Which of the following hormones stimulates the adrenal cortex to release glucocorticoids

BIO 308
Human Anatomy and Physiology II

Endocrine System (Glands and Hormones - Hormone Cascades)

Two types of glands: exocrine (secrete directly into or onto something) and endocrine (secrete hormones into the blood).

Exocrine glands include salivary glands, sweat glands, sebaceous (oil) glands, and glands in the digestive system

Hormones:

• Chemical messengers transported in the blood that regulate the activities of distant cells and other organs.
• Only cells sensitive to particular hormones are affected by those hormones
• Bond to specific receptors of cells (proteins) in target tissues and glands
• Most hormones can placed into three chemical categories: steroids, monoamines, and peptides

  Steroid hormones - derived from cholesterol and include sex steroids produced in the ovaries and testes (e.g., estrogen, progesterone, and testosterone) and corticosteroids produced by the adrenal gland (e.g., cortisol)

  Monoamines - made from amino acids and include epinephrine, norepinephrine, and thyroid hormones

  Peptide hormones - also made from amino acids and include oxytocin, antidiuretic hormone, and insulin

Endocrine glands

Hypothalamus:

• produces six hormones to regulate the anterior pituitary plus oxytocin and antidiuretic hormone that are stored and released from the posterior pituitary
• releasing hormones - stimulate the anterior pituitary to release hormones:
  • Thyrotropin-releasing hormone (TRH) - promotes secretion of thyroid-stimulating hormone (TSH) and prolactin (PRL)
  • Corticotropin-releasing hormone (CRH) - promotes secretion of adrenocorticotropic hormone (ACTH)
  • Gonadotropin-releasing hormone (GRH) - promotes secretion of follicle-stimulating hormone (FSH) and luteinizing hormone (LH)
  • Growth-hormone releasing hormone (GHRH) - promotes secretion of growth hormone (GH)
• inhibiting hormones - suppress secretion of hormones by the anterior pituitary:
  • Prolactin-inhibiting hormone (PIH) - inhibits secretion of prolactin
  • Somatostatin - inhibits secretion of growth hormone (GH) and thyroid-stimulating hormone (TSH)

 

Pituitary gland – two lobes: anterior pituitary and posterior pituitary

TSH – thyroid stimulating hormone, ACTH – adrenocorticotropic hormone, FSH – follicle stimulating hormone, and LH – luteininizing hormone

Anterior pituitary hormones:

• Growth Hormone (GH):
  • stimulates mitosis and cellular differentiation to promote body growth
  • not targeted to just one or a few organs; has widespread effects on the body
  • most pronounced effects of GH are on bone, cartilage, and skeletal muscle during childhood and adolescence
  • GH levels in the blood decline with age
• Follicle Stimulating Hormone (FSH) - stimulates secretion of ovarian sex hormones and promotes follicle development in ovaries and maturation of sperm in testes
• Lutenizing Hormone (LH) - induces ovulation in females and promotes estrogen and progesterone secretions and stimulates production of sex hormones in males
• Adrenocorticotrophic Hormone (ACTH) – stimulates the adrenal glands to release glucocorticoids.
• Prolactin – stimulates milk production by the mammary glands
• Thyroid Stimulating Hormone (TSH) – stimulates the thyroid gland to produce thyroid hormones (thyroxine and triiodothyronine)

Target organs help regulate the pituitary and hypothalamus through feedback loops (most often, negative feedback loops). For example:

Example of negative feedback inhibition. Such feedback helps maintain appropriate levels of hormones in the blood.
T3, triiodothryonine; T4, thyroxine; TRH, Thryotropin-releasing hormone; TSH, Thyroid-stimulating hormone

Posterior pituitary hormones:

• Oxytocin – produced in the hypothalamus and stored in the posterior lobe of the pituitary gland. Released prior to giving birth; stimulates contractions of the uterus and is also important in secretion of milk by the mammary glands.
• Antidiuretic Hormone (ADH) – produced in the hypothalamus and stored in the posterior lobe of the pituitary gland, causes kidneys to reabsorb water

Positive feedback - oxytocin and the uterus

Thyroid gland:

• Thyroid Stimulating Hormone (TSH) – stimulates the thyroid to produce triiodothyronine and thyroxine, hormones that regulate basal metabolic rates (rate at which our cells use energy).
  • thyroid hormones:
    • increase the body's metabolic rate via increased oxygen consumption
    • increase respiratory rate and heart rate to ensure adequate blood and oxygen supply
    • stimulates appetite and speeds up the breakdown of carbohydrates, fats, and proteins
    • promotes alertness and enhances reflexes
• Calcitonin – stimulates bones to absorb calcium from the blood, works to oppose Parathyroid Hormone (PTH)

Parathyroid gland: causes bones to release calcium into the blood to increasing blood calcium levels.

