Human Anatomy CH 17 Flashcards
What system interacts closely with the nervous system?
Endocrine system
What are the organs of the endocrine system and what did they secrete?
- Disperse group of ductless glands
- Messenger molecules called hormones
What is the study of hormones and endocrine glands?
Endocrinology
Which 5 endocrine organs are pure endocrine organs?
(HINT: One of them has 2 parts)
- Pituitary Gland
- Pineal Gland
- Thyroid Gland
- Parathyroid Gland
- Adrenal Gland - Adrenal Cortex + Adrenal Medulla
Which 4 organs contain a large proportion of endocrine cells?
(HINT: Which is specifically part of the brain?)
- Pancreas
- Thymus
- Gonads
- Hypothalamus - neuroendocrine organ
Which 4 organs contain some endocrine cells? What kind of origin is the endocrine cells?
- Heart
- Digestive Tract
- Kidneys
- Skin
Endocrine cells are of epithelial origin
What are the 2 classes of hormones? What are they derived from?
- Amino acid-based hormones
- Steroids - derived from cholesterol
What are 3 basic hormone actions?
- Circulate throughout the body in blood vessels
- Influence only specific tissue cells called target cells
- A hormone can have different effects on different target cells
Secretion is triggered by what 3 major types of stimuli?
- Humoral
- Neural
- Hormonal
What 3 things does Humoral stimuli do?
- Simplest of endocrine control mechanisms
- Secretion in direct response to changing ion or nutrient levels in the blood
- Parathyroid monitors calcium and responds to decline by secreting hormone to reverse decline
What 2 things does Neural stimuli do?
- Sympathetic nerve fibers stimulate cells in the adrenal medulla
- Induces release of epinephrine and norepinephrine
What 2 things does Hormonal stimuli do?
- Stimuli received from other glands
- Certain hormones signal secretion of other hormones
The hypothalamus secretes hormones. What do these hormones do?
- Stimulate pituitary
- Stimulate other glands
What is hormonal secretion controlled by?
Feedback loops
More hormone is secreted when? Hormone production is halted when?
- Blood concentration declines below a minimum
- Blood concentration exceeds maximum
What does tropic mean?
Hormone causes another gland to release another hormone
What are the 9 hormones secreted by the pituitary gland?
- FSH
- LH (Luteinizing hormone)
- ACTH (Adrenocorticotropic hormone)
- TSH (Thyroid-Stimulating hormone)
- PRL (Prolactin)
- GH (Growth hormone)
- MSH (Melanocyte-stimulating hormone)
- ADH (Anti-diuretic hormrone)
- Oxytocin
The pituitary gland is attached to the hypothalamus via what?
Infundibulum
What are the 2 basic divisions of the pituitary gland?
- Anterior lobe (adenohypophysis)
- Posterior lobe (neurohypophysis)
How many divisions does the anterior lobe have? What are they?
3 major divisions:
1. Pars distalis
2. Pars intermedia
3. Pars tuberalis
How many divisions does the posterior lobe have? What are they?
2 major divisions
1. Pars nervosa
2. Infundibulum
What is the largest division of the anterior lobe?
Pars Distalis
The pars distalis contains how many endocrine cells? It makes and secretes how many hormones?
Contains 5 different endocrine cells
Makes and secretes 7 different hormones
What do tropic hormones do? What 4 hormones are tropic hormones?
Regulate hormone secretion by other glands
TSH, ACTH, FSH, and LH
What 3 hormones act directly on nonendocrine target tissues?
GH, PRL, and MSH
Thyroid-stimulating hormone is produced by what cells? What do these cells do?
- Thyrotropic cells
- Signals thyroid gland to secrete thyroid hormone
What does adrenocorticotropic hormone do?
Stimulates adrenal cortex to secrete hormones that help cope with stress
What do gonadotrophic cells produce? What 2 hormones fall under this category?
Gonadotrophins
1. FSH
2. LH
Growth hormone is also known as?
Somatotropic hormone
What are the 2 functions of growth hormone?
- Stimulates body growth by stimulating increased protein production and growth of epiphyseal plates
- Stimulates growth directly and indirectly by the liver’s secretion of insulin-like growth factor-1
What does melanocyte-stimulating hormone do in humans?
Appetite suppression
Somatotropic cells produce?
Growth hormone (somatotropic hormone)
Prolactin is produced by what cells? What does this hormone target and what is its function?
Prolactin cells
Targets milk-producing glands in the breast and stimulates milk production
What are endocrine cells in the pars distalis like?
Clustered in spheres and branching cords
What are the 5 cell types of the anterior lobe classified as?
(HINT: Only 3 classifications)
- Acidophils
- Basophils
- Chromophobes
What controls secretion of anterior lobe hormones?
Hypothalamus
What does the hypothalamus secrete to exert control over the anterior lobe? What do these hormones do respectively?
