2. Endocrine System Flashcards
endocrine glands release hormones into
blood vessels
hormones travel
through blood to target cells
Paracrine secretions
- act locally
- affect only neighboring cells
Autocrine secretions affect
only the secreting cell
define hormones
Chemical messengers secreted by endocrine glands that regulate functions of other cells
target cells
hormones are able to affect only particular cells called
Hydrophilic hormones
cannot readily cross plasma membrane so generally interact with receptors found embedded in target cell’s plasma membrane
Hydrophobic hormones
are able to cross through plasma membrane so generally interact with receptors found in cytosol or nucleus
secretion can be initiated or inhibited by several different stimuli
- Hormonal stimuli
- Humoral stimuli
- ## Neural stimuli
Hormonal stimuli
– some endocrine cells increase or decrease their secretion in response to secretion of other hormones
Humoral stimuli
– many endocrine cells respond to concentration of a certain ion or molecule in blood or extracellular fluid
Neural stimuli
– some endocrine cells respond to signals from nervous system
___________ help regulate hormones
feedback loops
feedback loops that regulate hormone secretion occur in following sequence…
- stimulus
- receptor
- control center
- effector/response
- homeostatic range
Stimulus
– a regulated physiological variable deviates from its normal range
Receptor
– receptors on target cells Receptor – receptors on target cells detect deviation of variable
Control center
- stimulated control center (often endocrine cell) increases or decreases its secretion of a particular hormone
Effector/response
– hormone triggers a response in its target cells that moves conditions toward normal range
Homeostatic range
– As variable returns to its normal range, feedback to control center decreases response
Steroid or Steroid-Like Hormones include
- sex hormones
- adrenal cortex hormones
Non-steroid Hormones
include
- amines
- proteins
- peptides
- glycoproteins
what are the major endocrine glands
- hypothalamus
- pituitary gland
- pineal gland
- parathyroid gland
- thyroid gland
thymus - adrenal gland
kidney - Panceas
- ovaries
- testies
The hypothalamus (4)
- Important regulatory center in the Nervous and Endocrine Systems
- Has cells that produce 9 different hormones
- Receives input from higher brain centers, thalamus, reticular formation, sensory signals from internal organs
- Regulates body temperature, rage, fear, thirst, hunger, sexual behavior etc.
Hypothalamus controls the secretion of hormones from the
pituitary gland
Pituitary gland controls the secretion of
hormones from other pituitary glands
Hypothalamus integrates functions of
Nervous and Endocrine systems
