Endocrine System Flashcards
Hormone
an organic chemical produced by one set of cells that affect a different set of cells
Chemical messengers that influence the metabolism of the recipient cell
Hormone
has a specific organ/origin, and a target organ/gland or organs/Glands
And a specific action
Many hormones are proteins that are coded for by genes and synthesized within the cytoplasm by ribosomes
What happens to synthesized hormones?
they eventually get packaged into vesicles by the Golgi apparatus and secreted at the plasma membrane.
What are the two main categories of hormones
Peptides and steroids
Peptide hormones
can be derived from proteins, peptides, and catecholamines
act relatively quickly but are short lived
Steroid hormones
Derived from cholesterol by a series of metabolic reactions
Act more slowly because it takes time to synthesize new proteins than to activate enzymes that are already present in the cell
Where are steroid hormones stored
Fat droplets in the cytoplasm until their release at the plasma membrane
Which hormone can enter the cell and nucleus freely?
Steroid hormones can enter freely and do NOT need to interact with cell surface receptors
Once inside the cell, steroids bind to receptors and create a hormone complex
The complex activates specific genes that lead to protein synthesis
Which hormone type has a longer sustained effect on metabolism?
Steroid hormones do because the create new proteins for a cells
Endocrine glands
These are ductless and secrete their hormones in the bloodstream to be distributed throughout the body.
Exocrine glands
Have ducts and secrete their contents directly onto epithelial tissue
ex. salivary glands
Primary endocrine glands
Secrete hormones that chemically regulate body functioning
Hypothalamus, pituitary gland, pineal gland, thyroid gland, parathyroid gland, adrenal glands, and pancreas
Secondary Endocrine glands
The heart, kidneys, gonads (testes and ovaries), thymus
negative feedback loop
This functions like a thermostat and is how most hormones are regulated.
Homeostasis has a set-point or range it requires to maintain proper functioning
If something falls below the range, it triggers it to turn on like a thermostat. It will run until it is slightly above optimal range, and then shut off. It will turn on again if the levels detected are below the set-point.
How does ADH use a negative feedback loop?
Its action is dilute blood. Once the blood is dilute, the hypothalamus detects dilute levels and shuts off the release of ADH
positive feedback system
This enhances or increases the amount of hormone that is regulated
Oxytocin works in a positive feedback system during childbirth
Hypothalmus
The part of the brain that regulates the internal environment and homeostasis.
It controls heart rate, body temperature, water balance, and glandular secretions of the pituitary gland
pituitary gland
lies just below the hypothalamus and has an anterior and posterior portion.
Posterior pituitary
connected to the hypothalamus by a stalk-like structure. Overlap between the nervous and endocrine systems – store nuerosecretory - cells that respond to neurotransmitters and produce hormones that are stored in the posterior pituitary
Neurosecretory
nuerons in the hypothalamus that respond to neurotransmitters and produce hormones that are stored in the posterior pituitary.
The hormones pass from the hypothalamus through axons that terminate in the posterior pituitary
What two hormones are stored in the posterior pituitary from the axons endings?
ADH ( antidiuretic hormone also called vasopressin) and oxytocin
ADH
promotes the absorption of water from collecting ducts which receive urine produced by the kidneys
As blood becomes dilute, the hormone is no longer released until it is needed again.
Oxytocin
Made by the hypothalamus and stored in the posterior pituitary
Triggers uterine contractions during labor AND stimulates milk production in mammary glands for nursing
Anterior Pituitary gland
Three tiered relationship between the hypothamlus, anterior pituitary gland, and other endocrine glands
They hypothalamus produces hormones that travel to the APG, and then trigger the APG to make specific hormones that control the thyroid, adrenal cortex, and gonads
Then those glands make hormones using a negative feed back system that regulate the secretion of the appropriate hypothalamic hormone
what hormones does the endocrine system secrete?
Growth Hormone (GH)
Prolactin
Melanocyte stimulating hormone (MSH)
Thyroid stimulating hormone (TSH)
Andrenocorticotropic hormone (ACTH)
Follicle stimulating hormone (FSH)
Luteinizing Hormone (LH)