Endocrine System Flashcards
(45 cards)
What is the endocrine system
The collection of glands and secretory tissues whose function is to regulate multiple organs in the body
What are the 2 functions of the endocrine system
- Respond to fluctuations within the internal environment to maintain homeostasis
- Meet growth and reproductive needs of organism
Why do animals have endocrine system instead of paracrine
Acts via hormones and blood stream because the target cells are too distant to be reached by diffusion
Autocrine signalling
cell releases the signal to which it itself responds to
How does the endocrine system work
Migrate substance into circulatory system which allow substances to travel throughout the body, and be released from the circulatory system to cells throughout the body
How do paracrine signals work
Diffuses into the interstitial fluid and elicits its response in the neighboring cells (gradient of signal, the further the fell is away from the source the less it will see)
Where are hormones produced
endocrine cells
What are endocrine cells
Ductless organs excrete outside the cell, into interstitial fluid where it then diffuses into the circulatory system
Why do endocrine glands have lots of capillaries
Dense network of capillaries in endocrine glands to quickly take up hormones and spread them throughout the body
How many endocrine glands do we have and what are they
9 overall, 8 per sex
- Pineal - Hypothalamus - Pituitary gland (master regulator) - Thyroid Gland - Parathyroid Gland - Adrenal Glands - Pancreas - Ovaries -Testes
What are hormones
Chemical signals that are secreted into the circulatory system and communicate regulatory messages throughout the body.
(Long-distance regulators in the body)
What do protozoans use as communication signals
Use secreted chemicals called pheromones (or gamones) for mating purposes
Why do protozoans need pheromones
communicate to undergo sexual reproduction
Protozoans
unicellular eukaryotes
metazoans
multicellular animals
What happened with the development of multicellularity
metazoans established short distance paracrine signalling
Limitations of paracrine signalling and the effect of this
limited to a distance of about 10 cells (limited to simple animals)
What version of endocrine system do phyla with lower physiological and anatomical complexity have
Neural systems but not an endocrine or circulatory system because they have lower physiological/anatomical complexity
Where does paracrine signalling occur in the neural system
At the end of axons, in the synapse
Where are chemical signals released in the neuron
By the synapse, at the end of the axon
Why not ONLY use the nervous system to communicate over long distances
Does not suffice due to dilution effect
2 advantages of endocrine system in addition to a neural system
A) blood vessels are designed to reach every cell in the body (because every cell in the body needs oxygen, nutrients, excretion)
B) Hormones are more suited for long-term effects (minutes to years) - whereas nerves work on more immediate responses
Why does the endocrine system require the circulatory system
Allow long-distance dispersal of chemical signals to alll the cells in the body
How did endocrine glands form
Hormone-producing cells accumulated together into glands