UNIT 6 - Endocrine system II - select glands

Question 1

Thyroid gland

Answer 1

Location:
●In the anterior neck, inferior to the larynx.

●Made up of two connected lobes lying on either side of the trachea.

Question 2

Thyroid gland - structure

Answer 2

●Consists of numerous thyroid follicles, which are round structures that make and store T3 and T4.

●Follicles are surrounded by parafollicular cells, which make calcitonin.

Question 3

Thyroid gland - hormones 2

Answer 3

1- Triiodothyronine T3 and Thyroxine T4

2- Calcitonin

Question 4

Triiodothyronine T3 and Thyroxine T4 - Hormone of the thyroid gland

Answer 4

Target: Most body cells

Actions:
▪ Increases metabolic rate
▪ Essential for tissue growth and development (esp. of skeletal, nervous, and reproductive systems)

Question 5

Calcitonin - Hormone of the thyroid gland

Answer 5

Target: skeleton (bone tissue)
Action: Lowers blood calcium (Ca2+) levels.

How?
by stimulating osteoblast activity &
by inhibiting osteoclast activity.

Question 6

Parathyroid gland

Answer 6

▪ Location
Four small, rounded glands on the posterior surface of the thyroid gland.

▪ Function
Secretes parathyroid
hormone (PTH).

Question 7

Parathyroid gland

Answer 7

Parathyroid Hormone (PTH):
Targets: bone, kidney, intestine
Actions: Increases blood Ca2+ levels by:

◦ stimulating osteoclast activity
◦ stimulating kidneys to reabsorb more Ca2+ (decreases Ca2+ lost in urine)

◦ stimulating intestine to absorb Ca2+

Question 8

Pancreas

Answer 8

▪ Location - posterior to stomach; extends from duodenum to spleen.

▪ Structure - composed of
soft lobular tissue with clusters of endocrine cells called pancreatic islets or islets of Langerhans interspersed in exocrine tissue.

Question 9

Hormones secreated by pancreas

Answer 9

Insulin
Glucagon

Question 10

Insulin

Answer 10

Targets: Most cells, but especially

Actions: Decreases blood glucose levels by:
◦ promoting uptake and utilization of glucose by cells

◦ promoting the storage of glucose as glycogen (glycogenesis)
◦ promoting conversion of glucose to fat

   ▪ Secreted by beta (β) cells within the islets.

Question 11

Glucagon

Answer 11

Target: Liver
Actions: Increases blood glucose levels by:
◦ stimulating breakdown of glycogen to glucose (glycogenolysis)

◦ promoting gluconeogenesis (formation of new glucose from non-carbohydrate sources)
- Secreted by alpha (α) cells within the islets.

Question 12

Adrenal Gland

Answer 12

Location:
Two glands that sit just above each kidney

Structure:
- Roughly pyramid shaped with an outer cortex and an inner medulla.
- The cortex and medulla function as separate glands.

Question 13

Adrenal cortex

Answer 13

●Composed of glandular epithelium.
●Regulated by ACTH from anterior pituitary and humoral mechanisms, such as concentration of sodium and potassium in blood.

●Secretes three classes of corticosteroids:
1. mineralocorticoids
2. glucocorticoids
3. gonadocorticoids

Question 14

Corticosteroids of adrenal cortex: Mineralocorticoids (Aldosterone)

Answer 14

Mineralocorticoids

Target: Kidney

Actions: Aldosterone stimulates the kidneys to:
◦ reabsorb sodium (Na+) and water
◦ excrete potassium (K+)
Overall, this hormone:
◦ Increases blood volume & blood pressure
◦ aids in sodium & potassium balance

What might trigger secretion of this hormone?
A decrease in blood pressure.

Question 15

Corticosteroids of adrenal cortex - glucocorticoids (cortisol).

Answer 15

▪ Release is stimulated by ACTH from the anterior pituitary.

Target: most cells

Actions:
▪ increases blood glucose by stimulating gluconeogenesis.
At excessive levels:
▪ inhibits inflammation and immune responses

Question 16

Corticosteroids of adrenal cortex - gonadocorticoids ( androgens & estrogens)

Answer 16

●The amounts secreted are much lower in comparison to the amounts secreted by the ovaries or testes.
●May play a role in onset of puberty and sex drive.

*Androgens = male sex hormones; ex. testosterone

Question 17

Adrenal Medulla

Answer 17

●Derived from the same fetal tissue as the nervous system.

●Regulated directly by nerve stimulation from the sympathetic nervous system.

●Secretes epinephrine and norepinephrine (the catecholamines) which, along with the sympathetic nervous system, trigger the “fight-or flight” response.

