Chapter 20: Endocrine System Flashcards
Define endocrine system.
A system involving glands and hormones (that are released into the blood stream) to help maintain homeostasis in the body.
Define endocrinology.
The study of the structural components of the endocrine system, the hormones they produce, and the effects of those hormones on target organs.
List and describe the functions of the endocrine system. (3)
- Work with the nervous system to maintain homeostasis.
- Regulate certain body functions.
- Use hormones rather than nerve impulses
Discuss the characteristics of endocrine glands and list some examples.
- Exocrine Glands
- DUCTS: secretions released into ducts opening onto an epithelial surface - Endocrine glands
- DUCTLESS: organs that secrete their molecules directly into the bloodstream
- Located in highly vascularized areas to ensure that their products enter the blood stream immediately
Major Endocrine Glands: Pituitary Gland Pineal Gland Thyroid Gland Parathyroid Glands Adrenal Glands
Identify similarities and differences between the endocrine system and the nervous system. Also, discuss how they interact.
Endocrine System (ES) Vs Nervous System (NS)
Communication:
- ES: secretes hormones into the blood and they are carried throughout the body to their target organs
- NS: uses nerve impulses that signal neurotransmitter released from a neuron into a synaptic cleft
Target of stimulation:
- ES: any cell in the body with a receptor for the hormone
- NS: other neurons, muscle cells, and gland cells
Response time:
- ES: Slow rxn time; seconds/min/hrs
- NS: Fast run time; Milliseconds/Seconds
Effect of Stimulation:
- ES: Causes metabolic changes in target cells
- NS: Causes stimulation/inhibition of another neuron; contraction/relaxation in muscles
Range of Effect
- ES: Widespread bodily effects
- NS: Localized, specific effects on the body
Duration of Response
- ES: Long-lasting; min/days/weeks; may continue after stimulus is removed
- NS: Short-term; milliseconds; terminates with stimulus is removed
Discuss what hormones are and how they effect target organs and cells.
- Molecules that have an effect on specific organs
- Only cells/tissue/organs with specific receptors for the hormone respond to that hormone
List and discuss the 2 different types of feedback loops.
- Negative Feedback Loop:
- Stimulus starts a process and eventually either the hormone that is secreted or a product of its effects causes the process to slow down to turn off
- ie. Regulation of blood glucose in the body - Positive Feedback Loop:
- Stimulus occurs and accelerates a process, either by ensuring that the pathway continues to run or speeds up its activities
- ie. breast feeding
Explain the relationship between the hypothalamus and the endocrine system
Hypothalamus is the master control center of the endocrine system and oversees most endocrine activity in 3 main ways:
- Cells in hypothalamus secrete hormones to act on pituitary gland causing it to secrete regulatory hormones into the blood stream
- Hypothalamus produces 2 hormones that are transported to and stored in pituitary
- Direct stimulation of adrenal gland - sympathetic response
Identify the location and main secretion and major effects of the:
Pituitary Gland
- Inferior to hypothalamus, in sellae turcica
- Releases growth hormone (GH), hormones that act on the gonads (FSH, LH), a hormone that acts on the thyroid (TSH), one that acts on the mammary glands to stimulate milk production, a hormone that acts on the adrenal gland
Identify the location and main secretion and major effects of the:
Thyroid Gland
- Inferior to the thyroid cartilage of the larynx, butterfly shape/2 lobes
- stimulated follicular cells of the thyroid gland release a hormone that stimulates target cells to respond to a stimulus
Identify the location and main secretion and major effects of the:
Parathyroid Glands
- on posterior surface of thyroid gland
- contain chief cells and oxyphil cells
- contain a hormone that stimulates osteoclasts to reabsorb bone and release Ca
- promotes Ca absorption in small intestines and prevents loss of Ca when making urine
Identify the location and main secretion and major effects of the:
Adrenal Glands
- superior surface of the kidneys like hats
- ## secrete different types of hormones; corticosteriods that regulate salt, sugar, and sex
Identify the location and main secretion and major effects of the:
Pancreas
- posterior to stomach, between duodenum and spleen
- produces pancreatic juice that aides in digestion
- secretes glucagon when blood sugar is low
- secretes insulin when blood sugar is high
- pancreatic hormones provide orderly uptake and processing of nutrients
Identify the location and main secretion and major effects of the:
Pineal gland
- posterior region of the epithalamus
- secretes melatonin to help regulate sleep/wake cycles
- decreases in size as we age
Identify the location and main secretion and major effects of the:
Thymus
- superior to the heart, posterior to the sternum
- functions associated with the lymphatic system to regulate and maintain body immunity
- secrete hormones that stimulate production and maturation of T-lymphocytes
