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PHYSIOLOGY ENDOCRINE > HORMONES > Flashcards

HORMONES Flashcards

1
Q

Classifications of Hormones

A

Hormones can be classified by various means, including by their structure and function.

Traditionally there are three classifications of hormones:

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2
Q

Classical Hormones:

A

secreted from endocrine cells directly into interstitial fluid. These diffuse into the bloodstream to be distributed to all parts of the body served by the circulatory system.

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3
Q

Neurohormones:

A

synthesized in neuroendocrine cells and secreted from nerve terminals. These diffuse into blood vessels for transportation around the body.

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4
Q

Local Hormones:

A

these are secreted into the interstitial fluid and act locally, on neighbouring cells (paracrine action) or on the cell which secreted them (autocrine action).

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5
Q

Additionally, hormones can be classified by their structure:

Amino Acid Derivatives:

A

these are derived from the amino acid Tyrosine. Examples include Catecholamines and Thyroid Hormones.

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6
Q

Additionally, hormones can be classified by their structure:

Fatty Acid Compounds:

A

these are derived from a polyunsaturated fatty acid pre-cursor, usually arachidonic acid. Hormones with this structure form the group Eicosenoids, and are important in inflammatory processes.

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7
Q

Additionally, hormones can be classified by their structure:

Peptide Hormones:

A

these vary from small peptides to long chain proteins. They are synthesized via transcription and translation pathways within cells, and may be derived from prohormones. They are secreted out of the endocrine cell by exocytosis. Examples include Insulin.

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8
Q

Additionally, hormones can be classified by their structure:

Steroid Hormones:

A

these lipid soluble hormones are derived from cholesterol. They are synthesised and secreted as needed; there is no capacity for storage. Examples include Cortisol, Androgens and Calcitriol.

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9
Q

Hormone Transport

Free Hormones

A

Hormones which are not bound in the blood can be defined as ‘active’ and are able to bind to the target cell to initiate a response.

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10
Q

Hormone Transport

Water Soluble Hormones

A

Water soluble hormones are freely transported within the blood. In order to enter a cell they must bind to a membrane receptor as they cannot diffuse through the lipid bilayer.

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11
Q

Hormone Transport

Lipid Soluble Hormones

A

Lipid soluble hormones require a binding protein, usually of a polar nature in order to be transported within the bloodstream. They can freely diffuse through the target cell membranes in order to initiate a response.

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12
Q

Hormone Binding Proteins

A

Binding proteins, or globulins, are transporters of lipid soluble hormones. They can be specific to a particular hormone, or non specific, having the ability to carry many types of hormone.

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13
Q

Examples of Hormone Binding Proteins: Specific:

A

Cortisol Binding Protein
Vitamin D Binding Globulin
Thyroid Binding Globulin (carries T3 and T4)

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14
Q

Examples of Hormone Binding Proteins: Non Specific:

A

Albumin (carries all types of steroids)
Prealbumin (carries T3 and T4)
Transport proteins are synthesised and degraded within the liver.

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15
Q

Hormone Binding Protein Functions

Hormone ‘reservoir’

A
  • an equilibrium exists between the concentration of free hormone and the concentration of bound hormone. As free hormones bind to their receptors, the binding proteins release some of their load to maintain the plasma concentration of the free hormone.
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16
Q

Hormone Binding Protein Functions

A

Hormone level ‘buffer’ - Normal function involves use of only 50% of the binding capacity of hormone binding proteins. Thus they have the capacity to absorb short term peaks and troughs in synthesis of the hormone which they can carry.

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17
Q

Hormone Binding Protein Functions

Reduce hormone loss

A
  • hormones bound to a protein cannot cross the glomerulus of the kidney, thus cannot be excreted in the same way as free hormones.
    These functions result in a maintained concentration of free hormones within the bloodstream.
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18
Q

Hormone Kinetics

Plasma concentration of hormones in the blood is a net result of:

A

Rate of secretion into the blood
Rate of removal (elimination) from the blood
Elimination mechanisms include:

Enzymatic degradation
Within target cells after receptor binding
Via the liver and kidneys.

