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Y2S2 VETS2012 anatomy > L1 endocrine anatomy > Flashcards

L1 endocrine anatomy Flashcards

1
Q

endocrine glands general structure?

A

Are ductless and secrete hormones

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2
Q

Endocrine response is slower than neuro response because:

A

Hormones are released from specific cells
Hormones have to diffuse to & cross capillary wall; blood transport is slower than nerves
Relies on diffusion once hormone leaves the vascular system

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3
Q

Some chemicals serve as both neurotransmitters and hormones ?

A

E.g. Adrenaline (epinephrine) and noradrenaline (norepinephrine)
Both of these molecules are produced by the adrenal glands as well as being a neurotransmitter and are part of the sympathetic response (fight or flight)

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4
Q

‘Local’ Hormones

A

Have a local effect, i.e. only travel a short distance to effector tissue
Usually only small amounts are found in the general circulation
e.g. secretin and cholecystokinin
Includes paracrine hormones which don’t enter vasculature to reach their target organ
e.g. gastrin and epidermal growth factor

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5
Q

‘General’ hormones

A

Secreted by specific endocrine glands
Transported around the body in blood
Cause many different reactions
e.g. adrenaline (epinephrine) and noradrenaline (norepinephrine) secreted from adrenal medulla
Some hormones have general and local effects
e.g. testosterone secreted from Leydig cells
Some hormones have very set target tissues with specific receptors
e.g. ACTH from anterior pituitary causes release of adrenocortical hormones from the adrenal cortex

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6
Q

List 4 types of hormones based on chemistry

A
  1. Steroid hormones
  2. Protein hormones
  3. Tyrosine hormones
  4. Fatty acid hormones(eicosanoids)
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7
Q

Carrier molecules

A

Hormones may circulate freely or be bound to carrier molecules
Free hormones degrade quickly while bound ones last longer
Carrier molecules usually proteins

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8
Q

Steroid hormones

A

hormones that structure related to cholesterol
Cells vacuolated, lots lipid, mitochondria, SER
Cortisol, aldosterone, oestrogen, progesterone, testosterone

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9
Q

Protein hormones

A

Proteins, polypeptides, amino acid hormones
Cells dense staining with secretory granules
Lots mitochondria, RER, ribosomes
ADH, oxytocin, insulin, glucagon, parathyroid h.

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10
Q

Tyrosine hormones

A

Catecholamines ( hormones made by adrenal glands), thyroid hormones

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11
Q

Endocrine organs are classically characteristised by >

A

an endocrine organ contains tissue which releases hormone directly into the blood

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12
Q

Fatty acid hormones (eicosanoids)

A

Derived from arachadonic acid

Prostaglandins, prostacyclins, leukotrienes & thromboxanes

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13
Q

List the organs that are primarily endocrine

A

Pituitary, pineal, thyroid, parathyroid, adrenals

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14
Q

List the organs that combine endocrine Fx with other major functions

A

Testes, ovary, pancreas, placenta

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15
Q

endocrine organs which have relatively incidental endocrine Fx (diffuse endocrine system)

A
  • Kidney, Liver, thymus, heart, GI tract

- Often paracrine rather than endocrine

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16
Q

Three types of endocrine organs

A

Three types

Organs that are primarily endocrine

Combines endocrine function with other major functions

Relatively incidental endocrine function (‘diffuse endocrine system’)

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17
Q

Typical Endocrine Gland Characteristics

A

Scattered throughout body and a range of embryological origins
Secrete hormones from cells that are usually derived from epithelial cell origins
Ductless
Highly vascular
Sparse connective tissue framework

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18
Q

Different Morphology of endocrine glands (4)

A
  1. Follicular
  2. Cell masses or cords
  3. Solitary endocrine cells
  4. Neurocrine cells
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19
Q

Morphology of endocrine gland Follicular

A

Thyroid, ovary

  • -> Hormones stored in follicle lumen but reabsorbed to enter capillary network
  • -> follicular in nature but no ducts
20
Q

Morphology of endocrine glands Cell masses or cords

A

Pituitary, adrenal cortex, interstitial tissue of testis, JG cells

21
Q

Morphology of endocrine gland solitary endocrine cells

A

Enteroendocrine cells

22
Q

Morphology of endocrine glands –> neurocrine cells

A

Typical neurone cells whose products are released into the blood
hypothalamus, pineal

23
Q

Fx of hormones (4)

A

Reproduction (sex hormones)
Growth and development (TH and GH)
Maintenance of internal environment (adrenals, parathyroid)
Energy production and storage (thyroid and pancreatic hormones)

Essential for life – deficiencies or excess can occur

24
Q

Hyperadrenocorticism

A

Cushings disease

25
Q

List all the areas where endocrine tissue is found

A 
Parathyroid
Thyroid
pineal
hypothalamus
pituitary
thymus
stomach
intestine
testis
placenta
uterus
ovary
kidney
adrenal
26
Q

