20

Hypophysis

Question 21

Hypothalamus: Gonadotropin-releasing hormone (GnRH) -> Anterior pituitary: ____________ and ____________

Answer 21

Follicle-stimulating hormone (FSH) and luteinizing hormone (LH)

Question 22

Hypothalamus: Growth hormone-releasing hormone (GHRH) -> Anterior pituitary: ___________

Answer 22

Growth hormone (GH)

Question 23

Hypothalamus: Thyroid-releasing hormone (TRH) -> Anterior pituitary: ______________

Answer 23

Thyroid-stimulating hormone (TSH)

Question 24

Hypothalamus: Corticotropin-releasing factor (CRF) -> Anterior pituitary: ___________

Answer 24

Adrenocorticotropic hormone (ACTH)

Question 25

As long as the hypothalamus releases ____________, which is actually dopamine, no prolactin will be released.

Answer 25

Prolactin-inhibiting factor (PIF)

Question 26

The release of corticotropin-releasing factor (CRF) from the hypothalamus will stimulate the anterior pituitary to secrete adrenocorticotropic hormone (ACTH). ACTH will then cause the adrenal cortex to increase the level of ___________ being secreted into the blood.

Answer 26

Cortisol

Question 27

Three-organ systems, such as the hypothalamic-pituitary-adrenal (HPA) _______, are commonly referred to as _______.

Answer 27

Axis, axes

Question 28

__________ stimulates uterine contractions during labor, as well as milk letdown during lactation. It is released from the posterior pituitary.

Answer 28

Oxytocin

Question 29

___________ (also called vasopressin) increases reabsorption of water in the collecting ducts of the kidneys. It is secreted (in posterior pituitary) in response to increased plasma osmolarity, or increased concentration of solutes within the blood.

Answer 29

Antidiuretic hormone (ADH)

Question 30

The ____________ synthesizes and secretes 7 different products. Four of these are tropic hormones, while the other three are direct hormones.

Answer 30

Anterior pituitary

Question 31

Products of the anterior pituitary: FLAT PEG

Answer 31

- Follicle-stimulating hormone (FSH) - Luteinizing hormone (LH) - Adrenocorticotropic hormone (ACTH) - Thyroid-stimulating hormone (TSH) - Prolactin - Endorphins - Growth hormone (GH)

Question 32

____________ is more important in females than I males; it stimulates milk production in the mammary glands.

Answer 32

Prolactin

Question 33

When estrogen, progesterone, and __________ levels drop, that the block on milk production is removed and lactation usually begins.

Answer 33

Dopamine

Question 34

___________, a direct hormone that decrease the perception of pain.

Answer 34

Endorphins

Question 35

___________ promotes the growth of bone and muscle. It prevents glucose uptake in tissues that are not growing and stimulates the breakdown of fatty acids.

Answer 35

Growth hormone (GH)

Question 36

Bone growth originates in special regions of the bone known as ______________, which seal shut during puberty.

Answer 36

Epiphyseal plates

Question 37

An excess of growth hormone (GH) released in childhood (before epiphyseal plates closure) can cause ___________

Answer 37

Gigantism

Question 38

A deficit of growth hormone (GH) in childhood (before epiphyseal plates closure) results in __________

Answer 38

Dwarfism

Question 39

In adults, __________ is a medical condition that growth hormones has an effect on smaller bones (usually in hands, feet, and head).

Answer 39

Acromegaly

Question 40

_____________ is secreted in response to low blood volume (as sensed by baroreceptors) or increased blood osmolarity (as sensed by osmoreceptors).

Answer 40

Antidiuretic hormone (ADH)

Question 41

Oxytocin is unusual in the it has a ___________ feedback loop: the release of oxytocin promotes uterine contraction, which promotes more oxytocin release, which promotes stronger uterine contractions, and so on.

Answer 41

Positive feedback

Question 42

The __________ is controlled by thyroid-stimulating hormone from the anterior pituitary.

Answer 42

Thyroid

Question 43

One of the major functions of thyroid is releasing ____________ (T3) and ___________ (T4) to set the basal metabolic rate.

Answer 43

Triiodothyronine (T3), thyroxine (T4)

Question 44

One of the major functions of thyroid is releasing ____________ to promote calcium homeostasis.

Answer 44

Calcitonin

Question 45

Triiodothyronine (T3) and thyroxine (T4) are both produced by the iodination of the amino acid ___________ in the follicular cells of the thyroid.

