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Physiology > Intro to Endocrine > Flashcards

Intro to Endocrine Flashcards

1
Q

Define Hormone

A

Ductless glands

Chemical signals secreted into the blood stream that act on tissues

Regulatory subtance produced that will elicit a response on a target cell (that has a specific receptor for that substance)

  • 3 major classes
  • Steroids
  • Proteins/Peptides
  • Amino Acid Analogues & Derivatives
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2
Q

Define Endocrine

A
  • Endocrine = hormone
  • Refers to ductless glands
  • Chemical signals secreted into the bloodstream–> these act on tissues
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3
Q

Define Paracrine

A
  • Hormone acts locally and diffuses in target cells in the neighborhood
  • Elicits a response by binding to a receptor
  • Exerts an effect on the cell next to it
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4
Q

Define Autocrine

A
  • Hormone acts on the same cell that produced it
  • Self secretion & self-response
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5
Q

Functions of the Endocrine System

A
  • Maintian homeostasis (regulates bioenvironment)
  • Growth and development of many tissues
  • Bones & muscles
  • Control reproduction
    • Fertility
    • Fetal growth and development
    • nourishment of the newborn
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6
Q

How do endocrine organs work?

A
  • Secrete hormones directly into the blood from the glandar cells
  • Bind to receptors on target organ
  • Elicit a response

3 types of arrangements:

  • Discrete glands
    • sole function is endocrine activity
  • Endocrine components of other organs–> (ex. pancreas, ovary, testes)
    • Ovary- cells to make eggs and cells to produce hormones
  • Scattered cells throughout other organs (C cells in the thyroid)
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7
Q

Chemical Communication between cells in the Endocrine System

A
  • Endocrine:
    • Hormone secreted into the blood, binds to distant target cells via a receptor
      • Secreted from a cell & travels a distance
  • Paracrine:
    • Hormone acts locally and diffuses in target cells in the neighborhood
      • ellicts a response by binding to a receptor (exerts an effect on the cell next to it)
  • Autocrine:
    • Hormone acts on the same cell that produced it
      • self secretion & self-response
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8
Q

Major Classes of Hormones:

Steroid #1

A
  • Originate from a cholesterol precursor
    • Changed into different hormones via enzymes
  • Organs that secrete steroids:
    • ovaries, testis, adrenal cortex
  • Specific hormones:
    • Mineralcorticoids, glucocorticoids, and testosterone, estradiol
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9
Q

Major Classes of Hormones:

#2 Protein/Peptide Hormones

A
  • Name indicates the chemical structure
  • Made up of amino acids
  • Can have slight changes in the amino acid sequence = very different hormones
  • Organs:
    • Anterior pituitary
    • Thyroid
    • Parathyroid
    • Pancreas
  • Specific hormones: insulin, prolactin, antidiruetic hormone, oxytocin
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10
Q

Major Classes of Hormones:

#3 Amino Acid Analogs & Derivatives

A
  • Named based on structure
  • Organs:
    • Thyroid gland
    • Adrenal medulla
  • Specific Hormones:
    • Thyroxine
    • Norepinephrine
    • Epinephrine
  • Most are derivatives of tyrosine
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11
Q

Hormone Receptors:

A

Synthesized hormone released from endocrine cell that makes it

No receptor for hormone = hormone will pass without binding to target tissue

If target cell has a receptor for that hormone, then it will bind to a receptor on the target cell and elicit a response.

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12
Q

Mechanisms of Hormone Action

A

Protein Hormones:

  • Can’t just diffuse through lipid bilayer
    • Need to bind a receptor
    • 2nd messenger cascade
    • Altered cell function & multiple biological effects

Steroid Hormones:

  • Derivatives of cholesterol
  • Can diffuse through the membrane b/c fat
  • Bind to steroid receptors inside the cell
  • Complex of hormone and receptor will bind to DNA in the cell
  • Will elicit new protein production and biological effects
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13
Q

Control Mechanisms:

A
  • External stimuli
    • Will signal the endocrine action in the body so that organs will secrete certain hormones
    • Fright, cold, light
  • Internal stimuli
    • Blood sugar levels, hormonal signals from another gland
  • Feedback loops
    • Positive vs. negative
    • Long feedback loops (long distance to travel in the body)
    • Short feedback loop (close proximity)
    • Negative (turn on/turn off endocrine system)- ex. like a thermostat
  • If levels are too high–> can negatively feedback to upstream organs to shut it off
  • If levels are too low –> no negative feedback, will turn on system to produce more
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14
Q

