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Histo second semester 23-24 > Histo endocrine sys I > Flashcards

Histo endocrine sys I Flashcards

1
Q

What is the function of the endocrine system

A

Regulates metabolic activity of target organs and tissues, using chemical substances called hormones. Regulates functions, homeostasis and coordination of body growth and development and fucntions along with the Nervous system

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2
Q

The endocrine system consists of?

A

*Endocrine glands: the pituitary gland, the thyroid gland, the parathyroid glands and the suprarenal glands.
*Clusters of cells within certain organs (e.g. Islets of Langerhans)
*Endocrine cells (isolated in the epithelium of digestive and respiratory systems)

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3
Q

general characteristics of endocrine glands

A

–Absence of excretory ducts, they go straight to capilaries when exocytosed
–Highly vascularized
–Cell arranged in cords

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4
Q

explain endocrine secretion

A

Hormone released into blood or lymph vessels, then transported to another part of body, where it acts on target tissues or organs.

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5
Q

explain paracrine secretion

A

Hormone released into immediate vicinity. Neuroendocrine system consist of cells scattered throughout digestive and respiratory systems. when the cell that releases th ehormones responds to herself, is called autocrine

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6
Q

hormone secreting cells that regulate the function an activity of organs are called?

A

Diffuse Neuroendocrine Sysstem (DNES)

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7
Q

WHY IS ADIPOSIDE TISSUE IMPORTANT?

A

Also adipose tissue is an important hormonally active tissue that secrets a variety of hormones, growth factors, and cytokines, collectively called adipokines.

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8
Q

what are the 3 classes of hormones of the endocrine system?

A
  1. peptides (small peptides, polypetides, proteins)
  2. steroids, cholesterol-derived
  3. amino acids and arachidonic acid
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9
Q

describe peptides

A

This group of hormones (insulin, glucagon, growth hormone [GH], adrenocorticotropic hormone [ACTH], follicle-stimulating hormone [FSH], luteinizing hormone [LH], antidiuretic hormone [ADH], oxytocin, interleukins, and various growth factors. These hormones do not require special transport proteins. However, most, if not all, polypeptides and proteins have specific carrier proteins (e.g., insulin growth factor–binding protein [IGFBP]).

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10
Q

describe steroids

A

synthesized and secreted by cells of the ovaries, testes, and adrenal cortex. These hormones are transported to target cells by plasma proteins or specialized carrier proteins such as androgen-binding protein

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11
Q

describe amino acids and arachidonic acid

A

:the catecholamines (norepinephrine and epinephrine), prostaglandins, prostacyclin’s, and leukotrienes. Also included are the thyroid hormones

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12
Q

how do hormones interact?

A

through specific hormone receptors
1. cell-surface receptor
2. intracellular receptors

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13
Q

explain cell-surface receptors

A

interact with peptide hormones or catecholamines. Activation of these receptors generates large quantities of small intracellular molecules called second messengers. Examples include cAMP, cGMP 1,2-diacylglycerol (DAG), inositol 1,4,5-triphosphate (IP3), and Ca2+.

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14
Q

explain intracellular receptors

A

are used by steroid hormones, thyroid hormones, and vitamins A and D. Steroid hormones and vitamins A and D can easily penetrate both plasma and nuclear membranes.

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15
Q

hormone production is often controlled thoguh feedback mechanisms, explain them

A

*Negative feedback occurs when the response diminishes the original stimulus bc there is excess.

*Positive feedback, which occurs when the response enhances the original stimulus to produce more.

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16
Q

explain the general mechanism of protein hormone actions

A

Protein hormones bind to cell surface receptors and initiate a cascade of intracellular signaling reactions that may include G-protein and various protein kinases resulting in the synthesis of second-messenger molecules. These molecules, may influence channel proteins, nuclear transcription, and protein synthesis or degradation.

