lecture 1 general functions of endocrine system Flashcards
describe the major functions of the endocrine system
Major functions = communication and homeostasis
- To regulate growth and development, metabolism, reproduction, moos, responses to stress, maintaining internal balance (homeostasis), producing and releasing hormones into the bloodstream that target specific organs and tissues throughout the body
pineal gland
- Is in the brain to help regulate sleep and wake cycles. Specifically hangs from the roof of the third ventricle in the diencephalon.
- Produces melatonin which is what helps to further regulate the sleep and wake cycle
hypothalamus
- The hypothalamus if a structure deep within the brain which is the main link between the endocrine system and nervous system.
- It controls the release of hormones from other glands, such as the pituitary gland
pituitary gland
- Is a small pea sized gland that is located at the base of the brain directly below the hypothalamus.
- It secretes various hormones that influence other glands including the growth hormone, FSH, TSH, and LH
anterior pituitary gland
Is the front lobe of the pituitary gland and is crucial in regulating various bodily functions. Also produces growth hormone, TSH, FSH, and LH
posterior pituitary gland
- Is the back lobe of the pituitary gland and is made up of neural tissues to store and release hormones like oxytocin and vasopressin.
- Helps regulate things like childbirth, water balance, and sexual activity.
thyroid gland
In the neck, in the front of the throat. Produces hormones that regulate metabolism, heart rate, body temp, and more. Also helps to control growth and energy expenditure
parathyroid gland
- Are four pea sized glands in the neck that work together to produce the parathyroid hormone.
- Works to produce PTH which regulates calcium, phosphorous, and magnesium levels in the blood and bones.
thymus
- By the heart, or in the chest almost between the lungs.
- Produces T lymphocytes, and the hormone thymosin which helps develop T cells
adrenal gland
- is a pair of small triangular shaped glands that are located on the top of each kidney
- Helps to develop sex characteristics, and also production of hormones that help balance water and salt in the body
pancreas
- Is an elongated glandular organ that is in the abdomen behind the stomach.
- Produces digestive enzymes and hormones (insulin and glucagon which help regulate and control blood sugar levels). Helps to break down proteins, carbs, and fats.
gonads
these are the reproductive organs that produce sex cells and hormones
hormone
a long-distance chemical signals that travel in blood or lymph throughout the body
endocrine gland
also called ductless glands and produce hormones while lacking ducts. They release hormones into the surrounding tissue fluid. Typically have a rich vascular and lymphatic drainage that receives their hormones
exocrine gland
produce non hormonal substances, such as sweat and saliva, and have ducts that carry these substances to a membrane surface.
endocrine tissue (organ)
a group of glands that produce hormones that regulate many body functions
target cell
when a hormone influences the activity of only those tissue cells that have the receptors for it
- A specific cell that has receptors for a particular hormone, allows it to respond to that hormone’s signal when it binds to the receptor.
paracrine
A can talk to B if it is near, releasing targets near the molecule. Short-distance chemical signals that act locally but affect cell types other than those secreting them.
- self to close cells
autocrine
A talking to A, short distance on itself. Short-distance chemical signals that exert their efforts on the same cells that secrete them
To itself
endocrine
glands that have ducts through which their secretions are carried to a particular site.
- are long distance
humoral
- when an organ is serving things like blood
- changing and watching the blood levels of ions?, just from one gland
neural
- when the CNS senses the problem but needs to touch the endocrine glands to release another hormone
- derives from preganglionic sympathetic
- would be like from the vertebrae in the CNS to a gland
- derives from preganglionic sympathetic
hormonal
- can tell other glands to simply release even more hormones
- on other hormones
- is going from one gland out to many others in the body/endocrine system
- on other hormones
Describe a simple endocrine pathway in which the response is the negative feedback signal (e.g., parathyroid hormone, insulin).
Parathyroid hormone (PTH) pathway – these glands detect the decrease in blood calcium levels and then stimulate the release of the parathyroid hormone into the bloodstream.
- This stimulates the release of calcium from bones by activating osteoclasts and increases calcium absorption in the kidneys so that less calcium is being excreted from the urine.