Endocrine System Comparison

(Tissues, Hormones and their involvement)

A
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15
Q

Describe the main endocrine functions of the hypothalamus

A

Posterior Pituitary Hypothalamus Function:

  • Synthesis of hormones released from posterior pituitary
  • Oxytocin
  • ADH (Vasopressin)

Communication with Posterior Pituitary =

Hypothalamic-Hypophyseal Nerve Tract

Anterior Pituitary Hypothalamus Function:

  • Synthesis of regulating hormones that act on the anterior pituitary gland
  • Release of regulating hormones that act on the anterior pituitary gland
    • Releasing hormones (stimulating)
    • Inhibiting hormones
  • Done via feedback loops
  • Ex. T4 thyroid hormone

Hypophyseal Portal System

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16
Q

Name the hypothalamic releasing and inhibiting hormones and briefly describe them

A

Hypothalamic Releasing Hormones:

  • Corticotropin releasing hormone (CRH)
    • Acts on the adrenal cortex
    • Cortisol production
  • Gonadotropin releasing hormone (GnRH)
    • Endocrine cells of the gonads
    • Androgen production
    • Estrogen production
    • Progesterone production
  • Growth hormone releasing hormone (GHRH)
    • Acts on GH
    • Liver
    • Somatomedins
    • Nonendocrine targets = many tissues
  • Growth hormone inhibiting hormone (GHIH)
    • Acts on GH
    • Liver
    • Somatomedins
    • Nonendocrine targets = many tissues
  • Thyrotropin releasing hormone (TRH)
    • Acts on TSH
    • Thyroid gland stimulating
    • Production of thyroid hormones
    • Many tissues
  • Prolactin releasing hormone (PRH)
    • Prolacting hormone
    • Mammary Gland (nonendocrine target)
  • Dopamine or pro-lactin inhibiting hormone (PIH)
    • Only non-peptide hormone
    • Major inhibitor of prolactin
17
Q

Name the primary hormones secreted from the posterior pitutary and describe their functions.

18
Q

Describe the diseases/conditions that occur with insufficient or excess posterior pitutary hormones.

19
Q

All (except 1) of the releasing/inhibiting hormones are associated to the hypothalamus.

20
Q

Hypothalamus & Pituitary Gland

(interaction between these two is an interplay between the nervous system and the endocrine system)

A
  • Base of brain (diencephalon)
  • Lies below the 3rd ventricle at the base of the brain
  • important regulator of endocrine action

Pituitary Gland (hypophysis)

  • Endocrine gland connected to hypothalamus by infundibulum (stalk containing nerves and small blood vessels)
  • Neurons that synthesize posterior pituitary hormones are made in the hypothalamus
  • Require release signal
  • Oxcytocin and Antidiruetic hormone (ADH)
21
Q

Where are the neurons located that synthesize the hormones released from the posterior pituitary ?

A

Neurons that synthesize posterior pituitary hormones are made in the hypothalamus

22
Q

Interaction between hypothalamus and anterior pituitary

A

Hypothalamus

  • produces releasing hormones
  • secreted in capillary beds from hypothalamus
  • travel to anterior pituitary and bind to receptors there
  • Stimulate anterior pituitary hormones (all protein hormones)
23
Q

Relationship of the Hypothalamus and Anterior Pituitary

A

Form a complex unit–> transcends the boundary between neuro and endocrinology

Neuroendocrine system connected to endocrine system via portal circulation

  • Requires releasing or inhibiting hormones
  • made in the hypothalamus
  • Secreted into the capillaries
  • travel to the anterior pituitary to elicit a response
24
Q

Endocrine roles of the Hypothalamus:

A

Specific endocrine functions:

  • Synthesis and release of regulating hormones that act on the anterior pituitary
    • Releasing hormones
    • inhibiting hormones
  • Synthesis of hormones released from the posterior pituitary
    • Oxytocin
    • Antidiuretic hormone (ADH) or Vasopressin (older name)
  • Communicates with pituitary gland
    • Hypothalamic-hypophyseal nerve tract (nerves that go from hypothalamus to posterior pituitary)
    • Hypophyseal portal system (capillaries that communicate with anterior pituitary)
25
Q

