Lecture 12 - Endocrine System Flashcards
What does the endocrine system do?
Works with the nervous system to control homeostasis
Function of Endocrine vs Nervous system
Endocrine
- > releases hormones into bloodstream from ductless glands and travel throughout body (longer lasting)
Nervous
- > releases neurotransmitters to excited/inhibit nerves, muscles, and gland cells (instant, brief )
Explain how hormone receptors effect target cells
- > endocrine cells release hormones into the blood stream
- > these hormones don’t affect all other cells, they only affect cells with certain receptors
- > target cells must have a specific hormone receptor for the cell do be affected by the hormone in question
Explain a negative feedback loop
- > the stimulus starts the process
- > the end result in to negate/ reverse the effects of the stimulus
- > i.e low blood sugar, insulin comes in to raise/ fix levels
Explain a positive feedback loop
- > does not produce a counteracting effect
- > stimulus accelerates the process until the stimulus is removed, then the process halts
- > childbirth, breastfeeding
List all major endocrine organs
What does the hypothalamus control (endocrine system)
- > controls and oversees most endocrine functions
- > interface between the nervous system and endocrine systems
- > master gland of the endocrine system
Where is hypothalamus and pituitary gland located
in the inferior region of the diencephalon, just superior to the pituitary
HOW does the hypothalamus control endocine activity
- Controls the release of six regulatory hormones from the ANTERIOR pituitary gland
- Secretes oxytocin (OT) and adtidieuretic hormone (ADH) from the POSTERIOR pituitary gland
- Controls the stimulation and secretion activities of the adrenal medulla
Physical characteristics of the pituitary gland
- > housed within the sella turnica of the sphenoid bone
- > connected to the hypothalamus by thin stalk called infundibulum
- > divided into anterior and posterior lobes
Thymus vs thalamus
Thymus - > imune system gland
Thyroid - > endocrine system gland
What makes up the adenohypophysis
*NOT HYPOTHESIS; ALSO KNOWN AS ANTERIOR PITUITARY*
- > Pars Distalis
- > Pars Intermedia
- > Pars Tuberalis
What are the six hormones of the anterior pituitary
- Growth Hormone (GH) - also called somatotropin
- Follicle stimulating hormone (FSH)
- Luteinizing hormone
- Prolactin (PRL)
- Adrenocorticotropin hormone (ACTH)
- Thyroid Stimulating hormone (TSH)
Infundibulum
the hollow stalk which connects the hypothalamus and the posterior pituitary gland
Explain the function of the human growth hormone
- > produced by somatotrophic cells
- > increases cell growth and cell division by increasing their uptake of amino acids and synthesis of protein
- > common targets cells are liver, skeletal muscles, cartilage and bone ( especially collagen)
Hyposecretion vs hypersecretion of human growth hormone
Hyposecretion - > Dwarfism
Hypersecretion - > Giantism
Explain the functions of the follicle stimulating hormone
*released by gonadotrophs*
- > initiates the formation of follicles within the ovary
- > stimulates follicle cells to secrete estrogen
- > stimulate sperm production in testes
Explain the function of luteinizing hormone
*produced by gonadotrophs*
In females…
- > triggers ovulation
- > secretion of estrogen and progesteron
In males…
- > stimulates secretion of testosterone
Explain the function of prolactin
*produced by lactotrophs*
- > prolactin causes milk production
- > function in males is unknown
Explain the function of adrenocorticotrophic hormone
*secreted by corticotrophs*
- > stimulates cells of the adrena cortex that produce glucocorticoids (helps the body resists stressors)
Explain the function of thyroid stimulating hormone
*secreted by thyrotrophs, which acts on the thyroid gland*
- > stimulates the production of T3 (3 iodine molecules) and T4 (4 iodine) thyroid hormones that regulate metabolism of most body tissues
Function of Neurohypophysis
*Posterior pituitary gland, which consists of axon terminals of hypothalamic neurons*
- > neurons release 2 neurotransmitters that enter capilaries
1. Antidiuretic hormone (ADH)
2. Oxytocin (OT)
Explain the functions of Antidiuretic hormone
*also known as vasopressin*
Functions (response to low blood pressure)
- > helps kindeys maintain water
- > decrease urine production
- > decrease sweating
- > increase BP
- > increase thirst
What happens when you lose too much sweat
- > changes the viscosity/density of your blood, which signals you to stop sweating/producing urine(kindeys) to preserve water