- Releasing hormones - prompts anterior lobe to release hormones
- Inhibiting hormones - turns off secretion of anterior lobe hormones
Releasing hormones are secreted like?
Neurotransmitters
What is the path that releasing hormones travel?
Enters primary capillary plexus —> travels in hypophyseal portal veins to secondary capillary plexus —-> hormones secreted by anterior lobe enter general circulation and travels to target organs
Is the posterior lobe of pituitary gland structurally part of the brain?
Yes
What do the axons of the posterior lobe make up?
Hypothalamohypophyseal tract
The hypothalamohypophyseal tract arises from what and in which part of the body?
Neuronal cell bodies in the hypothalamus
What 2 types of regions of the hypothalamus make up the hypothalamohypophyseal?
- Supraoptic nucleus
- Paraventricular nuclear
What are the 2 main functions of the posterior lobe? What does it NOT do?
- Stores and releases hormones made in hypothalamus
- Does not make hormones
What 2 peptide hormones does the posterior lobe release?
- ADH
- Oxytocin
What is another name for ADH that is NOT antidiuretic hormone?
Vasopressin
Where is ADH made? What is its function?
- Supraoptic nucleus
- Targets kidneys to resorb water
Where is oxytocin made? What is its function?
- Paraventricular nucleus
- Induces smooth muscle contraction of reproductive organs, ejects milk during breast-feeding, and signals contraction of the uterus during childbirth
What is the largest purely endocrine gland? Where is it located?
Thyroid Gland; located in anterior neck
What is the thyroid gland composed of? What 2 hormones does it produce?
Composed of follicles and areolar connective tissue
1. Thyroid Hormone (TH)
2. Calcitonin
Where are the parathyroid glands?
Lie on posterior surface of thyroid gland
What are the 2 types of endocrine cells that the parathyroid glands produce? What are their functions?
- Chief cells - Produce parathyroid hormone (PTH) and increases blood concentration of Ca2+
- Oxyphil cells - function unknown
What are the pyramid-shaped glands located on the superior surface of each kidney called?
Adrenal (suprarenal) glands
The adrenal glands are supplied by how many suprarenal arteries?
60 suprarenal arteries
The Adrenal gland’s nerve supply is almost exclusively _______
sympathetic fibers
What is the cluster of neurons in the adrenal glands? What is it derived from and what system is it a part of?
Adrenal Medulla
Derived from: Neural crest
Part of sympathetic nervous system
What do all adrenal hormones help with?
Helps body cope with danger, terror, or stress
What forms the bulk of the adrenal gland? What is it derived from?
Adrenal Cortex
Derived from: Somatic mesoderm
What are modified postganglionic sympathetic neurons called?
Medullary chromaffin cells
Medullary chromaffin cells secrete what type of hormones?
(HINT: There’s 2 of them)
Amine hormones
1. Epinephrine
2. Norepinephrine
What do epinephrine and norepinephrine do? Where are they stored?
Enhances “fight-or-flight” response
Stored in secretory vesicles
How are epinephrine and norepinephrine arranged and stored?
Arranged in spherical clusters and some branching cords
What does the Adrenal Cortex secrete? What is the alternate name for them?
Secretes lipid-based steroid hormones
Corticosteroids
What are the 3 layers (zones) of the adrenal cortex? How is each one arranged?
- Zona glomerulosa - cells arranged in spherical clusters
- Zona fasciculata - cells arranged in parallel cords
- Zona reticularis - cells arranged in branching network
What are the 2 main classes of adrenal corticosteroids?
- Mineralocorticoids
2.Glucocorticoids
What is a mineralocorticoid that is secreted by the zona glomerulosa?
Aldosterone
Aldosterone is secreted in response to?
In response to decline in blood volume or blood pressure
Aldosterone is the terminal hormone of what mechanism?
Terminal hormone of renin-angiotensin mechanism
Which adrenal cortex zone contains lipid droplets?
Zona fasciculata
What is the main type of glucocorticoid?
Cortisol
What 2 zones of the adrenal cortex secretes cortisol?
- Zona fasciculata
- Zona reticularis
What does the cortisol help with?
Helps body deal with stressful situations
What is the small pinecone-shaped gland called? Where is it located?
Pineal Gland located on roof of diencephalon
What within the pineal gland is arranged in spherical clusters and branching cords? What do they secrete?
Pinealocytes; secretes melatonin
What is a characteristic of “pineal sand”?
Radiopaque
What is pineal sand used for?
Used as a landmark to identify other brain structures in X-ray films
What is melatonin used for?
Regulates circadian rhythm
What is located in the posterior abdominal wall?
Pancreas
What kind of cells does the pancreas contain?
(HINT: There’s 2)
Endocrine and exocrine cells
What is another name for exocrine cells of the pancreas? What does it secrete?
Acinar cells - secretes digestive enzymes
What is another name for endocrine cells of the pancreas? How many are there?
