Endocrine System Flashcards
1
Q
Glands in which ducts carry secretions to surface or organ cavity and have extracellular effects such as food digestion
A
Exocrine Glands
2
Q
Glands without ducts which secrete hormones into tissue fluids, capillary networks and the bloodstream
A
Endocrine Glands
Secretions have intracellular effects, altering cell metabolism
3
Q
What is the general function of the endocrine system?
A
Controlling and integrating the function of other organ systems via hormones
4
Q
What is the difference in nervous vs. endocrine communication?
A
nervous - electrical and chemical signals
endocrine - chemical signals only
5
Q
What is the difference in nervous vs. endocrine response speed and effect persistence?
A
nervous - quick reaction (milliseconds), effect stops quickly
endocrine - slow reaction (seconds to days), effect may continue for weeks
6
Q
What is the difference between nervous vs. endocrine adaptation to long-term stimuli?
A
nervous - adapt quickly and response declines
endocrine - response persists
7
Q
The 3 Main Endocrine System Components
A
- Endocrine Glands
- Hormones
- Target Cells
8
Q
Hormone
A
- a chemical “messenger” molecule secreted into the bloodstream which stimulates a response in another tissue or organ
9
Q
Target Cells
A
- cells with receptors for a certain hormone
(ex: thyroid cells are target cells for TSH secreted by the anterior pituitary)
10
Q
Receptor Site
A
the site on a cell membrane or in its cytoplasm/nucleus to which a hormone binds
11
Q
Three Types of Endocrine Glands
A
- Pure endocrine
- Endocrine/exocrine (mixed)
- “Neuroendocrine” glands
12
Q
Pure Endocrine Glands
A
- thyroid
-parathyroid
- adrenal cortex
- thymus
- pineal gland
13
Q
Endocrine/Exocrine (Mixed) Glands
A
- pancreas
- ovaries
- testes
14
Q
“Neuroendocrine” Glands
A
- Adrenal medulla
- Hypothalamus
- Posterior pituitary
- contain specialized nervous cells which produce hormones
15
Q
A
Hypothalamus
- directly below thalamus in diencephalon
- composed of several groups of nuclei ( neurons & neuroglia)
- regulates anterior pituitary hormones
- sends ADH and Oxytocin to posterior pituitary for storage and future release
16
Q
What is this entire structure?
A
Pituitary Gland (AKA Hypophysis)
- sits in sella turcica of sphenoid bone
- attaches to hypothalamus via the infundibulum
- secretes nine homeostatic hormones
- two lobes: Adenohypophysis (Anterior, “adeno” = glandular) and Neurohypophysis (Posterior, “neuro” = neural)
17
Q
What is #4 and what hormones does it secrete?
A
Anterior Pituitary (AKA Adenohypophysis)
- releases 7 hormones:
- Growth Hormone (GH)
- Prolactin (PRL)
- Thyroid-stimulating Hormone (TSH)
- Adrenocorticotropic Hormone (ACTH)
- Melanocyte-Stimulating Hormone (MSH)
- Follicle-Stimulating Hormone (FSH)
- Luteinizing Hormone (LH)
18
Q
What is #6 and what hormones does it secrete?
A
Posterior Pituitary (AKA Neurohypophysis)
- Secretes 2 hormones:
- Anti-diuretic Hormone (ADH) (AKA Vasopressin)
- Oxytocin
19
Q
What is the fancy latin name for #4?
A
pars distalis
20
Q
What’s the fancy latin name for #6?
A
pars nervosa
21
Q
A general name for hormones that stimulate other endocrine glands and the 4 of them secreted by the anterior pituitary
A
Tropic Hormones
- TSH
- ACTH
- FSH
- LH
22
Q
A general name for hormones that stimulate the gonads and the two secreted by the anterior pituitary
A
gonadotropins
- FSH
- LH
23
Q
follicle-stimulating hormone
A
- stimulates production of egg or sperm cells
24
Q
Luteinizing Hormone
A
- stimulates hormone production
males - stimulates interstitial teste cells to secrete testosterone
females - stimulates ovulation and corpus luteum to secrete progesterone and estrogen
25
Thyroid-Stimulating Hormone
- stimulates growth of thyroid gland and secretion of TH
26
Adrenocorticotropin Hormone
- regulates stress response by stimulating adrenal cortex
27
Prolactin
females - stimulates milk **synthesis** after childbirth
males - increases LH sensitivity, thus increasing testosterone secretion
28
Growth Hormone
AKA **Somatotropin**
- promotes tissue growth
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Melanocyte Stimulating Hormone
- involved in skin pigmentation
30
How does the hypothalamus regulate the adenohypophysis?
