Endocrine System Flashcards
Where does the endocrine system secrete hormones to maintain homeostasis?
Into the blood.
What are hormones?
Chemical messengers that regulate many body functions. They bind with a specific receptor.
Endocrine cells are located in a gland or gland-like structure.
Target cells have hormone receptors.
Lock and key mechanism.
What are the main endocrine organs?
Pituitary gland- brain
Hypothalamus- brain
Thyroid gland- neck
Adrenal glands- on top of kidney
Pineal gland- brain
Parathyroid glands- neck, posterior part of thyroid
Pancreas- abdomen
What are the organs with secondary endocrine functions?
- Heart
- Thymus
- Adipose tissue
- Digestive tract
- Kidneys
- Gonads (testes and ovaries)
The hypothalamus integrates neural and endocrine activities via what three mechanisms?
- Acts as an endocrine organ- releases ADH (antidiuretic hormone) and OXT (oxytocin)
- Secretes regulatory hormones- control the anterior lobe of the pituitary gland. Regulatory hormones reach their targets by the hypophyseal portal system.
- Contains autonomic nervous system centers- controls hormone secretion in the adrenal gland
What are the five cell types in the anterior lobe of the pituitary gland?
- Thyrotropes- thyroid gland
- Corticotopes- adrenal cortex
- Gonadotropes- reproductive organs
- Lactotropes- mammary glands
- Somatotropes- growth of the body
What is the function of TSH (thyroid-stimulating hormone)?
Targets the thyroid gland to release T3 and T4.
What is the function of adrenocorticotropic hormone (ACTH)?
Targets the adrenal cortex. Stimulates glucocorticosteroid secretion.
What is the function of follicle stimulating hormone (FSH) and luteinizing hormone (LH)?
FSH- targets follicular cells in the ovaries of females and nurse cells in the testes of males. FSH stimulates follicle development and estrogen secretion in females and sperm maturation in males.
LH- targets follicular cells in the ovaries of females and interstitial cells in the testes of males. In females, LH stimulates ovulation, corpus luteum formation, and progesterone secretion.
What is the function of prolactin (PRL)?
Targets the female mammary glands and stimulates milk production.
What is the function of growth hormone (GH)?
Targets all cells in the body. Stimulates growth, protein synthesis, lipid mobilization, and catabolism.
What is the purpose of melanocyte-stimulating hormone (MSH)?
Targets melanocytes. It stimulates increased melanin production in the epidermis.
The Posterior Lobe of the Pituitary Gland
Neurohypophysis
Releases neurosecretions (made by the hypothalamus):
- ADH (antidiuretic hormone)
- OXT (oxytocin)
What is the purpose of ADH (antidiuretic hormone)?
Also known as vasopressin. Targets the kidneys. Promotes the reabsorption of water and elevation of both blood volume and blood pressure.
What is the purpose of oxytocin (OXT)?
Oxytocin targets the uterus and mammary glands in females. It causes labor contractions and milk ejection.
In males, oxytocin targets the ductus deferens and prostate. This causes contractions of the ductus deferens and prostate and ejection of secretions.
How are T3 and T4 released? What functions do they serve?
Hypothalamus releases TRF (thyrotropin releasing factor). This acts on anterior pituitary, which releases thyroid stimulating hormone. TSH circulates in the blood and is picked up by the thyroid gland, which produces triiodothyronine (T3) and thyroxine (T4).
T3 and T4 are primarily responsible for regulation of metabolism.
Calcitonin produced by the thyroid gland decreases blood calcium levels.
Where are the parathyroid glands located?
4 total, located on the posterior surface of the thyroid gland.
What are the two major types of cells associated with the parathyroid glands?
- Parathyroid cells (principal cells)
- Respond to low Ca levels by releasing parathyroid hormone. - Oxyphil cells
Where do the adrenal glands sit?
On top of each kidney.
What are the parts of the adrenal gland?
Adrenal cortex (outer portion) and adrenal medulla (inner portion).
What does the adrenal medulla release as part of the sympathetic nervous system response?
Epinephrine (adrenaline) and norepinephrine (noradrenaline)
What does the adrenal cortex release?
Cortisol- corticosteroid- increases blood sugar, stress
ALDOSTERONE- PROMOTES WATER RETENTION
Androgens- sex hormones
- Targets liver to synthesize glucose and glycogen
- Suppresses immune system (reduce joint swelling)
- Stabilizes BP through Na and H2O balance
- Testosterone- small quantities here in both sexes
The pancreas functions as both a ________?
Exocrine and endocrine structure.
What are the functions of the pancreas?
Exocrine function: Produces digestive enzymes
Endocrine function:
- Consists of pancreatic islets
- Produces hormones