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19
Q

Factors affecting Hormone Response:

Variation by Tissue

A
  • Different tissues vary in their response to a particular hormone.
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20
Q

Factors affecting Hormone Response:

Variation by time

A
  • the initial response to a hormone may differ to the delayed response. This depends on the animal’s age, species, and by the hormone involved.
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21
Q

Factors affecting Hormone Response:

Variation by dose

A
  • Hormone levels outside the normal physiological range may elicit different responses to those within the normal range.
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22
Q

Factors affecting Hormone Response:

Status of target tissue

A
  • With overstimulation, target tissues hypertrophy, leading to increased functional tissue and an exaggerated response. Understimulation of target tissues leads to atrophy, resulting in less functional tissue and an inadequate response.
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23
Q

Chemical Structure of Hormones

Hypophysiotropic hormones

A

The chemical structure of TRH (Thyrotropin Releasing Hormone), GnRH (Gonadotropin Releasing Hormone), Somatostatin and Dopamine, which are secreted by the hypothalamus, is similar in all mammals.

On the contrary, CRH (Corticotropin Releasing Hormone) and GHRH (Growth Hormone Releasing Hormone), vary in their amino acid sequence from mammal to mammal.

TRH is a tripeptide, GnRH is a decapeptide and dopamine is a catecholamine. CRH and GHRH have 41 and 44 amino acids respectively.

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24
Q

Endocrine System

A

-Regulates and controls many metabolic processes.
-composed of endocrine glands located throughout the body that synthesize and secrete hormones.
-Lack ducts and hormones are released into the blood and transported throughout the body.
-Helps maintain body homeostasis
>ex. maintaining blood glucose levels during erratic food intake.
-Serves as one of the two major control systems of the body. (The Nervous System is faster, while the endocrine is slower)

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25
Q

Target Cells

A

-Cells with a specific receptor for a hormone.
-bind to hormone.
>initiates or inhibits selective cell activities.

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26
Q

Nervous System

A
  • Communication Method: nerve signal causes neurotransmitter release from a neuron into a synaptic cleft.
  • Target of Stimulation: other neurons, muscle cells and gland cells
  • Response Time: rapid reaction time milli secs- secs
  • Effect of Stimulation: causes stimulation (or inhibition) of another neuron, contraction (or relaxation) of muscles, or change in secretion from glands.
  • Range of Effect: typically haas localized, specific effects in the body.
  • Duration of Response: short term; milliseconds; terminates with removal of stimulus.
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27
Q

Endocrine System Features

A
  • Communication Method: secretes hormones into blood; travel within the blood and distributed to target cells throughout body.
  • Target of Stimulation: any cell in the body with a receptor for the hormone
  • Response Time: relatively slow reaction time; seconds to minutes to hours.
  • Effect of stimulation: causes metabolic activity changes in target cells.
  • Range of effect: typically has widespread effects throughout the body.
  • Duration of Response: long lasting; minutes to days to weeks; may continue after stimulus is removed.
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28
Q

Features in Common with Nervous System

A
  • Both release chemical substances, Ligands.
  • Bind to cellular receptor on particular target cells.
  • initiates cellular change in target cells.
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29
Q

Features Different from Nervous System

A
  • Hormones transported within blood to target cells.
  • Causes metabolic changes in target cells
  • Target any cells with receptors
  • Exhibit longer reaction times
  • More widespread effects through the body
  • Longer lasting effects
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30
Q

Functions of Endocrine System

A
  • Homeostasis
  • Reproduction
  • Regulating development, growth and metabolism
  • Controlling digestive Processes
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31
Q

Functions of Endocrine System (Homeostasis)

A
  • maintaining homeostasis of blood composition and volume.
  • Regulate amount of substances dissolved in blood.(ex. glucose, cations, anions)
  • Regulate blood volume, Cellular concentration, and platelet number
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32
Q

Functions of Endocrine System (Reproduction)

A
  • affect development and function

- affects expression of sexual behaviors

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33
Q

Functions of Endocrine System (Development, Growth, Metabolism)

A
  • Regulates development, growth, and metabolism
  • Regulatory roles in embryonic cell division and differentiation
  • Involved in catabolism and anabolism of proteins, carbohydrates, and lipids.
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34
Q

Functions of Endocrine System (Digestion)

A
  • Influence secretory processes.

- Influence movement through digestive tract.

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35
Q

Endocrine Gland Composition -

A

Secretory Endocrine Cells.

  • Derived from epithelium with connective tissue framework
  • Have extensive blood supply (facilitates rapid uptake of hormones)
  • Two organizations: (a.) Single organ with endocrine function.
    (b. ) Cells in small clusters in organs with another function.
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36
Q 
Endocrine Organs (Single Organ) 
-Single organs that are entirely endocrine in function:
A 
>Pituitary Gland
>Pineal Gland
>Thyroid Gland
>Parathyroid Glands
>Adrenal Glands
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37
Q

Pituitary Gland

-POSTERIOR PITUITARY:

A

> Hormones Produced and Function:
=Oxytocin (OT);Uterine contractions; breast milk release.
=Antidiuretic Hormone (ADH); Fluid Balance

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38
Q

Pituitary Gland

-ANTERIOR PITUITARY:

A

> Hormones Produced and Function:

=Thyroid-Stimulating Hormone (TSH); Stimulates thyroid gland to release thyroid hormone.