Via **releasing** and **inhibiting hormones** sent through the **hypothalamo-hypophyseal portal system**
31
What is a portal system?
- a system in which blood moves from organ to organ without first passing through the heart
32
What is #9?
Primary capillaries
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What is # 2?
Portal Venule
- between hypothalamus and adenohypophysis
34
What is part #4?
Secondary capillary bed
| (in adenohypophysis)
35
What is #6? And what hormones does it secrete?
**Posterior Pituitary** (AKA **Neurohypophysis**)
- secretes **two hormones**: **ADH** and **Oxytocin**
36
ADH
**Anti-Diurectic Hormone** (AKA **Vasopressin**)
- produced in hypothalamus, sent to neurohypophysis, secreted from there
- **targets kidneys** to **increase water retention**, **reduce urine** and **increase blood pressure**
- functions as **neurotransmitter**
37
Oxytocin
- produced in hypothalamus, sent to neurohypophysis, secreted from there
- stimulates **lactation** and **labor contractions**
- possible role in **sperm transport** and **emotional bonding**
38
How does the hypothalamus communicate with the posterior pituitary?
Via the **hypothalamo-hypophyseal tract,** a **neural connection** between the two glands
- neuron cell bodies in the hypothalamus transport ADH and oxytocin via their axons to a capillary bed in the neurohypophysis
39
**thyroid gland**
- the largest endocrine gland
- secrete **thyroid hormones** which increase metabolic rate, etc.
- located anterior and laterally to trachea, inferior to larynx
- two lobes connected by the **isthmus**
- bulbous inferiorly, tapered superiorly
40
the central part connecting the two sides of this gland
**Isthmus** of the thyroid gland
41
#1 (whole structure, not just cells lining it)
**Thyroid Follicle**
- microscopic pockets within thyroid filled with **colloid** and lined with simple cuboidal epithelial cells which release **T3** and **T4**
42
What are the thyroid hormones and what do they do?
**T3** (tri-iodothyronine) and **T4** (thyroxine)
* increase metabolic rate and O2 consumption
* increase heat production via calorigenic effect
* increase heart rate and contraction strength
* increase respiratory rate
43
#2 (the liquid within, not the structure)
**Colloid**, AKA **thyroglobulin**
- fluid within thyroid follicles containing precursors to thyroid hormones
44
#4
**Parafollicular Cells** (AKA **Calcitonin** or **C Cells**)
- found between cuboidal follicular cells
- produce **calcitonin**
45
Calcitonin
- hormone produced by parafollicular cells of thyroid
- Decreases blood Ca2+, promotes Ca2+ deposition and bone formation (via osteo**_blast_** activity)
46
square cells lining circular structures here:
**follicular cells**
- simple cuboidal epithelium
- produce thyroid hormones
47
green structure
**Pineal Gland** (or body)
- located in the posterior roof of the diencephalon
- produces **melatonin**, which regulates sleep cycles
- may play a role in the onset of puberty
48
Small, pinto bean-like structures on the surface of the larger structure. (Posterior view)
**Parathyroid Glands**
- located on posterior surface of thyroid
- usually 4, up to 8
- produce **parathormone (PTH)** in their **chief cells**
49
Parathormone
AKA **Parathyroid hormone** or **parathyrin**
- secreted by **chief cells** of parathyroid
function:
* increase blood Ca2+ levels
* promotes synthesis of **calcitriol** (active form of vitamin D), thereby...
* increasing digestive absorption of Ca2+
* decreasing urinary excretion of Ca2+
* increasing bone resorption (via osteo**_clasts_**)
50
Calcitriol
- active form of vitamin D synthesized in the kidney when stimulated by PTH
- increases Ca absorption and bone resorption, decreases Ca excretion, thus increasing blood Ca
- opposes action of Calcitonin from parafollicular cells of thyroid
51
What is the left structure composed of more densely packed cells? And what are its cells called?
