Endocrine Flashcards
what is the difference between an exocrine gland and endocrine gland? give an example of each.
Exocrine: they use ducts to pass along their secretions (e.g. in the GI tract)
Endocrine: these are ductless glands whose products are picked up by surrounding capillaries. (e.g. pituitary gland)
What is an auotcrine, paracrine, and endocrine response?
autocrine: released molecule acts on the same type of cell its released from
paracrine: hormone diffuses and acts on surrounding cells
endocrine: enters blood stream to distant target cells
Explain the characteristics of a peptide hormone (made,stored,action, etc) and the types of peptide hormones.
- they are hydrophilic
- due to their hydrophillicty they use 2nd messenger systems and act on pre-existing enzymes
- they are made in the rough ER and stored in vesicles until exocytosis
The two types are polypeptides and catecholamines
Explain the characteristics of a steroid hormone (made,stored,action, etc) and the types of steroid hormones.
- steroids are cholesterol derivatives made in the SMOOTH ER
- they are not stored, but made when needed
- they diffuse out of their secretory cells
- they diffuse into target cells and act on DNA
- they use carrier proteins while in blood but are not biologically active when bound. (dissociate to become active)
- hyrophobic
Thyroid hormone
what is the hormone-serum relationship
hormone: the regulator
serum: the regulated
the serum is whats trying to be controlled
e.g. insulin and glucose
what is a tropic hormone?
hormones that regulate hormones
how is the hypothalamus connected to the pituitary gland (2 ways)
- there is a neural connecting stalk which connects to the posterior pituitary
- there is a special circulatory portal system that connects the hypothalamus to the anterior pituitary
what are portal systems?
portal systems are two consecutive capillary beads which allow for easy communication between two close areas of the body. The hypothalamic pituitary portal system allows the hypothalamus to easily send messages to the pituitary.
What are the adenohypophysis and neurohypophysis?
adeno - anterior pit
neuro - posterior pit
what are neuroendocrine cells?
these are neurons which release hormones into the blood stream. The hypothalamic neurons which send to the posterior pit are neuroendocrine cells
What are the hypothalamic hormones?
- cortisol releasing hormone (CRH)
- thyroid releasing hormone (TRH)
- prolactin releasing hormone (PRH)
- gonadotropin releasing hormone (GnRH)
- growth H releasing H (GHRH)
also inhibiting hormones for growth and prolactin
what are the adenohypophysis hormones?
- ACTH
- TSH
- Prolactin
- FSH
- LH
- GH
what is the only non-tropic anterior pit H?
prolactin
what are the target cells of each anterior pituitary hormone. What is the effect of the tropic hormone.
- ACTH stimulates the adrenal cortex which stimulates the release of cortisol. cortisol is a stress response hormone which mobilizes glycogen and fat stores and increases metabolic activity
- TSH acts on the thyroid gland to release Thyroid hormone. TH controls basal metabolism. when released it increases our metabolic rate. it comes in 2 forms (T3, T4) depending on the amount of iodine molecules attached. Note - it acts on transcription since its a steroid.
- Prolactin acts on the the alveolar (luminal) cells of mammary gland to produce milk for babies (note: oxytocin acts on myoepithelial cells to eject milk)
- FSH
males: acts on sertoli cells to produce sperm and androgen-binding proteins
females: acts on granulosa cells to cause follicular growth - LH
males: acts on leydig cells to produce testosterone which is captured by the androgen binding proteins
females: acts on theca cells to produce testosterone which is converted to estrogen by aromatase - GH stimulates the liver to release IGF-1 which acts on bone
does the TH act on the mitochondria directly?
no, only the nucleus
What hormones are secreted by the posterior pituitary
- Antidiuretic hormone aka vasopressin
- stimulates kidney for water retention - oxytocin
- stimulates muscle cells in breast for milk ejection
- stimulates uterus contraction in labour / parturition
What is calcitonin, what secretes it?
- released by thyroid C cells
- it is a peptide hormone
- regulates calcium levels (decreases them)
parathyroid gland function?
secretes parathyroid hormone (PTH) which stimulates calcium release into the blood (opposes the effect of calcitonin)
what does the adrenal medulla secrete?
extension of the SNS - secretes epinephrine which is responsible for a fast acting stress response.
note: epinephrine is an amino-acid derivative (peptide) hormone.
What occurs during low calcium levels?
PTH will be secreted by the parathyroid
what does the adrenal cortex secrete?
- the mineralocorticoid aldosterone. Aldosterone is released by the angiotensin system. Aldosterone is responsible for salt balance within the blood. It increases sodium reabsorption
- the glucocorticoid cortisol
increases: blood glucose, protein catabolism, etc. - Sex steroids
- adrenal problems can cause masculinization or feminization
all are steroid hormones
what is the thymus?
releases thymosin for T cell development in children
what is the endocrine function of the pancreas?
the endocrine cells of the pancreas are called islets of langerhans.
- Alpha cells: secrete glucagon which increases glycogen breakdown (i.e. increase blood glucose)
- Beta cells: secrete insulin which increases glycogen synthesis (i.e. decreases blood glucose)
- S cells: secrete somatostatin inhibits digestive processes.
what do the testes and ovaries/placenta produce?
testes: testosterone (leydig cells)
ovariess + placenta: estogen and progesterone
what hormone does the heart produce ?????
Atrial Natriuretic Hormone (ANF) which stimulates micturition and drops BP
what kidney hormone stimulates RBC production and bone marrow aid.
erythropoietin