Answer 45

Tyrosine

Question 46

High plasma levels of thyroid hormones will lead to decreased ____________ and ___________ synthesis; negative feedback prevents excessive secretion of T3 and T4.

Answer 46

Thyroid-stimulating hormone (TSH), thyroid-releasing hormone (TRH)

Question 47

A deficiency of iodine or inflammation of the thyroid may result in ____________.

Answer 47

Hypothyroidism

Question 48

___________ is caused by thyroid hormones deficiency that result in intellectual disability and developmental delay.

Answer 48

Cretinism

Question 49

An excess of thyroid hormone, which may result from a tumour or thyroid over-stimulation, is called _____________.

Answer 49

Hyperthyroidism

Question 50

___________ cells within the thyroid gland produce thyroid hormones.

Answer 50

Follicular cells

Question 51

___________ cells (also called ______________ cells) produce calcitonin.

Answer 51

C-cells, parafollicular cells

Question 52

Calcitonin decreases plasma calcium levels in 3 ways: by ____________ calcium excretion from the kidneys, by ___________ calcium absorption from the gut, and by ____________ storage of calcium in the bone.

Answer 52

increasing, decreasing, increasing

Question 53

The __________ are 4 small pea-sized structures that sit on he posterior surface of the thyroid.

Answer 53

Parathyroids

Question 54

_______________ serves as an antagonist hormone to calcitonin, raising blood calcium levels; specifically, it decreases excretion of calcium by the kidneys, increases absorption of calcium in the gut (via vitamin D), and increases bone resorption, thereby freeing up calcium.

Answer 54

Parathyroid hormone (PTH)

Question 55

As levels of plasma calcium rise, ___________ hormone secretion is decreased.

Answer 55

Parathyroid

Question 56

Parathyroid hormone activates ____________, which is required for the absorption of calcium and phosphate in the gut.

Answer 56

Vitamin D

Question 57

The ___________ secretes corticosteroids.

Answer 57

Adrenal cortex

Question 58

Corticosteroids are steroid hormones that can be divided into 3 functional classes: ___________, ___________, ___________.

Answer 58

Glucocorticoids, mineralocorticoids, and cortical sex hormones

Question 59

____________ are steroid hormones that regulate glucose levels.

Answer 59

Glucocorticoids

Question 60

The 2 most common glucocorticoids are ___________ and ___________.

Answer 60

Cortisol, cortisone

Question 61

___________ is known as a stress hormone because it is released in times of physical or emotional stress. This increases blood sugar and provides a ready source of fuel for the body.

Answer 61

Cortisol

Question 62

_____________ from the hypothalamus promotes release of ____________ hormone from the anterior pituitary, which promotes release of glucocorticoids from the adrenal cortex.

Answer 62

Corticotropin-releasing factor (CRF) Adrenocorticotropic hormone (ACTH)

Question 63

____________ are used in salt and water homeostasis; their most profound effects are on the kidneys.

Answer 63

Mineralocorticoids

Question 64

The most noteworthy mineralocorticoid is ___________, which increases sodium reabsorption in the distal convoluted tubule and collecting duct of the nephron (increasing blood volume + pressure).

Answer 64

Aldosterone

Question 65

Unlike antidiuretic hormone (ADH) that increasing the water reabsorption in the kidney leads to decreasing plasma osmolarity, ___________ allows water and sodium ion to flow together and the plasma osmolarity remains unchanged.

Answer 65

Aldosterone

Question 66

___________ deceases the reabsorption of potassium and hydrogen ions in the distal convoluted tubule and collecting duct of the nephron, promoting their excretion in the urine.

Answer 66

Aldosterone

Question 67

Unlike the glucocorticoids, aldosterone is primarily under the control of the ________________ system.

Answer 67

Renin-angiotensin-aldosterone system

Question 68

Decreased blood pressure causes the _______________ of the kidney to secrete renin, which cleaves an inactive plasma protein, angiotensinogen, to its active form, angiotensin I.

Answer 68

Juxtglomerular cells

Question 69

The active form angiotensin I is converted to angiotensin II by ______________ in the lungs.

Answer 69

Angiotensin-converting enzyme (ACE)

Question 70

______________ stimulates the adrenal cortex to secrete aldosterone.

Answer 70

Angiotensin II

Question 71

Once blood pressure is restored, there is a decreased drive to stimulate ________ release, thus serving as the negative feedback for the renin-angiotensin-aldosterone system.

