Endocrine Flashcards
1
Q
Hormones
A
- hormones are released into the blood
- chemical messengers that change metabolic activity of another cell
- cells with receptors are target cells/target organs
2
Q
Protein (peptide) hormones
A
- formed from chains of amino acids
- Ex: growth hormone
3
Q
Biogenic amines (amino acid derivatives)
A
- formed by altering the structure of a specific amino acid
- ex: thyroid hormones
4
Q
Steroid hormones
A
- type of lipid derived from cholesterol
- ex: estrogen, testosterone, cortisol
5
Q
What do the nervous and endocrine systems do?
A
- work together to regulate homeostasis
- both affect specific target cells using chemical messengers
- chemical messengers: chem that goes from one part of the body to another
6
Q
Nervous System Only
A
- uses nerve impulses along axons to reach target
- rapid response to stimulus
- localized, specific effects (ex: a specific muscle contracts)
- response lasts a short time (milliseconds)
> ex: contracting and the deconstructing muscles
7
Q
Endocrine System Only
A
- uses hormones that are transported via blood to their targets
- relatively slow response
- widespread effects throughout body (ex: testosterone affects facial hair, acne, muscle growth, sexual response, etc)
- response lasts longer time (minutes, days, weeks…)
8
Q
Negative Feedbacks Loops
A
- hypothalamus detects low levels of hormone
- hypothalamus tells pituitary to fix low levels
- pituitary tells organ to produce hormone
- organ produces hormone
- now there’s enough hormone in the blood
- hypothalamus detects enough hormone in blood
9
Q
Positive Feedback Loop
A
- initial stimulus to endocrine system
- pituitary releases hormone
- hormone affects target
- prescience of hormone acts as stimulus to release more hormone
10
Q
The Hypothalamus
A
- “control center” of endocrine system
- the hypothalamus regulates endocrine system in 3 ways:
- Signals to anterior pituitary
- Signals to posterior pituitary
- Direct stimulation of adrenal cortex —> part of adrenal
glands
11
Q
The Pituitary (Hypophysis)
A
- pituitary located in sella turcica of sphenoid bone
- anterior pituitary (adenohypophysis) :extensive vascular network, secretes 7 hormones in response to regulatory hormones secreted by the hypothalamus
- posterior pituitary (neurohypophysis): secretes only two hormones
- connected to the hypothalamus by infundibulum
12
Q
Hypothalamus to Anterior Pituitary
A
- hypothalamus secretes regulatory hormones
> turn on, turn off and they regulate - regulatory hormones stimulate anterior pituitary to secrete seven different hormones
Seven Hormones:
1. Thyroid stimulating hormone (TSH)
2. Adrenocorticotropic hormone (ACTH)
3. Follicle stimulating hormone (FSH)
4. Luteinizing hormone (LH)
5. Prolactin (PRL)
6. Growth hormone (GH)
7. Melanocyte stimulating hormone (MSH)
13
Q
hypothalamus to posterior pituitary
A
- neurons from hypothalamus stimulate cells in posterior pituitary
- posterior pituitary releases
- Vasopressin: restricts water loss in kidneys
- Oxytocin: involved in uterine contraction during birth, sexual response, milk ejection reflex
14
Q
Thyroid Gland
A
- two lobes connected by an isthmus (butterfly-shaped)
- anterior to trachea
- extensive blood supply (very vulnerable in surgery)
15
Q
How does the thyroid gland work?
A
- hypothalamus releases regulatory hormone to anterior pituitary
- anterior pituitary releases thyroid stimulating hormone (TSH)
- TSH stimulates thyroid to release T3 and T4 (thyroid hormones)
16
Q
Thyroid gland histology
A
- thyroid follicles lined by follicular cells
- follicular cells secrete T3 and T4
> influence metabolic rate and protein synthesis
> widespread targets (gut, heart) - parafollicular cells release calcitonin, which regulates calcium homeostasis
17
Q
Parathyroid Glands
A
- four small glands located on posterior aspect of thyroid gland
18
Q
How parathyroid glands work?
A
- low blood calcium
- stimulates chief cells in parathyroid glands to release parathyroid hormone
- targets: increased osteoclast activity, kidney retains calcium
19
Q
Suprarenal glands
A
- attached to superior aspect of kidneys
- divided into suprarenal cortex and suprarenal medulla
20
Q
Suprarenal Glands: Suprarenal Cortex
A
- secretes 24 different corticosteroids, divided into:
- mineralocorticoids: influence electrolyte composition (ex: aldosterone targets kidneys to fine tune electrolytes)
- glucocorticoids: influence glucose metabolism (ex: cortisol targets liver to convert glycogen to glucose)
21
Q
How suprarenal cortex works?
A
- hypothalamus releases RH to anterior pituitary
- anterior pituitary releases adrenocotropic hormone (ACTH)
- ACTH stimulates release corticosteroids from adrenal gland
22
Q
Suprarenal Glands: Suprarenal Medulla
A
- cells suprarenal medulla resemble sympathetic ganglia
- innervated by preganglionic sympathetic fibers (axons)
- secrete epinephrine and norepinephrine
- effects are similar to “activation” but last longer
- takes a min to calm down bc suprarenal medulla has released cortisol —> floating around in the blood
23
Q
How does the suprarenal medulla work?
A
- hypothalamus directly innervates suprarenal medulla with preganglionic sympathetics
- adrenal medulla secretes epinephrine and norepinephrine to widespread target s
24
Q
Pancreas
A
- mixed gland in abdominal cavity with:
> exocrine parts that secrete digestive juices
> endocrine parts that secrete hormones
25
alpha cells of the pancreas
- produce glucagon
- raises blood glucose
- targets liver to initiate glucogenesis
- if you have too little blood sugar
26
Beta cells of pancreas
- produce insulin
- decreases blood glucose
- targets liver, skeletal muscle, adipose tissue to increase uptake of glucose by cells
- too much blood sugar
27
How does it work if the blood glucose is too low?
- stimulates pancreatic alpha cells to release glucagon
- targets liver to begin process of gluconeogenesis (makes glucose)
28
How does it work if the blood glucose is too high?
- stimulates pancreatic beta cells to release insulin
- targets liver, skeletal muscle, adipose tissue to increase glucose uptake
29
Testis
- interstitial cells of the testis produce androgens
- androgens (ex: testosterone) have widespread effects (ex: facial hair, sexual function, muscular development, etc)
30
How do the testis work?
- hypothalamus releases RH to anterior pituitary
- anterior pituitary releases luteinizing hormone (LH) and follicle stimulating hormone (FSH)
- LH stimulates production of androgens
- FSH stimulates development of sperm
31
Ovary
- follicle cells surround oocytes and produce estrogen
- follicle cells merge w/ ovary and then ovulation happens
- after ovulation, follicular cells form corpus lutem, which produces progesterone
32
How does it work for the ovary with FSH?
- hypothalamus releases RH to anterior pituitary
- anterior pituitary releases follicle stimulating hormone (FSH)
- FSH stimulates estrogen secretion: growth of ovarian follicle, maturation of oocyte, growth of uterine lining
33
How does it work for the ovary with luteinizing hormone?
- hypothalamus releases RH to anterior pituitary
- anterior pituitary releases luteinizing hormone
- LH stimulates ovulation
> LH stimulates progesterone secretion by corpus luteum:
lining of uterus shifts to secretory phase