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39
Q

Prolactin (PRL);

A

Breast Milk production.

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40
Q

Follicle-stimulating hormone (FSH);

A

Development of gametes (and follicle in female)

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41
Q

Luteinizing Hormone (LH);

A

Development of gametes (and ovulation in female)

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42
Q

Adrenocorticotropic Hormone (ACTH);

A

Stimulates adrenal cortex to release corticosteroids.

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43
Q

Growth Hormone (GH)

A

Stimulates cell growth and division. Affects most body cells, especially muscular and skeletal system. stimulates liver to release insulin like growth factor 1 and 2.

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44
Q

Pineal Glands Hormones Produced and Function;

A

Melatonin; makes us drowsy. helps regulate the body’s circadian rhythm with increased levels at night.
*responsible for synthesis of two hormones of anterior pituitary gland; involved in regulation of reproductive system.

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45
Q

Parathyroid Glands >Parathyroid Hormone (PTH)

A

Increases blood calcium levels.

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46
Q

Adrenal Glands:

-ADRENAL MEDULLA

> Hormones produced and Function:

A

=Catecholamines (Epinephrine and norepinephrine); Prolong fight-or-flight response.

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47
Q

Adrenal Glands:

-ADRENAL CORTEX

> Hormones produced and Function:

A

=Mineralcorticoids (ex. aldosterone); regulate blood sodium and potassium levels.

=Glucocorticoids (ex. cortisol); Participate in stress response.

=Gonadocorticoids (ex. androgens); stimulates maturation and functioning of reproductive system.

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48
Q

Endocrine Cells Within Other Organs -Housed in tissue clusters in specific organs

-Secrete one or more hormones. (Organ with additional primary function)

A 
-Includes: 
>Hypothalamus, Thymus, Skin. 
>Heart, Liver, Stomach. 
>Pancreas, Small intestine. 
>Kidneys, Gonads.
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49
Q

Skin Hormones Produced and Function:

A

-Viatmin D (later converted to calcitriol through enzymes in liver and kidney); promotes absorption of calcium from gastrointestinal tract into blood.

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50
Q

Hypothalamus -Function

A

Regulates hormone release from pituitary gland.

  • controls and influences many endocrine functions.
  • Has indirect control over hormone release from; thyroid and adrenal glands. liver testes and ovaries.
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51
Q

Thymus Hormones produced and function:

A

-Thymosin, Thyulin, Thymopoietin; Stimulates maturation of T-lymphocytes.

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52
Q

Heart -

A

Atrial Natriuretic peptide (ANP); regulates blood sodium levels and blood volume.

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53
Q

Stomach -

A

Gastrin; increases secretions and motility of the stomach.

54
Q

Liver -kidney

A

Angiotensinogen; Regulates blood volume and blood pressure.

-Erythropoietin (EPO), Increases/stimulate production of erythrocytes.(liver)

55
Q

Pancreas -

A

Insulin; Decreases blood glucose

-Glucagon; increases blood glucose

56
Q

Small intestine -

A

Secretin & Cholecystokinin; regulates digestive processes of the small intestine.

57
Q

Kidneys -

A

Erythropoietin (EPO); increases production of erythrocytes.

58
Q

Testes (Gonads)

A

-Androgens (testosterone), inhibin; stimulate maturation and function of male reproductive system.

59
Q

Ovaries (Gonads)

A

-Estrogen, progesterone, inhibin; stimulate maturation and function of female reproductive system.

