Intro to Endocrine system 1 Flashcards
What are glands?
They are epithelial tissue derivatives specialised for secreting.
What is epithelial tissue?
It is a functional grouping of cells specialised in the exchange of material between the cell and it’s environment, lines and covers various body surfaces and cavities and forms secretory glands.
What is secretion?
It is the release from a cell in response to appropriate stimulation of specific products that have been produced by the cell.
What is communication critical for in cells?
Communication is critical for cell survival and function
What are the 2 major communication systems?
Nervous system and endocrine system
What are the 4 types of chemical messengers?
Autocrine/paracrine, neurotransmitter, neurohormones and hormones
What are autocrine and paracrine chemical messengers?
They are local chemical messengers.
They exert effect on neighbouring cells - paracrine
or on the same cell - autocrine
What are neurotransmitters?
They are short range chemical messengers.
They diffuse across synapses (narrow spaces) to act on adjoining target cells such as other neurons, a muscle or a gland
What are neurohormones?
They are hormones released into blood by neurosecretory neurons.
They are distributed through the blood to distant target cells.
What are hormones?
They are long range hormones.
They are secreted into the blood by endocrine glands in response to appropriate signal and they act on distant target cells.
Where does autocrine act?
Autocrine can act on itself
Where does paracrine act?
Paracrine can act on another cell that is close by
Where are neurohormones released by and into and what do they act similar to?
Neurohormones are released from synaptic vesicles by neurons and they are released into the blood where they act in a similar way to hormones.
What are hormones? 3 points
They are messengers of endocrine system.
They’re released from endocrine glands into the blood where they are transported.
The target cell expresses specific receptors .
Structure and chemical messenger of nervous system:
Wired system of neurons
Neurotransmitter
What is the target site for the nervous system and the distance of action?
Very close and it acts across the synaptic cleft
Major function of the nervous system:
Fast precise responses
How long is the nervous system response and duration of action?
Milliseconds
What is the structure and chemical messenger of endocrine system?
Endocrine system is a wireless system of glands and hormones are the chemical messenger
What is the target site and the distance of action of the endocrine system?
Far away and it is carried by the blood
What is the speed of response and duration of action of the endocrine system?
Minutes to hours for response
Minutes to days for duration of action
What is the major function of the endocrine system?
For long duration responses
What are the 2 main differences between hormones and neurotransmitters?
- Neural messages can only travel along existing nerve tracts; hormonal messages can travel in the circulatory system; thus any cell receiving blood is potentially able to receive a message.
- Neural messages are digital, all-or-none events that have rapid onset and offset; neural signals can take place in milliseconds; plus, electrical signal can travel along myelinated axons at speeds up to 100 meters per sec
WhereasnHormonal messages are analog, graded events that can take seconds, minutes or hours to occur.
How does a hormone exert its influence?
Only cells with receptors for that hormone can be influenced and they are called target cells
The interaction of a hormone with its receptor leads to a genomic response whereby the hormone activates genes that regulate protein synthesis (e.g., up-regulation: synthesis of a receptor for that hormone).
What are the 4 types of hormones?
Peptide, catecholamine, thyroid and steroids
Do hormones change the function of a cell?
Hormones rarely change the function of a cell, rather they alter the rate of normal cellular function, thus hormones affect cell morphology and size. Although they can affect behaviour, behaviour can also influence hormonal levels and effects.