endocrine system Flashcards
define endocrine signaling
Endocrine signaling is a form of intercellular communication in which hormones are released by endocrine glands into the bloodstream to regulate distant target cells or organs
name the four processes that the endocrine system co-ordinate
- metabolism
- growth and development
- reproduction
- stress response
describe the differences between an endocrine and exocrine gland
- Endocrine Glands:
- Structure: ductless glands that secrete hormones directly into the bloodstream. highly vascularized and composed of clusters of hormone-secreting cells
- Function: produce hormones that act as chemical messengers, regulating various physiological processes in the body (metabolism, growth, reproduction, and stress response)
Examples: pituitary gland, thyroid gland, adrenal glands, pancreas, and gonads (ovaries and testes). - Exocrine Glands:
- Structure: have ducts that transport their secretions to a body surface or cavity. clusters of secretory cells arranged around ducts lined with epithelial cells. may be simple or complex
- Function: secrete substances such as enzymes, mucus, sweat, saliva, and digestive juices (digestion, lubrication, protection, and thermoregulation)
Examples: salivary glands, sweat glands, sebaceous glands (oil glands), mammary glands, liver (which produces bile), and pancreas (which produces digestive enzymes).
name three full endocrine glands
pituitary gland
thyroid gland
adrenal gland
name three partial endocrine glands
pancreas
pineal gland
parathyroid gland
define a hormone
A hormone is a chemical substance produced by endocrine glands or specialized cells in the body that acts as a signaling molecule to regulate various physiological processes and maintain homeostasis.
describe how a hormone changes the behaviour of its target cell
- Recognition and Binding: The hormone travels through the bloodstream and reaches its target cells. Once at the target cell, the hormone binds to its specific receptor with high affinity and specificity. Each hormone has a unique receptor
- Activation of Signal Transduction Pathways:
- Surface Receptors: If the hormone receptor is located on the cell surface, binding of the hormone triggers a signal transduction pathway. This activates a second messenger molecule which relay the hormonal signal from the receptor to the cell interior.
- Intracellular Receptors: If the hormone receptor is located within the cell hormone binding leads to conformational changes in the receptor protein - Alteration of Cellular Function:
- Activation of Gene Expression: In the case of intracellular receptors, hormone-receptor complexes bind to specific DNA sequences in the nucleus, regulating the transcription of target genes. This results in the synthesis of new proteins or mRNA molecules that alter cellular function over longer time periods.
- Modulation of Enzyme Activity and Metabolic Pathways: Hormone-induced activation of second messenger pathways or other intracellular signaling cascades can lead to rapid changes in cellular function. This may involve the activation or inhibition of enzymes, alteration of ion channel activity, or changes in the phosphorylation status of proteins, ultimately influencing cellular metabolism, secretion, contraction, or other physiological processes. - Response and Adaptation: The changes induced by hormone binding result in a cellular response that adapts the target cell’s behavior to meet physiological needs.
name the three classes of hormones
peptide and protein hormones
steroid hormones
amino acid-derived hormones
what are the two endocrine structures in the diencephalon
hypothalamus
pineal gland
how is the hypothalamus linked to the pituitary gland and what does it control
the hypothalamus is linked through critical axis, the hypothalamic-pituitary axis (HPA) or the hypothalamic-pituitary portal system - it regulates the secretion of hormones from the pituitary gland
describe the anterior pituitary gland hormones, their effect and their stimulus
- Adrenocorticotropic Hormone:
- Effect: Stimulates the adrenal cortex to release cortisol
- Stimulus: corticotropin-releasing hormone (CRH) from the hypothalamus in response to stress and low blood cortisol levels. - Thyroid-Stimulating Hormone:
- Effect: Stimulates the thyroid gland to produce thyroid hormones to regulate metabolism, growth, and development.
- Stimulus: thyrotropin-releasing hormone (TRH) from the hypothalamus in response to low thyroid hormone levels in the blood. - Follicle-Stimulating Hormone:
- Effect: In females - growth and development of ovarian follicles and promotes estrogen secretion. In males - spermatogenesis (sperm production) in the testes.
- Stimulus: gonadotropin-releasing hormone (GnRH) from the hypothalamus and inhibited by negative feedback from sex hormones (estrogen and testosterone). - Luteinizing Hormone:
- Effect: In females, ovulation and stimulates the formation of the corpus luteum (progesterone) In males, Leydig cells in the testes to produce testosterone.
- Stimulus: gonadotropin-releasing hormone (GnRH) from the hypothalamus and inhibited by negative feedback from sex hormones (estrogen and testosterone). - Prolactin:
- Effect: milk production (lactation) in the mammary glands of the breasts.
- Stimulus: inhibited by dopamine (prolactin-inhibiting hormone) from the hypothalamus or estrogen, suckling, and stress can also influence prolactin secretion. - Growth Hormone:
- Effect: growth, cell proliferation, and protein synthesis in various tissues and organs. regulates metabolism and energy balance.
- Stimulus: growth hormone-releasing hormone (GHRH) and somatostatin (growth hormone-inhibiting hormone) from the hypothalamus and sleep, exercise, stress, and nutrition.
what is the function of oxytocin
- uterine contraction
- milk ejection (letdown reflex)
- social bonding and attachment
- stress reduction
whats another name for vasopressin and what is its role in the kidney
antidiuretic hormone (ADH)
regulates water balance and maintains proper fluid and electrolyte levels through:
1. water reabsorption
2. concentration of urine
3. regulation of blood pressure
what do the thyroid hormones regulate
- metabolism
- energy production and utilization
- growth and development
- regulation of body temperature
- cardiovascular function
explain how the pancreas acts as both an endocrine and exocrine gland
- Endocrine Function:
- Islets of Langerhans: contain several types of hormone-secreting cells
a. Beta Cells: produce and secrete insulin
b. Alpha Cells: produce and secrete glucagon
c. Delta Cells: produce somatostatin
d. PP Cells: produce pancreatic polypeptide
Hormone Release: released directly into the bloodstream - regulate metabolism, energy balance, and nutrient utilization throughout the
body. - Exocrine Function:
a. Acinar Cells: produce and secrete digestive enzymes and fluids into a network of ducts that ultimately empty into the duodenum
b. Digestive Enzymes: amylase (for carbohydrate digestion), lipase (for fat digestion), and proteases (for protein digestion).
c. Bicarbonate Secretion: alkaline fluid that helps to neutralize the acidic chyme (partially digested food) from the stomach