Endocrine organs of the head region

A
27
Q

Hypothalamus

A

At base diencephalon on floor of 3rd ventricle
Immediately above the pituitary gland
‘Master gland’ as it controls the release of many of other hormones from pituitary
Integrates endocrine & CNS
Neurosecretory neurons extend down into pituitary
Hormones are all small polypeptides

28
Q

2 routes of horse release by the hypothalamus

A
  1. Neurosecretory cells

2. Hormones released

29
Q

Neurosecretory cells pathway of the hypothalamus

A

manufacture and transport their hormones via their axons to the posterior pituitary (neurohypophysis) in neurosecretory granules
Hormones stored in disteneded ends of axons (Herring bodies) until secretion

2 hormones released:
antidiuretic hormone (ADH or vasopressin; SO nuc.)
Oxytocin (PV nuc.)

30
Q

Other neurosecretory cells in the hypothalamus

A

Other neurosecretory cells in the hypothalamus
release hormones into the hypothalamic-pituitary portal vessels that travel to the anterior pituitary (adenohypophysis)
cause release or inhibition of the trophic hormones of the anterior pituitary

31
Q

Hypothalamic hormones that use the hypothalamus-pituitary portal system include:

A

Corticotrophin releasing hormone/factor (CRH/F)
Growth hormone release-inhibiting hormone (GHRIH/ somatostatin/ somatotrophin release inhibiting factor)
Prolactin release-inhibiting hormone (PRIH or dopamine)
Thyroid releasing hormone (TRH)
Gonadotropin releasing hormone/ factor (GnRH)

32
Q

B. Pituitary (Hypophysis) –? Consists of 2 regions of different tissue type

A 
Anterior pituitary (adeno-hypohysis) composed of:
Pars distalis (P. anterior)
Pars intermedia
Pars tuberalis

Posterior pituitary (neuro-hypophysis) composed of:
Pars nervosa (P. posterior)
Infundibulum
Median eminence

33
Q

Embryology of the pituitary

A
34
Q

Diaphragm sellae =

A

horizontal fold of dura, forms roof of sella turcica

35
Q

Median eminence

Infundibulum

Sella turcica

A

Median eminence = stalk with 3rd ventricle

Infundibulum
= pituitary stalk

Sella turcica
= small depression in basisphenoid

36
Q

Hormones of the pituitary

A 
Anterior pituitary
Adrenocorticotrophic h. (ACTH)
Thyroid stimulating h. (TSH)
Gonadotrophic hh.
Follicle stimulating h. (FSH)
Luteinising h. (LH)
Growth h./ somatotrophic h. (GH/ STH)
Prolactin
α-melanocyte stimulating h. (MSH; from pars intermedia)

Posterior pituitary
Oxytocin
Antidiuretic h. (ADH)/ vasopressin

37
Q

Histology of the pituitary gland

A
38
Q

Histo - andenohypophysis

A

Cords of cells & sinusoidal capillaries

Cells classed dye affinity
Chromophils (A & B)
Active, lots secretory granules
Somatotrophs 45%
Mammotrophs 20% 
Corticotrophs 20%
Thyrotrophs 5%
Gonadotrophs 5%

Chromophobes (C)
Resting?

39
Q
A
40
Q

Hsiotology of the hypophysis (cont) –> pars Intermedia (of adenohypophysis)

A
41
Q

Histology of hypophysis Neurophyopophysis

A
42
Q

Cone of Wulzen

A

=outpocket of pars intermedia that looks more like adenohypophysis in OX

43
Q

Pineal Gland = Epiphysis

A

Small, darkly pigmented outgrowth from dorsum 3rd ventricle
Sits between cerebral hemispheres & cerebellum
Foci of calcification ‘brain sand’ in advanced age
Main hormone is melatonin

44
Q

Functions of the Pineal gland

A

Regulates diurnal and circadian rhythms
Light → retina → hypothalamus → sympathetic fibres → pineal
↑ daylight → ↓ melatonin
Melatonin secreted into blood or CSF of 3rd ventricle
Alters secretion of gonadotrophic hormones by anterior pituitary
Long day breeders e.g. horse ↑ daylight → ↓ melatonin → ↑ ovarian function
Short day breeders e.g. goat ↓ daylight → ↑melatonin → ↑ ovarian function

45
Q

Other functions of the pineal gland

A
  1. Inhibits puberty
    Antigonadotophic effects
    Relatively active prepubescent animals
  2. Regulates daily fluctuations of corticosteroids
    Circadian clock in suprachiasmic nucleus
  3. Photoreceptor in lower vertebrate
    Regulates colour change
46
Q

Histology of pineal gland

A

S – brain sand
P – pinealocytes (pineal chief cells)
N – neuroglial cells

Y2S2 VETS2012 anatomy (8 decks)

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