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17
Q

explain the general mechanism of steroid hormone actions

A

Steroid hormones, which include nuclear-initiated steroid signaling and membrane-initiated steroid signaling. In the nuclear-initiated steroid signaling (green arrows), some steroid hormones (e.g., glucocorticoids, androgens) cross the plasma membrane and bind to specific cytoplasmic receptors. This complex travels to the nucleus and regulates the transcription of specific genes. Other steroid hormones (e.g., estrogens, progestogens) bind to their specific receptors directly in the nucleus (blue arrows). In membrane-initiated steroid signaling (red arrows), the steroid receptors are expressed on the cell membrane, usually in the caveolae.

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18
Q

where does the hypophysis (pituitary gland) lies and where does it come from?

A

Lies in the cavity of sphenoid bone (sellaturcica). It is composed of glandular epithelial tissue (origin of adenohypophysis) and neural tissue axon’s terminals (origin of neurohypophysis pars nervosa).

Develops from oral ectoderm (Rathke’s pouch) and nerve tissue (an evagination of the floor of the diencephalon)

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19
Q

describe adenohypophysis and its parts

A

Cords or clusters of epithelioid cells, separated by abundant sinusoidal capillaries (fenestrated)

  1. Pars distalis: major secretory portion (diff types of cells)
  2. Pars tuberalis
  3. Pars intermedia: rudimentary in humans; colloid cysts
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20
Q

describe neurohypophysis (pars nervosa) and its parts

A

Developmentally is part of hypothalamus

  1. Pars nervosa:neurosecretory axons and their endings with glial cells
  2. Infundibulum or Neural stalk:neurosecretory axons forming hypothalamohypophyseal tracts
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21
Q

explain the development of the pituitary gland

A

a. The pituitary gland develops from two different structures: an ectodermal diverticulum of the roof of the oropharynx (Rathke’s pouch) and a downward extension of the neuroectoderm at the floor of diencephalon. This drawing shows the relationship between these two structures in a 6-week-old embryo.
b. The pituitary gland at 10 weeks in development shows ectodermal tissue from the oropharynx in close proximity to neural tissue. The Rathke’s pouch is about to lose connection with the oropharynx.
c. Cells from Rathke’s pouch divide and differentiate rapidly into the pars distalis and encircle the infundibulum, which with pars nervosa forms the neuroectodermally derived posterior lobe of the pituitary gland.

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22
Q

the master organs?

A

pituitary gland and th ehypothalamus

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23
Q

identify

A

Pituitary gland and the hypothalamus

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24
Q

what does the superior hypophyseal artery supply?

A

supplies the pars tuberalis, median eminence, and infundibulum of the hypothalamus, where it gives rise to a capillary network that drains into the hypophyseal portal veins. These veins give rise to a second capillary network in the pars distalis, where the neuroendocrine secretions produced in the hypothalamus are released.

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25
Q

what does the inferior hypophyseal artery supply?

A

provides the blood supply to the pars nervosa. The blood from the pituitary gland drains into the cavernous sinus and leaves the cranial cavity via the internal jugular veins.

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26
Q

which are the cell types in the adenohypophysis?

A
  1. Chromophobes
  2. Chromophils: Acidophils (most abundant) and Basophils
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27
Q

which are the types of acidophils?

A

somatotropes and lactotropes (Mammotropes)

28
Q

describe somatotropes

A

Secrete growth hormone (somatotropin). Secretion is regulated by two hypothalamic hormones growth hormone-releasing hormone (GHRH) and inhibited by somatostatin.Recently a peptide called ghrelinhas been described as a stimulator of GH secretion.

Tumors -→gigantism(children), acromegaly (adults)

29
Q

describe lactotropes or mammotropes

A

Secrete prolactin. Stimulates growth of mammary gland during 2nd half of pregnancy and milk secretion after birth. Secretion inhibited by dopaminefrom hypothalamus. Thyrotropin-releasing hormone (TRH) and vasoactive inhibitory peptide (VIP) also stimulate secretion and production. Pregnancy and lactation causes hypertrophy and hyperplasia of these cells.

