Introduction to the endocrine system Flashcards
What is the simplest form of intercellular communication is for cell A to…
…release a chemical substance into the extracellular fluid. Some of the chemical will arrive at cell B and will influence the activity of that cell, hence the message will have been transmitted.
The major problems with the simplest form of intercellular communication is that…
… it is non-specific, as many other cells may also receive the chemical message and that a large amount of transmitter substance must be released in order to ensure that the desired cell receives the message.
What will happen is cell A and cell B are further apart?
The greater the distance between the cells are, the amount of transmitter substance that must be secreted increases, hence there are greater problems of NON-SPECIFICITY of action, that is, a greater number of cells receive the message that is only intended for cell B.
How is non specificity overcome?
By the development of outgrowths from cell A towards the target cell. The cell may then become further specialised by only releasing transmitter from one area of its surface. This specialisation is the beginning of a nerve cell.
What is a drawback of neuronal form of intercellular communication?
Each cell can only communicate directly with a limited number of other cells. The organism therefore requires a method by which a single cell can communicate with a large number of widely distributed cells.
What is the nervous system?
The nervous system responds to stimuli by sending electrical action potentials along neurons, which in turn transmit these action potentials to their target cells using neurotransmitters, the chemical messenger of the nervous system. This response to stimuli is near instantaneous.
The nervous system allows very
rapid, focussed, precise communication between INDIVIDUAL cells.
The endocrine system allows very
slow, sustained communication between GROUPS of cells.
The nervous and endocrine systems both work together to maintain __________
homeostasis.
The signal is ________ BETWEEN neurones and _____ within neurones.
chemical
electrical
Why does chemical transmission take longer than electrical transmission?
This process takes significantly longer, as hormones must first be synthesized, transported to their target cell, and enter or signal the cell. Then, the target cell must go through the process of transcription, translation, and protein synthesis before the intended action of the hormone is seen.
Define the endocrine system.
A system in which a group of secretory cells (a gland) secretes a potent chemical transmitter substance (hormone) into the blood. The transmitter is then carried by the blood to the target cells where a response is elicited. Endocrine glands are ductless glands and their hormone transmitters are always secreted into the blood.
What are two functions of the pineal gland?
It controls the onset of menstrual cycle and puberty.
It controls melatonin levels.
Name the endocrine glands from top (head) to bottom (toe)
Hypothalamus Pineal Pituitary Parathyroid Thyroid Thymus Adrenal Kidney Pancreas Ovary Testes
What is the function of thymus?
Increase cell proliferation
The pituitary gland is located where and is sometimes called what gland?
below the brain. encased in skull. It is sometimes called the ‘master gland’
Where are the thyroid and parathyroid glands situated? Expand on each gland.
Situated in the neck.
Thyroid responsible for metabolism and growth.
Parathyroid responsible for calcium homeostasis and phopshate homeostasis (maintenance and regulation)
Excess calcium can cause _________. This is caused by malfunction of the ________ gland.
kidney stones
parathyroid
Give examples of glands that are both endocrine and exocrine glands?
Pancreas
Liver - growth hormone into blood (endo)/ bile into small intestines (exocrine)
Why is pancreas both an exocrine and endocrine gland?
The pancreas secretes digestive enzymes directly into the GI tract (exocrine function). It also secretes the hormone insulin directly into the blood (endocrine function). Insulin regulates blood glucose concentration and glucose utilisation.
The pancreas has lots of ____ cells. State what the majority of the cells are and what each cell secretes.
islet
beta - insulin
alpha - glucagon
delta - somatostatin
Where do the adrenal glands lie? Expand on the divisions
above the kidneys
outer cortex involved in stress, sodium and glucose homeostasis
inner medulla involved in stress response
What are the gonads and what are they responsible for?
ovaries and testes.
secrete the female and male reproductive hormones respectively. These are responsible for the development of secondary sexual characteristics and reproduction.
Like drugs, hormones produce their effects by interaction with receptors which may be ________ or ________-_____. What are the major types of receptor involved?
intracellular
membrane bound
Steroid hormone receptors, G-protein coupled receptors and Tyrosine Kinase receptors