Relationship of the hypothalamus with the anterior and posterior pituitary

A

Hypothalamus has neurons that make oxytocin & ADH

In reference to the posterior pituitary:

If the hypothalamus becomes activated:

  • Neurons will become activated in hypothalamus
  • Neurons will transcend into the posterior pituitary
  • Neurons in posterior pituitary become stimulated to release ADH or oxytocin
  • Then will travel to target tissues to elicit a response

In reference to the anterior pituitary:

  • Hypothalamus has neurons with releasing or inhibiting hormones
  • These get into the capillaries
  • Travel through the blood system to anterior pituitary
  • Stimulate it to release hormones
  • Hormones then go to target tissues to elicit a response
26
Q

Hypothalamus has neurons that produce _______ & _________.

A

Oxytocin and ADH

27
Q

T or F: Oxytocin & ADH will only come from the posterior pituitary.

28
Q

Hormones from the portal system or releasing hormones come from the

A

posterior pituitary

29
Q

Hypothalamic Releasing Hormones:

A
  • Corticotropin releasing hormone (CRH)
  • Gonadotropin releasing hormone (GnRH)
  • Growth hormone releasing hormone (GHRH)
  • Growth hormone inhibiting hormone (GHIH)
  • Thyrotropin releasing hormone (TRH)
  • Prolactin releasing hormone (PRH)
  • Dopamine or prolactin-inhibiting hormone (PIH)
30
Q

Hypothalamic Releasing Hormones Facts:

A
  • For most, takes a very small amount to illicit a response
  • Stored in nerve terminals in the median eminence
    • Concentration is 10-100X greater than in other places
    • Specificity of the hormones is that they act on specific receptors of specific cells
  • Most are peptide/protein hormones
    • ​3-44 AA in length
    • Longer & larger = more species variation

Dopamine is the only NON-PEPTIDE hormone–> most important inhibitor of prolactin!!!

Dopamine is an Amino Acid derivative

31
Q

Dopamine

A
  • Dopamine is the only NON-PEPTIDE hormone
  • Most important inhibitor of prolactin!!!
  • Dopamine is an Amino Acid derivative
32
Q

Corticotropin Releasing Hormone (CRH)

A
  • CRH acts on corticotrophs
    • Cells with receptor for CRH
    • In the anterior pituitary
  • Stimulates the production of ACTH
  • 41 AA protein
  • Highly conserved
  • Identical in humans and rats
33
Q

Gonadotropin Releasing Hormone (GnRH)

A
  • GnRH acts on gonadotropes
    • Cells with receptor for GnRH
    • In the anterior pituitary
  • Stimulates the production of follicle-stimulating hormone (FSH) and luteinizing hormone (LH)
  • AKA luteinizing hormone releasing hormone (LHRH)
  • 10 AA
  • Very similiar in different species
34
Q

Growth Hormone Releasing Hormone (GHRH)

&

Growth Hormone Inhibiting Hormone (GHIH)

A

GHRH:

  • Acts on somatotrophs in the anterior pituitary
  • Stimulates the production of growth hormone (GH)

GHIH:

  • Also called somatostatin
  • Acts on somatotrophs in the anterior pituitary
  • Inhibit the production of growth hormone
35
Q

Thyrotropin Releasing Hormone (TRH)

A
  • Acts on thyrotrophs of the anterior pituitary
  • Stimulates thyroid stimulating hormone (TSH)
  • 3 AA peptide
  • Isolated from 25,000 ovine hypothalami- 1 mg hormone produced
  • Nobel prize received
36
Q

Prolactin Releasing Hormone (PRH)

A
  • Stimulates anterior pituitary production of prolactin (PRL)
37
Q

Dopamine

A
  • Distinct dopamine-secreting neurons in hypothalamus
  • Dopamine enters portal vessels
    • Transported to the anterior pituitary
  • Acts on lactotrophs to INHIBIT production of prolactin by the anterior pituitary
38
Q

Principle functions of the Endocrine System:

A

Maintain homeostasis

  • optimum biochemical environment for the body

Regulate growth and development

  • Muscles, bones

Control reproduction

  • Fertility
  • Fetal growth and development
  • Nourishment of newborn

Physiology (11 decks)

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