Question 18

Adrenal Medulla

Answer 18

●Derived from the same fetal tissue as the nervous system.

●Regulated directly by nerve stimulation from the sympathetic nervous system.

●Secretes epinephrine and norepinephrine (the catecholamines) which, along with the sympathetic nervous system, trigger the “fight-or flight” response.

●These hormonal effects of the catecholamines last about 10 times longer than the effects of sympathetic nervous system alone.

Question 19

Adrenal Medulla

Answer 19

Primary Actions of Catecholamines:
▪ Dilate vessels supplying cardiac & skeletal muscle.

▪ Increase:
blood glucose, heart rate, blood pressure, mental alertness, respiratory and metabolic rates.

Question 20

Pineal gland:

Answer 20

▪ Located in posterior diencephalon.
▪ Secretes melatonin
▪ Melatonin targets the hypothalamus and makes us drowsy, thus helping to induce sleep.

▪ Overall, helps regulate daily rhythms such as sleep and wakefulness.

Question 21

Testies

Answer 21

●Located in scrotum.
●Secrete testosterone.

Actions of testosterone:

▪ Promotes maturation &
maintenance of male reproductive organs and secondary sex characteristics.
▪ Involved with sperm production (spermatogenesis).

Question 22

Ovaries

Answer 22

• Located in pelvic cavity
• Secrete estrogens and progesterone

Estrogens & Progesterone (collectively)
▪ Promote maturation and maintenance of female reproductive organs and secondary sex characteristics.
▪ Help regulate menstrual cycle.
▪ Aid in preparing for & maintaining pregnancy.

Question 23

Heart

Answer 23

• Located in thoracic cavity
• Secretes atrial natriuretic peptide (ANP)
• ANP targets the kidneys and stimulates Na+ and water excretion in the urine.

●Actions: Overall, this hormone:
◦Decreases blood volume & blood pressure.

What might trigger secretion of this hormone?
An increase in blood preassure.

Question 24

Kidney

Answer 24

▪ Located in posterior
abdominal cavity.

▪ Secretes erythropoietin.

▪ Actions: Erythropoietin targets the bone marrow to stimulate red blood cell production.

Question 25

Endocrine disorders

Answer 25

• Pituitary dwarfism -
  hyposecretion of growth hormone in children; characterized by slowed long bone growth.

Question 26

Endocrine disorders - alterations with growth hormone

Answer 26

Gigantism -
hypersecretion of growth hormone in children (when epiphyseal plates are still active); the person becomes abnormally tall.

Question 27

Endocrine disorders - alterations with growth hormone

Answer 27

▪ Acromegaly -
hypersecretion of growth hormone after epiphyseal plates have closed; usually characterized by disproportional enlargement of hands, feet & face, without growth in height.

Question 28

Endocrine disorders - Alterations with ADH

Answer 28

▪ Diabetes insipidus - results from too little antidiuretic hormone; individuals with this disorder suffer from excessive urination and intense thirst.

Question 29

Endocrine disorders - aletrations with thyroid hormones

Answer 29

▪ Congenital hypothyroidism -
too little secretion of T3 & T4 (hypothyroidism) in infants; results in stunted physical growth and cognitive impairment.

Question 30

Endorcine disorders - Alterations with thyroid hormones

Answer 30

Myxedema -
hypothyroidism in adults; symptoms include a low metabolic rate; feeling chilled; constipation; thick, dry skin and puffy eyes; edema; lethargy; and mental sluggishness.

Question 31

Endorcine disorders - Alterations with thyroid hormones

Answer 31

▪ Grave’s disease - autoimmune disease causing hyperthyroidism; symptoms include elevated metabolic rate, sweating, rapid & irregular heartbeat, nervousness, and weight loss.

▪ Goiter – enlarged thyroid gland

Question 32

Alterations with the pancreas - endocrine disorders

Answer 32

▪ Diabetes mellitus
- hyposecretion or hypoactivity of insulin
- characterized by high blood glucose levels
- excess glucose is excreted in the urine

Question 33

Alterations with adrenal cortex - endocine disorders

Answer 33

▪ Addison’s disease - too little glucocorticoids and mineralocorticoids; symptoms include weight loss; decreased plasma glucose and sodium; increased potassium levels; dehydration; and hypotension.

Question 34

Alterations with adrenal cortex - endocrine disorders

Answer 34

▪ Cushing syndrome – too many glucocorticoids; characterized by hyperglycemia (elevated blood glucose levels); losses in muscle & bone mass; water & sodium retention; and hypertension & edema.