Outcome 4 Endocrine System Flashcards
Endocrine glands secrete _____ into the _____.
Endocrine glands secrete CHEMICALS (HORMONES) into the BLOOD
What do hormones do?
Perform general functions of communication and control but a SLOWER, LONGER-LASTING type of control than that provided by nerve impulses
Cells acted on by hormones are called ____ found within ____
Cells acted on by hormones are called TARGET CELLS found within TARGET ORGANS
Hormone secretion is controlled by _____
Homeostatic feedback
Negative feedback
Mechanisms or loops that reverse the direction of a change in a physiological system back towards a normal value. Allows the brain and body to have control over the secretion rates of hormones.
Ex: an increase in blood glucose triggers secretion of insulin. Because insulin promotes glucose uptake by the cells, the blood glucose level is restored it’s lower, normal level
Positive feedback
(Uncommon) mechanisms that amplify the physiological changes
Major hormones in the anterior pituitary
TSH- thyroid stimulating hormone
GH- growth hormone
ACTH- adrenocorticotropic hormone (stimulates the adrenal glands)
Major hormone of the posterior pituitary
ADH-antidiuretic hormone (stops you from producing urine so you pee less. It causes the kidney to conserve water)
Homeostasis
RELATIVE CONSTANCY OF INTERNAL ENVIRONMENT. The temp, salt content, acid level (PH), fluid volume and pressure, oxygen concentration, and over vital conditions must remain within acceptable limits
Endocrine glands
DUCTLESS GLANDS made up of cells that produce and release chemicals known as hormones into the INTERCELLULAR SPACES of surrounding tissues. The hormones are quickly picked up by the blood stream and distributed to target organs and cells
Exocrine glands
Collections of glandular tissue within an organ that produce and release NON-HORMONAL substances INTO DUCTS that empty onto a surface or into a cavity. EX sweat glands, salivary glands
Target cell
Each hormone molecule may bind to a cell that has specific receptors for that hormone, triggering a reaction in the cell
Electrolytes
Substances such as salts that dissolve or break apart in water solution to form electrically charged atoms (or groups of atoms) called ions
Electrolyte balance
Homeostasis or relative constancy of normal electrolyte levels in the body fluids
The ability to maintain the balance of body functions is related to ____
AGE! During childhood, homeostatic functions gradually become more and more efficient and effective. They operate with max efficiency and effectiveness during young adulthood. During late adulthood and old age they gradually become less and less efficient and effective
Pineal gland
- attached to the roof of the 3rd ventricle in the center of the brain (part of the diencephalon)
- contains calcium salts (brain sand) that can be seen on radiographic images especially CT
- pine cone shaped
- secretes the hormone melatonin -> helps set the body’s biological clock, by regulating sleep/wake patterns
- uses info regarding changing light levels to adjust its levels of melatonin
- melatonin levels INCREASE at night and DECREASE during the day
- easily located in a child but becomes fibrous and encrusted with calcium deposits as a person ages
- SAD -> seasonal affective disorder
Pituitary gland
- attached inferiorly to the hypothalamus by a stem-like structure
- located in the sella tursica
- encased in dura mater, and surrounded by the circle of Willis
- size and shape of a pea
- made up of an anterior and posterior portion
Posterior pituitary
- cellular structure similar to nervous tissue
- does not manufacture any hormones
- it STORES two hormones made by the Hypothalamus
- only one is pertinent in radiography ADH-> anti diuretic hormone
ADH- antidiuretic hormone
- Stops you from producing urine so you “pee” less. It causes the kidneys to conserve water
- stored in the posterior pituitary
- made by hypothalamus
Thymus
- located in mediastinum
- composed largely of lymphocytes
- plays a critical part in the body’s defences against infections -> vital immunity mechanism
Anterior pituitary
- cellular structure of a true endocrine gland
- manufactures 6 hormones only 3 are pertinent to radiography
- TSH -> thyroid stimulating hormone
- GH -> growth hormone
- ACTH -> adrenocorticotropic hormone (stimulates the adrenal glands)
Hyperpituitarism
- can cause over production of hormones
- BEFORE the fusion of growth plates will cause GIANTISM
- AFTER the fusion of growth plates will cause ACROMEGALY
Hypo-pituitarism is usually due to a _____ or _____
- Pituitary tumour or pituitary ischemia
- diagnosed with CT, MRI or Angio
- treated with hormone replacement
Hypopituitarism can cause ____
Achondroplasia