30
Q

identify

A

adenohypophysis derivadas de proteina
erytocytes - gold
cherry color - acidophilos
violeta - basophilos

31
Q

identify

A

adenohypophysis derivados de proteina, almacenadas en granulos secretorios esperando señal para ser liberadas

32
Q

which aare the types of basophils?

A

Thyrotropes (PAS-positive)
Gonadotropes (PAS-positive)
Corticotropes

33
Q

descrobe thyrotropes?

A

Secrete TSH = thyrotropin, stimulates hormone secretion by thyroid gland. Controlled by Thyrotropin-releasing hormone (TRH) produced in hypothalamus. Secretion is inhibited by negative feedback mechanism from thyroid hormones

34
Q

describe gonadotropes

A

Secrete two hormones that stimulate gonads of both males and females. Regulated by gonadotropin releasing hormone (GnRH) produced by the hypothalamus. Both gonadotropins also are regulated by negative feedback from hormones secreted by gonads.

*Follicle stimulating hormone (FSH)
Stimulates ovarian follicles and testicular seminiferous tubules

*Luteinizing hormone (LH)
promotes ovarian follicle maturation and progesterone secretion in women and stimulates interstitial cells of testes.

35
Q

describe corticotropes

A

Precursor molecule is proopiomelanocortin (POMC), cleaved Secrete Adrenocorticotropic hormone (ACTH) Stimulates secretion of glucocorticoids by adrenal cortex. Regulated by corticotropin-releasing hormone (CRH) produced by hypothalamus.

36
Q

identify

A

Pars Distalis of Adenohypophysis

erytroctes - gold
cherry - acidophils
purple - basophilsgos purple with white lumen

37
Q

describe chromophobes in adenohypophysis

A

Poorly stained, when examined in EM two populations. One with secretory granules the other none. Some chromophobes may also represent stem cells that have not yet differentiated.

The best way to identify chromophils is by immunocytochemistry with specific antibodies against the products (hormones)

38
Q

describe folliculostellate cells in adenohypophysis

A

are the supporting cells. Abundant gap junctions (connexin-43 protein). These cell transmits signals from the pars tuberalisto pars distalis. Discovery of gap junctions interconnecting folliculostellatecells with hormone-producing cells support the idea that these cells coordinate and modulate hormone release throughout the anterior lobe of the pituitary gland.

39
Q

the control of the pars distalis is due to?

A

–Hypothalamic releasing hormones (capillary plexus)
–Hypothalamic inhibiting hormones.

40
Q

identify

A

pars distalis of adenohypophyssis

41
Q

identify

A

acidophils and basophils in pars distalis of adenohypophyssis

42
Q

identify

A

Pars Distalis of Adenohypophysis; acidophils and basophils in pars distalis of adenohypophyssis

43
Q

what si the pars tuberalis?

A

Region surrounding the infundibulum and neurohypophysis. Most cells secrete gonadotropins (FSH and LH not high concentrations)

44
Q

what is pars intermedia

A

Made of cords of cells (one cell width) and follicles. Melanocyte-stimulating hormones (MSH),is found in the human pars intermedia in small amounts, the basophils of the pars intermedia are assumed to be corticotropes

45
Q

tumors in the hypophysis ?

A

are usually benign, can produce ACTH, TSH, prolactin, growth hormone etc.

46
Q

identify

A

pars intermedia with coloide (violet) and axons of neurohypophysis on right

47
Q

identify

A

neurohypophysis, aapriencia de tejido nervioso

48
Q

identify

A

Neurohypophysis —Adenohypophysis

coloide violeta, pars intermedia

49
Q

whwre are oxytocin and ADH produced?