Explain the function of oxytocin
During Delivery:
- > hormone release enchances muscle contraction
After delivery:
- > suckling & hearing baby’s cry stimulates milk release
- > hormone causes muscle contraction and milk ejection
Physical characteristics of thyroid gland
- > largest gland entirely devoted to endocrine activities
- > located just inferior to they thyroid cartilage and anterior to the trachea
- > butterfly-shaped with right and left lobes connected by a midline isthmus
What makes up the thyroid gland
- > consists of follicular cells surrounding follicles filled with precursor substance (thyroglobulin)
- > active form of thyroglobulin is called thyroid hormone (T3, T4, bound to iodine)
Function of thyroid hormone
- > regulate oxygen use and metabolic rate
- > cellular metabolism of just about all cells
- > growth and development, particularily skeletal and nervous tissues
- > Regulate Ca and P metabolism, bone maintenance
Parathyroid glands
- > small glands (usually four) embeded on the posterior surface of the thyroid gland
- > parathyroid cells secrete parathyroid hormone (PTH)
Functions of parathyroid hormone
*Opposite function as calcitonin*
Raises blood calcium levels by…
- > increasing activity of osteoclasts
- > increases reabsorption of Ca by Kidneys
- > promotes formation of calcitriol (Vitamin D) by kidneys and liver which increases absorption of Ca by intestinal track
Function of calcitonin
*Opposite function of parathyroid hormone*
- > decreases blood calcium levels to make bone matrix during growth
Dectribe the process of increasing/ decreasing blood Ca levels
What/ where are the adrenal glands
Paired glands anchored on the superior border of the kideys; also called suprarenal glands
Explain the structure of the adrenal glands
They’re divided functionally into an outer adrenal cortex and an inner adrenal medulla
Explain the three layers of the adrenal cortex
- Zona glomerulosa - > mineralocorticoids (aldosterone) secreted in response to low blood pressure, signals kidney to absorb more Na and water
- Zona fasciculata - > glucocorticoids (cortisol) secreted in response to stress, raises blood sugar levels; also used as an anti-inflamatory agent (over-use reduces immune response)
- Zona reticularis - > produces the sex hormones (estrogen, testosterone-related hormones)
Explain the function ofthe adrenal medulla
- > chromaffin cells receive direct innervation form sympathetic nervous system
- > produces catecholamines: Epinepherine(adrenaline) and Norepinephrine (noradrenaline; increases and maintains BP)
- > hormones are sympathomimetic (effects mimic those of sympathetic NS; causes fight/ flight response)
General characteristic of Pancreas
- > has both hormone (endocrine,ductless) and digestive (exocrine, ducted) functions
- > located upper left abdomen, posterior to stomach
- > has ducts leading into lumen of small intestine
Anatomy of Pancreas
- > 98-99% of pancreatic cells are pancreatic acinin (produced alkaline pancreatic secretions into ducts; exocrine)
- > 1-2% of cells are small clusters of endocrine cells called pancreatic islets (islets of Langerhans); regulate blood glucose
Cell types in Islets of langerhans
Alpha cells (20%) - > produce glucagon (increases blood sugar levels)
Beta Cells (70%) - > produces insulin (decreases blood sugar levels)
Delta cells (5%) - > produces somatostatin (reduces secretion of alpha and beta cells)
F cells - > produces pancreatic polypeptides (inhibits exocrine/digestive part of pancreas)
Functions of ovaries
- > estrogen, progesterone, relaxin, inhibin
- > regulate reproductive cycle, maintain pregnancy and prepare mammary glands for lactation
Function of Testes
- > interstitial cells produce testosterone
- > regulate sperm production and 2nd sexual characteristics (adams apple, body hair)
Functions of pineal gland
*located in the posterior region of the epithalamus*
- > secretes melatonin, which is involved in maintaining the 24-hour circadian cycle (day cycle) and sexual matruation
Effect of light on pineal gland
What is seasonal affective disorder; how does it work?
- > depression that occurs during winter months when day length is short
- > due to overproduction of melatonin
- > exposure to artificial sunlight can speed recovery
Explain jet lag
When your circadian cycle is thrown off and your body thinks it’s daytime when it’s night time or vice versa
- > exposure to artificial sunlight can speed recovery
Relaxin and Inhibin
Relaxin - > relax joints for child birth
Inhibin - > inhibit the production of follicle-stimulating hormone (FSH) by the pituitary gland
