Animal Hormones Flashcards
Why do only specific target cells respond to a hormone?
Because only target cells have receptors for binding with that particular hormone.
Describe the functions of the nervous and the endocrine system:
-Nervous system: coordintes rapid, precise responses and mediate the body interaction with the external environment. -Endocrine system: controls processes that require duration rather than speed, especially to maintain homeostasis.
What is a hormone?
A chemical mediator that is secreted by endocrine cells into the blood, where it is then transported to target cells.
What are the four different types of extracellular communication:
1) Paracrines 2) Neurotransmitter 3) Hormones. 4) Neurohormones.
Describe paracrines:
Local chemical messengers whose effect is exerted only on neighbouring cells in the immediate sorroundings of the receptors.
Describe neurotransmitter
Released by neurons and are short distances chemical messenger.
Describe neurohormones:
Hormones released into the blood by neurosecretory neurons.
What are the 6 different functions of hormones:
1) Regulating metabolism, water and electrolyte balance. 2) Inducing adaptive changes to help the body cope with stressful situations. 3) Promoting smooth, sequential growth in development. 4) Controlling sexual differentiation and development.
What are thee factors that influce the plasma concentrations of hormones:
1) The hormone rate of secretion into the blood. 2) The rate of metabolic activation or conversion. 3) For lipophilic hormones the extenct of binding to the plasma membrane. 4) Its rate of removal from the blod by metabolic inactivation and excretion in the urine.
What are the 3 means of control of hormone secretion:
1) Negative-feedback control. 2) Neuroendocrine reflexes 3) Diurnal (circadian) Rhythms.
Describe negative-feedback control:
Maintain the plasma concentration of hormone at a given level.
Describe neuroendocrine reflexes:
Include neural as well as endocrine components and it produce a sudden increase in hormone secretion in resposne to specific stimulus.
Describe diurnal (circadian) rhythms:
The secretion rates of many hormones fluctuate up and down as a function of time.
What is endocrinology:
The study of homeostatic chemical adjustment and other activites accomplished by hormones.
What are the two main kind of hormones based on their chemical classificatio?
1) Hydrophilic 2) Lipophilic