Endocrine System, Glands and Hormones Flashcards
(19 cards)
The Endocrine System
The endocrine system aids the body in synthesizing hormones and coordinating the activities of organ systems
This is important for the organism so it can respond to the changing external environment in a synchronized manner
Endocrine and Exocrine Glands
Endocrine glands synthesize hormones and secrete them into the bloodstream
Exocrine glands secrete substances through ducts or tubes onto a body surface or into a cavity
Most of the body’s glands are exocrine glands
Chemical Control Systems
The nervous and endocrine systems provide integration and control of the organs and tissues
The malfunction of one organ affects other organs; however, an animal can continue to function because of compensations made by the two control systems
The nervous system enables the body to adjust quickly to changes in the environment
The endocrine system is designed to maintain control over a longer duration
Hormones
Hormones are chemical messengers secreted into the blood by endocrine cells or specialized neurons
Processes that fall mostly under hormonal control include:
Growth and development
Metabolism
Regulation of internal environment (temperature, water balance, ions)
Reproduction
Effects of Hormones
Hormones act on their target cells in one of three basic ways:
Control the rates of enzymatic reactions
Control transport of molecules across cell membranes
Control gene expression and the synthesis of proteins
Effects on target cells can be very complex
Receptors
Each hormone has a specific receptor on the target cell
The specificity of a hormone depends as much on its receptors as on any property of the hormone itself
Steroid and Protein Hormones
Steroid –> made from cholesterol, soluble in fat, easily cross membranes
protien –> made of peptide chians of varying length, soluble in water, cannot easily cross membranes
Hormones and Receptors
Only cells that contain surface or internal receptors for the hormones respond to the hormones
Once bound to their receptors, hormones produce a response by turning cellular processes on or off by altering proteins that are functioning in or produced by the cell
Hormones are effective in very small concentrations because of the amplification that occurs in both the surface and internal receptor mechanisms
The response to a hormone differs among target organs and species
Hypothalamus
A portion of the brain that contains a number of small nuclei
Hormones produced: releasing and inhibiting hormones
Target tissue: anterior pituitary gland
Function: regulates the secretion of anterior pituitary hormones
Pituitary Gland
A small sac-like structure connected by a stalk to the
hypothalamus
(has an anterior lobe and a posterior lobe)
Anterior hormones + function
- prololactin (PRL) -mammary glands, stimultes breast development/milk production
- growth hormone (GH) -bone, soft tissue, stimultes growth of bones/soft tissue
- thyriod-stimulating hormone (TSH)-thyroid galnd, stimules secretion of thyroid hormones.
- adrenocorticotropic hormone (ACTH) -adrenal cortex, stimultes the secretion of cortiocosteriods.
- follicle-stimulating hormone (FSH) - ovaries/testes, regulates ovulation in females/secretion fo sex hormones in males
- lutenizing hormone (LH)-overies/testes, regulates ovulation in females/secretion of sex hormones in males
- melanocyte-stimulating hormone (MSH)-skin, promotes darkening of the skin
- endorphines-nervous system, inhibit perception of pain
Posterior pituitary gland + function
- antibiuretic hormone (ADH)-kidneys, increases water reabsorption
- oxytocin-uterus and mammary glands, promotes uterine contrations/stimulates milk release.
Thyroid Gland
A bow-tie shaped gland located at the front of the throat
- thyroxine(T4) - most cells, increases metabolic rate
- calcitonin - bone, owers the calcuim concentration in the blood
Parathyroid Gland
Four glands on the posterior aspect of the thyroid gland
- parathyriod hormone-bones kidneys and intestines, increase calcium concentration in the blood/activates vitamin D causing more calcium to be absorbed
Adrenal Glands, what hormones are produced and target tissue
Glands that are located on top of the kidneys
- (nor)epinephrine - most cells, prepares the body to respond to stress
- aldosterone-kidney tubules, aids in osmoregulation nad blood pressure
- cortisol-most cells, promotes gluconeogenesis/impairs protien synthesis
pineal gland
located in the brain of mammals, shapes line a pinecone
- melatonin-brain, synchronize biological clock with day’s length
gonads
male and female reproductive organs (testes and ovaries)
- follicle-stimulating hormone (FSH)-gonads, promotes spematogenesis and promotes oogenesis/synthesis of estrogen
- lutenizing hormone (LH) -gonads, synthesis of testosterone and ovulation/production of corpus luteum
interactions of glands
- the endocrine glands work together to maintain homeostasis
- each hormone has it’s own unique effects on target tissues
