Endocrine System Flashcards
What major long-term processes are stimulated by hormones?
- Growth and development
- Metabolism
- Reproduction
- Energy balance
- Fluid and electrolyte balance
- Fight or flight response
What are 3 of the main electrolytes and what is their function?
- Potassium = nerve impulse transmission
- Sodium = BP
- Calcium = bone growth
How do exocrine glands work?
They release products at the body’s surface or into body cavities through ducts
- Examples: sweat/oil glands, liver, pancreas, salivary, prostate
How do endocrine glands work?
They release products directly into the bloodstream
Do not have ducts
- Examples: pineal, pituitary, thyroid, hypothalamus, adrenal
What are the 2 main types of exocrine glands?
- Simple duct structure
2. Compound duct structure (duct branches)
What are the 2 structures of simple duct exocrine glands? Give 2 examples for each
- Tubular secretory structure
- Simple tubular (intestinal glands)
- Simple branched tubular (gastric glands) - Alveolar secretory structure
- Simple alveolar (paraurethral gland)
- Simple branched alveolar (sebaceous glands)
What are the 2 structures of compound duct exocrine glands? Give examples for each
- Tubular secretory structure
- Compound tubular (duodenal glands) - Alveolar secretory structure
- Compound alveolar (mammary glands)
- Compound tubuloalveolar (salivary glands)
Name 2 parts of the body that have secondary endocrine function
- Kidneys
2. Bone
Describe the pituitary gland
- Located at the base of the brain
- 2 parts: anterior and posterior
- Hypothalamus controls the secretions of the pituitary gland
Describe the posterior pituitary gland
- Formed of nerve cells surrounded by glial cells
- Hormones synthesised in the nerve cell bodies and stored in vesicles in the axon terminals
- Nerve impulses then trigger exocytosis of the vesicles to release the hormones
What does the hypothalamus regulate?
- Temperature
- Thirst and hunger
- Sex drive
- Urine production
Describe how the hypothalamus works
- Autonomic NS centre
- Controls the pituitary gland using neuro-secretory cells
- Produces relaxing hormones that control the anterior pituitary (AP) gland secretions
- Blood flows through the hypothalamus and then the AP gland, releasing and inhibiting hormones
Where is the thyroid gland located?
At the front of the larynx and trachea at the level of the 5th, 6th and 7th cervical vertebrae
Describe the thyroid gland
- Surrounded by a fibrous capsule
- Blood is supplied via the thyroid arteries
- There are 4 parathyroid glands
- Iodine is essential for the formation of thyroid hormones
What is Calcitonin and how does it work?
- Hormone produced in the thyroid gland
- Lowers calcium levels by acting on bone cells to promote calcium storage and kidney tubules to inhibit calcium reabsorption
- Works with the parathyroid hormone to maintain calcium homeostasis
How does the parathyroid hormone work?
Has the opposite effect of Calcitonin; stimulates bone destruction to increase calcium levels
Describe the adrenal glands
- Make hormones that help the body prepare for and deal with stress
- Consist of a cortex and a medulla
What does the adrenal cortex produce?
Corticosteroids which help maintain homeostasis
What are the 3 groups of corticosteroids?
- Mineralocorticoids
- Glucocorticoids
- Sex hormones
What does the adrenal medulla produce?
Epinephrine and Norepinephrine
What is another name for epinephrine and what effect does it have?
- Adrenaline
- Reduces vasodilation
- Increases vascular permeability
What is another name for norepinephrine and what effect does it have?
- Noradrenaline
- Vasoconstrictor
- Inotropic stimulator of the heart
- Dilator of coronary arteries
What is unique about the pancreas and what are the 3 types of cells that it is made up of?
It has both exocrine and endocrine function
- alpha cells
- beta cells
- delta cells
What are hormones?
- Chemical messengers produced in the body
- Generally pass directly into the bloodstream
- Influence other cells and tissues
What is a tropic hormone?
A hormone that has other endocrine glands as its target
What are the 2 main types of hormones?
- Circulating hormone - diffuses into the blood to activate target cells far away
- Local hormone- affect target cells close to their release site
What are the 2 main types of local hormone?
- Autocrine - hormone-releasing cell is affected
2. Paracrine - hormone affects nearby cells only