Endocrine Flashcards
Define Endocrine System
A scattered collection of ductless glands and individual cells that secrete chemical messengers called hormones
Define Hormones
Chemicals that alter the metabolism of specific cells called their target cells
Define target cells
Peripheral cells that respond to a particular hormone because they have specific receptors for those hormones
Define Hormone Receptors
A protein in the plasma membrane, or within the cytoplasm or nucleus of the target cell. The hormone needs to to it’s specific receptor to trigger a response from the target cell
List the pure endocrine glands
Pineal gland, pituitary gland, hypothalamus, parathyroid gland, thyroid gland, adrenal glands, pancreas
List organs with secondary endocrine function
Heart, thymus, adipose tissue, digestive tract, kidneys, gonads (testes in men; ovaries in women)
Along with the endocrine, what is the other regulatory system in the body?
The nervous system
What are the similarities and differences between the nervous and endocrine systems?
They both use chemical substances as messages. Nervous systems chemical messengers are called neurotransmitters. Endocrine systems chemical messengers are called hormones. They both need receptors on target cells/organs.
The nervous systems’ target cells/organs are across a small synapse, while endocrine’s can be anywhere in the body. Neurotransmitters often act within milliseconds with the effects only lasting a very short time (milliseconds). Hormones may take minutes to days to act and their effects may last minutes, hours, days, months…very long periods of time.
What is the primary difference between exocrine and endocrine glands?
Exocrine glands use duct that catch the secretions, and endocrine is ductless.
An endocrine gland releases a hormone into the
Surrounding extracellular fluid (a lot of times into the blood stream)
1st step to the mechanism of hormone action
- Endocrine cells receive and respond to stimuli (changes) which led to the release of the chemical messengers.
2nd step of the mechanism of hormone action
- Hormones are released into the extracellular fluid and may act on local cells or the hormones will diffuse into the blood and travel around the body
3rd step in the mechanism of hormone action
- The hormones will only act on their target cells, cells which have the matching receptors for the hormones
4th step in the mechanism of hormone action
- This results in a change in activity in the target cells
These hormones can be made of a single, modified amino acid or a polymer of amino acids and are large molecules
Hormones made of amino acids
What class of hormones cannot enter their target cells? Where are their receptors located?
Hormones made of amino-acids. Their receptors are located on the plasma membrane.
What class of hormone is able to enter their target cells? And where are the receptors located?
Hormones made of steroids. Their receptors are located inside the target cells.
Hormones made from steroids are…
Derived from cholesterol and are thus types of lipids
Location of the hypothalamus
In the diencephalon, just inferior to the thalamus
Structure of the hypothalamus
Composed of collections of cell bodies of neurons
What is the name of the structure that connects the pituitary gland to the hypothalamus ?
Infundibulum
The pituitary gland also known as the ….., is composed of 2 lobes.
Hypophysis
The anterior lobe is composed of ……. cells.
Endocrine
What is the vascular structure that delivers hormones from the hypothalamus to the anterior pituitary lobe.
Capillaries
Releasing and inhibiting hormones are released from the ….. and travel to the anterior pituitary.
Hypothalamus
Releasing hormones, also known as ….. hormones, cause the release of specific hormones from the anterior pituitary.
Tropic
The posterior pituitary is composed of ….. of neurons located in the hypothalamus
Axons
What is the name of the bundle of axons if these hypothalamic neurons that travel through the infundibulum?
Hypothalamic hypophyseal tract
Location of the thyroid gland
Anterior neck; inferior to the “Adam’s Appel” of the larynx
Thyroid gland macroscopic anatomy
Two lobes connected by a more narrow isthmus
What is the follicle in the thyroid gland?
A spherical structure lined by follicular cells surrounding a central area where a viscous fluid called colloid is located
What is the colloid in the thyroid gland?
A viscous fluid that stores the thyroid hormone precursors
Where are parafollicular cells (c-cells) located? What do they release ?
Located outside of the follicles. Release the calcitonin hormone.
What are the two thyroid hormones?
Thyroid hormone T3 (triiodothyronine)
Thyroid hormone T4 (thyroxine)
What is the primary function of the thyroid hormones?
Binding of hormones increases cellular metabolism
Calcitonin’s stimulus for release
Blood calcium levels are high
Calcitonin’s target cell
Bone cells and osteoblasts
Calcitonin’s effect of hormone
Increase new bone matrix formation
Parathyroid gland location
Attached to the posterior surface of the thyroid gland
Parathyroid gland gross anatomy
4 small spherical glands
Hormone produced in the parathyroid gland
Parathyroid hormone (PTH)
Parathyroid hormone stimulus for release
Blood calcium levels are low
Parathyroid hormone target cells and effect
Kidney - increase calcium reabsorption
Bones - increase osteoclasts activity
Intestines - increase calcium absorption
Parathyroid hormone is the most common hormonal regulator for ….
Increasing blood calcium
Adrenal glands location
Superior to each kidney
Adrenal gland’s macroscopic anatomy
Pyramidal shape with cortex-outer region; medulla-center of gland
The cortex of the adrenal gland is composed of …. regions
3
The cortex produces hormones that are collectively called the……
Corticosteroids
List the 3 hormones produced by the adrenal cortex
Mineralocorticoids
Glucocorticoids
Gondocorticoids
What is the medulla composed of?
Modified , sympathetic postganglionic neurons
What two hormones are produced by the medulla?
Epinephrine and Norepinephrine
Location of the pancreas
LUQ; in the “J” shaped loop between the stomach and the proximal part of the small intestine
Describe the pancreas head
Wider, more medically located; surrounded by part of the small intestine called the duodenum
Describe the pancreas body
The middle mass of the pancreas
Describe the pancreas tail
More narrow, laterally located; abuts the spleen
The endocrine structure in the pancreas are called the
Pancreatic islets
Cells produced by the pancreas
Alpha cells and Beta cells
Hormones secreted by the pancreas
Glucagon and Insulin
Glucagon stimulus for release
Low blood glucose levels
Insulin stimulus for release
High blood glucose levels
Glucagon target cells/effect
Stimulate the breakdown of glycogen stored in the liver and skeletal muscles to free glucose and increase blood glucose levels
Insulin target cells/effect
Helping glucose enter many cells of the body; leading to a decrease in blood glucose levels
The two pancreatic hormones are vital for the homeostatic regulation of …… levels in the blood
Glucose
Pancreatic hormones control the blood glucose level by the process of …..
Negative feedback
What is the most common disease associated with an endocrine disorder?
Diabetes mellitus
Type 1 and Type 2 Diabetes cause and treatment
Cause - high blood glucose levels
Treatment - Diabetes medication, Blood sugar monitoring, Insulin pills, Insulin injections, or Insulin patch
What are the male gonads?
Testes
Primary hormone produced by the testes
Testosterone
Function of testosterone
Controls production of sperm and the development of secondary sex characteristics in the male
What are the female gonads?
Ovaries
Primary hormone produced by ovaries
Estrogen and progesterone
Functions of the ovarian hormones
Estrogen controls follicle maturation and the development of female secondary sex characteristics. Progesterone prepares the uterus for the implantation of a fertilized egg.