A

Immunocytochemical studies indicate that oxytocin and ADH are produced by separate sets of neurons within the supraoptic and paraventricular nuclei of the hypothalamus. por transporte axonico se amacenan en pars nervosa para liberar sustancias. synthesized in different neurons. Biochemical studies have demonstrated that the supraoptic nucleus contains equal amounts of both hormones, whereas the paraventricular nucleus contains more oxytocin than ADH, but less than the amount found in the supraoptic nucleus.

50
Q

what is the neurohypophysis?

A

(the posterior lobe) of the pituitary gland is an extension of the central nervous system (CNS) that stores and releases secretory products from the hypothalamus.

51
Q

describe pars nervosa components

A

Composed of unmyelinated axons of secretory neurons located in the supraopticand paraventricularnuclei. Have herring bodies with oxytocin and ADH and contain secrretory granules and are released and enter fenestrated capillaries.

52
Q

which cells acompany th epars nervosa?

A

pituicytes: cells of the neurohypophysis, highly branched glial cells. GFAP+. similar funcitons to astrocytes.

53
Q

which hormones are present in the pars nervosa?

A

Two hormones (Secreted by different cells)
*Vasopressin = Antidiuretic hormone (ADH)
*Oxytocin
*Each vesicle also contains ATP and neurophysin

54
Q

identify

A

pituicytes in neurohypophysis

55
Q

identify

A

Herring bodies

56
Q

identify

A

coloide, pars nervosa

57
Q

identify

A

secretory granuels of herring bodies with vesicles, vasopresin and oxytocin para endothelium fenestrated con doiafragma para el capillar

58
Q

describe function of ADH vasopresin

A

Secretion triggered by changes in plasma osmolality, detected by the carotid bodies and cell bodies of hypothalamic secretory neurons (osmoreceptors). ADH promotes insertion of water channels (aquaporins) into distal convoluted tubules and collecting ducts.

*Pain, trauma, emotional stress, nicotine affects ADH secretion. Diabetes insipidus

59
Q

describe oxytocin function

A

Promotes contraction of uterine smooth muscle and myoepithelial cells of mammary gland. Secretion triggered by neural stimuli that reach the hypothalamus
*In the uterus distension of cervix initiates the reflex
*In the breast effect on myoepithelial cells. Suckling initiates the sensory reflex.

60
Q

where is the pineal gland or epiphysis cerebri?

A

Found posterior wall of third ventricle, above roof of diencephalon. Covered by the pia mater, made of cellular cords and follicles.

*The pineal gland is a photosensitive organ and an important regulator of the circadian rhythm. It obtains information about light and dark cycles from the retina via the retinohypothalamictract, which connects in the suprachiasmatic nucleus with sympathetic neural tracts traveling into the pineal gland.

61
Q

which cells are produced by pineal gland and describe melatonin production

A

Pinealocytes: Hormone is Melatonin

Interstitial (glial) cells: staining and ultrastructural features that closely resemble those of astrocytes

During the day, light impulses inhibit the production melatonin. It is released during the darkness. Involved in circadian and seasonal biorhythms. Secretion responds to variations in light intensity.

Recent studies suggests a role in adjusting to changes in day length (“jet lag”) and seasonal affective disorder (SAD)

Unmyelinated axons innervate the pinealocytes. Norepinephrine, serotonin, dopamine, histamine and somatostatin have been detected.

Tumors that destroy the pineal gland are associated with precocious (early-onset) puberty

62
Q

idenitfy

A

infact pineal gland

63
Q

identify

A

human pineal gland (H&E). Pinealocytes or interstisial glial.

corpora arenasia

64
Q

What is corpora arenacea?

A

brain sand; These concretions appear to be derived from precipitation of calcium phosphates and carbonates on carrier proteins.
The concretions are recognizable in childhood and increase in number with age.
They are opaque to X-rays and located in the midline of the brain, they serve as markers in radiographic and computed tomography (CT) studies.

65
Q

idenitfy

A

Pineal Gland—Corpora arenacea (Brain sand)

66
Q

identify

A

Pineal Gland—Corpora arenacea (Brain sand)

Histo second semester 23-24 (19 decks)

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