Answer 71

Renin

Question 72

The adrenal glands make cortical sex hormones (including __________ and ___________)

Answer 72

Androgen Estrogen

Question 73

___________ is responsible for the production of epinephrine and norepinephrine.

Answer 73

Adrenal medulla

Question 74

__________ is understood to mediate long-term (slow) stress response. It also increases the synthesis of catecholamines as well, resulting in an increase in catecholamine release.

Answer 74

Cortisol

Question 75

From the endocrine standpoint, small clusters of hormone-producing cells are grouped together into ____________ throughout the pancreas.

Answer 75

Islets of Langerhans

Question 76

Islets contain distinct types of cells: __________, _________, and __________ cells.

Answer 76

Alpha Beta Delta

Question 77

From the exocrine standpoint, acinar cells secrete digestive enzymes into pancreatic _________.

Answer 77

Duct

Question 78

Alpha cells of the islets of Langerhans secrete __________ (hormone).

Answer 78

Glucagon

Question 79

Beta cells of the islets of Langerhans secrete ___________ (hormone).

Answer 79

Insulin

Question 80

Delta cells of the islets of Langerhans secrete ____________ (hormone).

Answer 80

Somatostatin

Question 81

___________ is secreted during times of fasting. When glucose levels are low, it increases glucose production by triggering glycogenolysis, gluconeogenesis, and the degradation of protein and fat.

Answer 81

Glucagon

Question 82

____________ is antagonistic to glucagon and is therefore secreted when blood glucose levels are high.

Answer 82

Insulin

Question 83

In excess, insulin will cause _____________, which is characterized by low blood glucose concentration.

Answer 83

Hypoglycemia

Question 84

Underproduction, inefficient secretion, or insensitivity to insulin can result in _____________, which is clinically characterized by hyperglycaemia (excess glucose in the blood).

Answer 84

Diabetes mellitus

Question 85

Diabetes often report ___________ (increased frequency of urination) and __________ (increased thirst).

Answer 85

Polyuria Polydipsia

Question 86

___________ (insulin-dependent) diabetes mellitus is caused by autoimmune destruction of the beta cells of the pancreas, resulting in low or absent insulin production. It requires regular injections of insulin to prevent hyperglycaemia and to permit uptake of glucose into cells.

Answer 86

Type I

Question 87

___________ (non-insulin-dependent) diabetes mellitus is the result of receptor-level resistance to the effects of insulin. It is partially inherited and partially due to environmental factors, such as high carbohydrate diets and obesity.

Answer 87

Type II

Question 88

_______________ hormones can raise blood glucose levels. Examples are growth hormone, glucocorticoids, and epinephrine.

Answer 88

Counterregulatory hormones

Question 89

____________ is an inhibitor of both insulin and glucagon secretion. High blood glucose and amino acid concentrations stimulate its secretion.

Answer 89

Somatostatin

Question 90

____________ is produced by the hypothalamus, where it decreases growth hormone secretion in addition to its effects on insulin and glucagon.

Answer 90

Somatostatin

Question 91

The ___________ secrete testosterone in response to stimulation by gonadotropins (luteinizing hormone and follicle-stimulating hormone).

Answer 91

Testes

Question 92

_____________ causes sexual differentiation of the male during gestation and also promotes the development and maintenance of secondary sex characteristics in males, such as axillary and pubic hair, deepening of the voice, and muscle growth.

Answer 92

Testosterone

Question 93

The ___________ secrete estrogen and progesterone in response to gonadotropins.

Answer 93

Ovaries

Question 94

___________ is involved in development of the female reproductive system during gestation and also promotes the development and maintenance of secondary sex characteristics in females, such as axillary and pubic hair, breast growth, and body fat redistribution.

Answer 94

Estrogen

Question 95

The _________ gland is located deep within the brain, where it secretes the hormone melatonin.

Answer 95

Pineal gland

Question 96

It is hypothesized that the pineal gland responds to decreases in light intensity by releasing ____________.

Answer 96

Melatonin

Question 97

The kidneys produce _____________, which stimulates bone marrow to increase production of erythrocytes (red blood cells). It is secreted in response to low oxygen levels in the blood.

Answer 97

Erythropoietin

Question 98

The heart releases ____________ peptide to help regulate salt and water balance. It is released when cells in the atria are stretched from excess blood volume.

Answer 98

Atrial natriuretic peptide (ANP)

Question 99

The thymus, located directly behind the sternum, releases ____________, which is important for proper T-cell development and differentiation.

Answer 99

Thymosin