MCAT Biology Endocrine System Flashcards
The ___is part of the sympathetic nervous system releasing epinephrine and norepinephrine into the blood when stimulated
Adrenal medulla
A tropic hormone produced by the anterior pituitary gland that targets the adrenal cortex, stimulating it to release cortisol and aldosterone
Adrenocorticotropic Hormone (ACTH)
ACTH is produced by the ___
anterior pituitary gland
ACTH target the __
adrenal cortex to release cortisol and aldosterone
Also known as the adenohypophysis
Anterior pituitary gland
FSH, LH, ACTH, TSH, Prolactin, and growth hormone are all produced and secreted by the
Anterior pituitary gland
The anterior pituitary is controlled by releasing and inhibiting factors from the ___
hypothalamus
Also called vasopressin
Antidiuretic hormone (ADH)
This hormone is produced in the hypothalamus and secreted by the posterior pituitary gland. It targets the kidney tubules, increasing the permeability to water, and thus increasing water retention by the body
Antidiuretic hormone (ADH)
A hormone produced by the C-cells of the thyroid gland that DECREASE serum calcium levels
Calcitonin
__targets the bones (stimulates osteoblasts) and the kidneys (reduces calcium reabsorption)
Calcitonin
___ is the principal mineralcorticoid
Aldosterone
___is the principle glucocorticoid
Cortisol
___are steroid hormones secreted from the adrenal cortex
Corticosteroids
This steroid hormone is released during times of stress, increasing blood glucose levels and reducing inflammation
Cortisol
A ductless gland that secretes a hormone into the blood
Endocrine gland
A gland that secretes its product into a duct, which ultimately carries the product to the surface of the body or into a body cavity. Some examples include:
- sweat glands (sweat)
- Gastric glands (acid,mucus, protease)
- Liver (bile)
- Sebaceous glands (oil)
- Lacrimal glands (tears)
Exocrine glands
A hormone release by the anterior pituitary that targets all cells in the body.
Growth hormone
___ stimulates whole body growth in children and adolescents, and increases cell turnover rate in adults
Growth hormone
A set of veins that connect a capillary bed in the hypothalamus (the primary capillary plexus) with the capillary bed in the anterior pituitary gland ( the secondary capillary plexus).
Hypothalamic-pituitary portal system
Releasing and inhibiting factors from the hypothalamus travel along veins directly affect the cells in the anterior pituitary gland by way of ___
hypothalamic-pituitary portal system
The portion of the diencephalon involved in maintaining body homeostasis
Hypothalamus
The __controls release of hormones from the pituitary gland
Hypothalamus
A form of regulation in which the end result of a series of events inhibits the trigger for that series
Negative feedback
Hormones are generally regulated via__
negative feedback
Insulin is released when blood glucose levels rise. IT causes the cells of the body to take glucose out of the blood, leading to a drop in glucose levels. The fall in glucose levels stops insulin release
Negative feedback
Neurohypophysis =
Posterior pituitary gland
A hormone made of amino acids __
peptide hormone
__ are generally hydrophilic and cannot cross the plasma membranes of cells, thus the receptor for them must be found on the cell surface
Peptide hormones
Binding of a ___ to its receptor usually triggers a second messenger system within the cell
Peptide hormone
Which peptide hormone has its receptor on the interior of the cell?
Thyroxine which is hydrophobic enough to enter the cell easily
The ___ is made of nervous tissue and stores and secretes two hormones made in the hypothalamus
Posterior pituitary gland
The posterior pituitary gland is controlled by action potentials from the ___
hypothalamus
The hypothalamus makes __ and___ which are stored in the posterior pituitary gland
Oxytocin and ADH
A hormone derived from ___
cholesterol
___ are generally hydrophobic and can easily cross the plasma membranes of cells, thus receptors for them are found intracellularly
Steroid hormone
Once the ___ binds to its receptor, the complex acts to regulate transcription in the nucleus
Steroid hormone
A tropic hormone produced by the anterior pituitary gland that targets the thyroid gland, stimulating it to produce and release thyroid hormone
Thyroid stimulating hormone (TSH)
__ is produced and secreted by follicle cells in the thyroid gland.
Thyroxine (thyroid hormone)
____targets all cells in the body and increases overall body metabolism
Thyroxine
A hormone that controls the release of another hormone
Tropic hormone
If signaling molecules modify the activity of the cells which secreted them this is ___
autocrine activity
T cell secretes interleukin 2, which binds to receptors on the same T cell to stimulate increased activity
Autocrine activity
The hydrophilicity of peptide hormones means they can’t cross the biological membrane and thus are required to communicate with the interior of the target cell by way of a __
second messenger cascade
The two subgroups of peptide hormones are __ and _
polypeptides and amino acid derivatives
An example of a polypeptide hormone is __
insulin
___is secreted by the beta cells of the pancreatic islets of Langerhans in response to elevated blood glucose
Insulin (polypeptide hormone)
___ are derived from single amino acids and contain no peptide bonds
Amino acid derivatives (hormones)
___ is the parent amino acid for the catecholamines (which include epinephrine) and the thyroid hormones
Tyrosine
___ incorporate iodine into their structure. enter the cell, bind to DNA, and activate transcription of genes involved in energy mobilization
Thyroid hormones
___ are hydrophobic molecules synthesized from cholesterol in the smooth endoplasmic reticulum
Steroids
The small hydrophobic steroid hormones exert their effects upon target cells by ___
diffusing through the plasma membrane to bind with a receptor in the cytoplasm
Because peptide hormones modify the activity of existing enzymes in the cytoplasm their effects are exerted___
rapidly minutes to hours from time of secretion
Because steroid hormones must be transported as a steroid hormone-receptor complex into the nucleus and modify transcription to change the amount and/or type f proteins in the cell, their effects are exerted__
slowly, over a period of days, and persist for days to weeks
Steroids regulating water balances and other processes are secreted by the ___
adrenal cortex
Regulation of release of peptide hormones?
Stored in vesicles until a signal for secretion is received
Mechanism of effect of peptide hormones?
Bind to receptors that generate second messengers which result in modification of enzyme activity
Site of synthesis of steroid hormones
Smooth ER
Regulation of release of steroid hormones?
Synthesized only when needed and then used immediately, not stored
The function of calcitonin is to ___
prevent serum [Ca2+] from peaking above normal levels, and the amount of calcitonin secreted is directly proportional to increases in serum [Ca2+] above normal.
When serum [Ca2+] is elevated, ___
calcitonin is secreted