- This is negative feedback because as the blood calcium levels start to rise which in turn inhibits further secretion of PTH.
peptides and proteins
- a protein coding gene is transcribed RNA polymerase in the nucleus and translated in the cytoplasm by a ribosome
- the peptide or protein is shipped outside of the cell
- water soluble or hydrophilic - things cannot simply travel in and out of a cell they have to go through a process to get in or leave the cell
G protein -> effector -> second messenger -> (amplification) - change in that cell
amines (amino acid derived hormones)
- derived tyrosine
- catecholamines (epinephrine, norepinephrine, and dopamine)
- thyroid hormones - derived from tryptophan
- serotonin and melatonin
steroids
- all are derived from cholesterol
- from the adrenal cortex, gonads, corpus luteum, and placenta
- cortisol, aldosterone, estradiol and estriol, progesterone and testosterone, etc.
how to identify the steroid hormone
- have four fused carbon rings (hexagons), derived from cholesterol, lipid soluble (hydrophobic), made in the SER and mitochondria
how to identify the amines
one full carbon ring, and one house shaped piece, are biochemically modified amino acids
how to identify peptides and proteins
looks like a snaking line and complex structure (insulin). will have a prepro and pro stage before being the actual peptide or protein
Describe how the endocrine system functions,
The endocrine system is responsible for many functions including regulation of physiological processes, metabolism, growth, development, mood, reproductive functions, release of hormones, and they all act as chemical signals in the body.
the anatomical pathways by which the signals reach their targets of the endocrine system
The steps of the pathway from hormone production to the target organ
- The hormones are secreted by specific glands
- Then after secretion the hormones will enter the bloodstream which in turn works to transport them through the body
- Last the hormones will bind to their specific receptors either on the surface or on the inside of the cell.
what determines the target of the pathway,
The target of the hormone is determined by what the presence of the specific receptors on the target cell are. This means that only the cells with the receptor type that matches the hormone will respond.
Compare endocrine to neural communication
- Endocrine – uses hormones, which travel through the blood stream, have slower response times which are longer lasting (minutes to days), and has the signal intensity encoded by the hormone concentration, exposure time, and receptor sensitivity
- Nervous – uses neurotransmitters (chemical), they transmit electrical impulses along axons to act on nearby cells, has a much faster response time (milliseconds to seconds), the response time is typically in short durations, and the signal intensity is coded by the frequency and pattern of the action potentials
what determines the speed of the target response(s), the duration of the response, and how signal intensity is coded.
- While endocrine responses are slower than neural, the responses speed is based on not only where it is going in the body (how far it has to travel in the bloodstream).
- The duration of the response, however, can depend on what the hormone is, what it is doing, and where it is going. These responses can last for days.
- Signal intensity is coded based on the hormone concentration, the duration of the exposure, and the receptor sensitivity.
Compare and contrast how steroid and peptide hormones are produced
Steroid – synthesized from cholesterol and undergo enzymatic modifications to for the specific steroid hormone that is needed. The synthesis is primarily in the SER and mitochondria
Peptide – synthesized as a large precursor proteins primarily in the RER. Tend to also show up in the golgi apparatus
compare and contrast how the steroid and peptide hormones are released from the endocrine cell from the cell
Steroid – since they are lipid soluble, they diffuse directly through the plasma membrane of the cell. Have there receptors on the inside of the cell. Once they are synthesized, they go directly through and quickly into the bloodstream.
Peptide – they are stored in the secretory vesicles of the cell and released through exocytosis. Released into the extracellular space
Are not lipid soluble and have their receptors outside so they cannot simply just go through the plasma membrane. They have to actually do the work
compare and contrast how the steroid and peptide hormones are stored in the endocrine cell
Steroid – they are lipid soluble and are synthesized on demand as they are needed in the body. They are immediately released into the bloodstream when needed.
Peptide – stored in the secretory vesicles in the cell and are ready to be released when triggered by a signal that is typically from a stimulus being released.
compare and contrast how the steroid and peptide hormones are transported in the blood from the cell
Steroid – they do not dissolve easily in the bloodstream; therefore, they are typically bonded with carrier proteins (sex hormone binding globulin and corticosteroid binding hormone) to further decrease their ability to dissolve while being transported in blood
Peptide – since these are lipid soluble and dissolve easily, they can easily go through the bloodstream and dissolve freely. Move freely due to their solubility