**parathyroid gland**
**chief cells -** synthesize parathormone
52
The top, unlabeled lumpy structures
**Adrenal Glands**
- triangular gland embedded in adipose tissue on **superior surface of kidneys**
- almost entirely **sympathetic innervation**
- "two glands in one" - **adrenal medulla** deep to **adrenal cortex**
53
pink interior portion of magnified gland
**adrenal medulla**
- **neuroendocrine** tissue
- **_Chromaffin Cells_** - **modified postganglionic sympathetic cells** division of ANS
- create and secrete **Epinephrine**, **Norepinephrine** and some **Dopamine**
- **exception** to long postganglionic axon rule in sympathetic ANS, **preganglionic sympathetic fiber runs into medulla**
54
epinephrine and norepinephrine
- hormones produced and secreted by Chromaffin cells of the adrenal medulla
- have some different effects but generally contribute to **fight-or-flight** response:
* increase heart rate and BP
* constrict skin and GI blood vessels
* dilate smooth muscle
* increase metabolism
55
distinct layer of more randomly arranged cells in right half of image sandwiched between two layers of cells arranged in strands
**adrenal medulla**
(chromaffin cells in spherical clusters)
56
Chromaffin Cells
- cells of the adrenal medulla which synthesize epinephrine or norepinephrine
57
58
Outer layer of gland indicated by pointer
**adrenal cortex**
- glandular tissue of adrenals
- makes up bulk of adrenal gland
- secretes **corticoid hormones**
59
The 3 Types of Corticoid Hormones, Where They Are Synthesized and Examples of Each
1. **Mineralocorticoids** from the **Zona glomerulosa,** specifically **Aldosterone**
2. **Glucocorticoids** from the **Zona Fasciculata**, specifically **Cortisol**
3. **Gonadocorticoids** from the **Zona Reticularis,** specifically **androgens and testosterone**
60
#2
**Zona **_glomerul_**osa** of adrenal cortex
- round arrangements of cells
- make **mineralocorticoids**, ex: aldosterone
61
#3
**Zona **_Fascicul_**ata**
- middle, largest layer of adrenal cortex
- **parallel cords** of lipid-rich cells
- appear "bubbly" and usually stain lighter than other layers
- creates **glucocorticoids**, ex: **cortisol**
62
#4
**zona **_reticul_**aris**
- innermost cortical layer next to adrenal medulla
- narrow band of **small, branching cells**
- produce **gonadocorticoids**, ex: androgens/testosterone
63
yellow-white structure extending rightward from the duodenum:
Pancreas
- just inferior to stomach in posterior wall of ab. cavity
- **mixed exocrine/endocrine** gland
- **exocrine** cells produce **digestive enzymes**
- **endocrine** cells grouped into **Islets of Langerhans,** which secrete hormones including:
* **Glucagon**
* **Insulin**
* **Somatostatin**
* **Pancreatic polypeptide**
64
Glucagon
- secreted by **alpha cells** of **pancreatic islets**
- signals the liver to **break down glycogen** into glucose
65
Insulin
- secreted by **beta cells** of pancreatic islets
- signals cells to take up glucose, **controls blood sugar** levels
66
Somatostatin
- released by **delta cells** of pancreatic islets
- **decreases insulin & glucagon** release
- **decreases growth hormone** release
67
Pancreatic Polypeptide
- secreted by **F cells** (AKA **PP cells**) of pancreatic islets
- **decreases pancreatic exocrine activity**
68
cluster of lighter cells in the middle
**Pancreatic Islet** (AKA **Islet of Langerhans**)
- groupings of endocrine cells within the pancreas
- five kinds of cells:
* **alpha cells** (glucagon)
* **beta cells** (insulin)
* **delta cells** (somatotropin)
* **F cells** (pancreatic polypeptide)
* **epsilon cells** (ghrelin)
69
leftmost dark pink area
**anterior pituitary**
- densely packed cells
70
middle lighter pink area marked PN
**posterior pituitary (pars nervosa)**
- unmyelinated axons + neuroglia
71
#4
**Thymus**
- produces hormones **thymopoietin** and **thymosins** which regulate development and maintenance of **immune function**
72
paired almond-shaped organs on either side of uterus
**Ovaries**
- primary female sex organ
- located retroperitoneally in abdomen, lateral to uterus at proximal end of fallopian tubes
- produce female sex hormones **estrogen** and **progesterone** and **contain ova**
73
**Testes**
- male sex organ located in scrotum
- secrete **androgens (testosterone)** and **inhibin**
- produces **sperm cells**
74
Female gametes surrounded by estrogen-producing cells
**Follicles**
- **eggs** surrounded by **granulosa cells**
75
smaller cells surrounding large central cell
**Granulosa Cells**
- cells within ovaries that produce **estrogen**
76