Calcitonin - Parathyroid hormone feedback loop

Calcitonin stimulates osteoblasts (depositing more calcium in bone);
Parathryoid hormone stimulates osteoclasts (releasing calcium from bone)

 

Adrenal glands:

Adrenal cortex hormones:

• Glucocorticoids
• Hydrocortisone or cortisol:
  • released during periods of stress, increases blood glucose, suppresses immune system, and aids in metabolism of proteins, fats, and carbohydrates
  • also have an anti-inflammatory effect (hydrocortisone is used to relieve swelling and other side effects of inflammation)
• Mineralcorticoids
• Aldosterone – helps regulate blood pressure by signaling kidneys to retain ions and water.and increase blood volume
• Sex hormones
• Testosterone – male sex hormone (in small amounts)
• Estrogen – female sex hormone (in small amounts)

Adrenal medulla:

• releases hormones that increase cardiac output, mental alertness, respiratory rate and metabolic rate, preparing the body to cope with mental/physical stress.
• Norepinephrine - stress hormone & neurotransmitter, causes increased attention and higher blood pressure
• Epinephrine – also called adrenalin’ the ‘fight or flight’ hormone that causes an increased heart rate, increased cardiac output, increased respiratory rate, and increased blood flow to skeletal muscles and the central nervous system

Pancreas:

Glucagon – increases blood glucose levels by stimulating liver cells to break down glycogen into glucose and release it into the blood

Insulin – decreases blood glucose levels by stimulating cells to absorb blood glucose.

Effect of insulin on glucose uptake and metabolism. Insulin binds to its receptor (1), which activates a process that includes
translocation of glucose transporters to the cell membrane and an influx of glucose (3), followed by glycogen synthesis (4),
glycolysis (5) and triglyceride synthesis (6).

 

Gonads – testes and ovaries

Testes:

Follicle-stimulating hormone - stimulates spermatogenesis in seminiferous tubules of the testes

Luteinizing hormone - stimulates production of testosterone by Leydig cells in the testes

• Testosterone - primary and secondary sexual characteristics, skeletal muscle anabolism, libido, and increased bone density

 

Ovaries:

Estrogen – secondary sexual characteristics and regulation of the menstrual cycle

Progesterone – plays a role in maintaining pregnancy, helps prepare the uterus for pregnancy, and regulates the monthly menstrual cycle.

 

Review questions:

Know the difference between exocrine and endocrine glands. What are hormones and how do they affect the activity of target tissues and glands? What hormones are produced by the hypothalamus? Know the general functions of GH, FSH, LH, ACTH, prolactin, and TSH. What are the general functions of oxytocin and antidiuretic hormone? What are the functions of thyroid stimulating hormone and calcitonin? How do calcitonin and parathyroid hormone interact to regulate calcium levels in the blood? What hormones are produced by the adrenal cortex and what are their general functions? What hormones are produced by the adrenal medulla and what are their general functions? What hormones are produced by the pancreas and what are their functions? What hormones are produced by the testes and ovaries and what are their functions?

Review questions - Video: Hormones of the hypothalamus and pituitary gland:

What is the pituitary sometimes called the master gland? Which lobe of the pituitary is actually an extension of the hypothalamus? Why is the hypothalamus sometimes referred to as the master controller? Know that you can remember the names of the hormones produced by the pituitary using the acronym 'GOAT FLAP.' Which hormone is referred to with each letter in the acronym 'GOAT FLAP?'

Review questions - Video: Blood calcium regulation:

Why is calcium important in the body?

Review questions - Video: Hormonal regulation of male reproduction:

What hormone is produced by the testes in response to LH? What are the various effects of testosterone in males? Know that FSH stimulates spermatogenesis in the testes.

Review questions - Video: The menstrual cycle 3D animation:

What is the function of FSH in ovaries? What results from a sudden increase in LH production? What hormone is produced by the corpus luteum? What is the endometrium? What happens during the follicular phase of the menstrual cycle? What happens to the endometrium after ovulation (the luteal phase)? What happens if the egg is not fertilized? What happens if the egg is fertilized?

What stimulates the release of glucocorticoids from the adrenal cortex?

What hormone stimulates glucocorticoid?

Which of the following hormones stimulates the adrenal cortex to release?

Which of the following hormones stimulates the adrenal cortex to release glucocorticoids that help the body to resist stressors quizlet?