Pancreatic islets
About 4 million islets
What are the 2 main cell types of the pancreas? What do they secrete?
Alpha cells - secrete glucagon
Beta cells - secrete insulin
What are the 2 main functions of glucagon?
- Signals liver to release glucose from glycogen
- Raise blood sugars
What are the 3 main functions of insulin?
- Signal most body cells to take up glucose from the blood
- Promote storage of glucose as glycogen in liver
- Lower blood sugars
What are the 2 rare cell types found in pancreatic islets? What do they secrete?
Delta cells - secrete somatostatin
F cells - secrete pancreatic polypeptide
What is the function of somatostatin?
Inhibits secretion of insulin and glucagon
What is the function of pancreatic polypeptide?
May inhibit exocrine activity of the pancreas
What is located in the lower neck and anterior thorax?
Thymus
Is the thymus an important immune organ?
Yes
The thymus is the site at which what occurs?
Site at which T lymphocytes arise from precursor cells
The transformation of _______ is stimulated by _________
The transformation of lymphocytes is stimulated by thymic hormones
Thymic hormones are also known as?
Peptide molecules
What are 2 types of thymic hormones?
- Thymopoietin
- Thymosin
The gonads are the main sources of ________. What are the 2 main gonads?
Sex hormones
1. Ovaries
2. Testes
What disorder is the hypersecretion of GH in children?
Gigantism
What disorder is the hyposecretion of GH?
Pituitary Dwarfism
What disorder is when the pars nervosa doesn’t release enough ADH?
Diabetes insipidus
What kind of disorders do Gigantism, Pituitary Dwarfism, and Diabetes Insipidus fall under?
Pituitary Disorders
What endocrine organ does diabetes affect?
Pancreas
What is Diabetes Mellitus caused by?
(HINT: 2 causes)
- Insufficient secretion of insulin
- Resistance of body cells to the effects of insulin
What disorder is when a T cell-mediated autoimmune response destroys beta cells?
Type 1 Diabetes
When does Type 1 diabetes develop?
Develops suddenly, usually before age 15
What disorder is when cells have lowered sensitivity to insulin?
Type 2 Diabetes
When does Type 2 diabetes develop?
Adult onset, usually occurs after age 40
What can help control Type 2 diabetes?
Dietary changes and regular excercise
What is the most common type of hyperthyroidism?
Graves’ Disease
What happens when someone if afflicted with Graves’ disease?
Immune system makes abnormal antibodies which stimulate the oversecretion of TH by follicle cells
What are the symptoms of Graves’ disease?
Nervousness, weight loss, sweating, and rapid heart rate
What is the disorder known for adult hyperthyroidism?
Myxedema
What happens when someone is afflicted with Myxedema?
Antibodies attack and destroy thyroid tissue
What are common symptoms of Myxedema?
Low metabolic rate and weight gain
What disorder is due to lack of iodine in the diet?
Endemic goiter
What is hypothyroidism in children called?
Cretinism
What are the symptoms of Cretinism?
Short, disproportionate body, thick tongue, and mental retardation
What disorder is caused by hypersecretion of glucocorticoid hormones?
Cushing’s Syndrome
Graves’ Disease, Myxedema, Endemic goiter, and Cretinism are all disorders of what gland?
Thyroid Gland
Addison’s disease is what kind of disorder? What is it a deficiency of?
Addison’s Disease; deficiency of mineralocorticoids and glucocorticoids
Cushing’s Syndrome and Addison’s Disease are both caused by what part of the endocrine system?
Adrenal Cortex
Where does the thyroid gland form from?
Forms from thickening of endoderm on floor of pharynx
Where does the parathyroid and thymus gland form from?
Forms from endoderm lining the pharyngeal pouches
What does the pineal gland originate from?
Originates from ependymal cells
Where does the pituitary gland originate from?
(HINT: One for adenohypophysis and one for neurohypophysis)
- Adenohypophysis originates from roof of mouth
- Neurohypophysis grows inferiorly from floor of brain
Where does the adrenal gland originate from?
(HINT: One for adrenal medulla and one for adrenal cortex)
- Adrenal Medulla - From neural crest cells of nearby sympathetic trunk ganglia
- Adrenal Cortex - From mesodermal lining of coelum
For how long does the endocrine organs function for within the human lifespan?
Operates effectively until old age
As the anterior pituitary ages, what happens to it?
(HINT: 2 things occur)
- Increase in connective tissue and lipofuscin
- Decrease in vascularization and number of hormone-secreting cells
As the adrenal cortex ages, what happens to it?
Normal rates of glucocorticoid secretion continue
As the adrenal medulla ages, what happens to it?
No age-related changes in catecholamines
As the thyroid hormones age, what happens to it?
Decreases slightly with age
As the parathyroid glands age, what happens to it?
Little change with aging
As FH, DHEA, and sex hormones age, what happens to them?
Marked drops in secretion with age