60
Q

Endocrine Reflexes

A
  • Regulated secretion of hormone controlled through reflex.
  • Pre-programmed response to certain stimuli.
  • Initiated by one of three types of stimulation:
61
Q

Three Types of Stimulation

A
  • Hormonal Stimulation
  • Humoral Stimulation
  • Nervous System Stimulation
62
Q

Hormonal Stimulation

A
  • Release of a hormone in response to another hormone.
    ex. Anterior pituitary releases thyroid-stimulating hormone (TSH). TSH stimulates thyroid gland to release thyroid hormone (TH).
63
Q

Humoral Stimulation

A

n -Release of a hormone in response to changes in level of nutrient or ion in the blood. (Responds to local environment)

  • Act on target cells to offset further loss or eliminate excess.
    ex. Blood glucose levels increase. Increased blood glucose stimulates pancreas to release insulin.
64
Q

Nervous System Stimulation

A
  • Release of a hormone in response to stimulation by the nervous system.
    ex. Sympathetic nervous system increases in activity. Sympathetic preganglionic axons stimulate adrenal medulla to release epinephrine and noreepinephrine.
65
Q

Three Structural Categories of Circulating Hormones

A
  • Steroid Hormone
  • Protein Hormone
  • Biogenic Amine
66
Q

Steroid Hormone

A
  • Lipid soluble molecules synthesized from cholesterol.
  • includes steroids produced in gonads
  • includes steroids synthesized by adrenal cortex
  • Calcitriol (calcium regulation) sometimes classified in this group
  • Lipid soluble sticks around longer than water soluble.
67
Q

Protein Hormone

A
  • Water soluble; most hormones are in this category.
  • Composed of small chains of amino acids.
  • Includes polypeptides; between 14 to 199 amino acids. (insulin, glucagon, PTH)
  • Includes Oligopeptides; between 3 to 10 amino acids. (Oxytocin, ADH)
  • Includes glycoproteins; composed of proteins with attached carbohydrate. (FSH, TSH)
68
Q

Biogenic Amine

A
  • Modified amino acids
  • Includes; Catecholines=released from adrenal medulla. Thyroid hormone released from thyroid gland

-Water soluble; exception of thyroid hormone. Contains two tyrosine amino acids containing a nonpolar ring.

69
Q

Local Hormones

A
  • Large group of signaling molecules
  • Do not circulate within the blood.
  • Bind with Same cell or neighboring cells; (sometimes not classified as hormones).
70
Q

Eicosanoids

A
  • A primary type of local hormones.
  • Formed from fatty acids containing chain of 20 carbon atoms
  • Derived from phospholipids within cells plasma membranes.
71
Q

Eicosanoid Functions

A
  • Play a role in inflammation as part of the body’s defenses.
  • Initiate smooth muscle contraction.
  • Stimulate pain receptors.
  • Other local signaling functions.
72
Q

Transport of Water-Soluble Hormones

A
  • Chemical interactions between the water-soluble hormone and the fluid of the blood (blood plasma) permit the hormone molecule to readily dissolve.
  • Are easily transported in aqueous environment
    (ex. Parathyroid hormone)
73
Q

Transport of Lipid-Soluble Hormones -

A

Do not readily dissolve within the aqueous environment of the blood.
-Require carrier molecules; water soluble proteins synthesized by the liver. “Ferry” the hormone molecules within the blood.
-Binding between hormone and protein is only temporary. (may detach and reattach)
>Bound Hormone: attached to carrier
>Unbound (free) Hormone: not attached
*Only unbound hormone are able to exit blood and bind target organs
=Other Transporter Functions:
-Protects hormones and prevents destruction.
-why some water-soluble hormones are transported by carrier proteins

74
Q

Transport of Lipid-Soluble Hormones

A

-Do not readily dissolve within the aqueous environment of the blood.
-Require carrier molecules; water soluble proteins synthesized by the liver. “Ferry” the hormone molecules within the blood.
-Binding between hormone and protein is only temporary. (may detach and reattach)
>Bound Hormone: attached to carrier
>Unbound (free) Hormone: not attached
*Only unbound hormone are able to exit blood and bind target organs
=Other Transporter Functions:
-Protects hormones and prevents destruction.
-why some water-soluble hormones are transported by carrier proteins

75
Q

Lipid-Soluble Hormone Interactions

A
  • Relatively small, non-polar molecules. lipophilic (lipid loving)
  • Able to diffuse across the plasma membrane.
  • Bind to intracellular receptors in cytosol or nucleus. (form hormone receptor complex)
  • Results in synthesis of new protein.
76
Q

Water-Soluble Hormone Interactions

A
  • Polar molecules unable to cross plasma membrane.
  • initiate series of biochemical events, signal transduction pathway. Initiated by the hormone which is the signaling molecule, or First Messenger.
  • Results in formation of second molecule; Termed Second Messenger (ex. cAMP). Modifies some cellular activity.
77
Q

Multiple Results possible from hormone activation (ex. activation or inhibition of enzymatic pathways)

A
  • Stimulation of growth through cellular reproduction.
  • Stimulation of cellular secretions.
  • Changes in membrane permeability
  • Muscle contraction or relaxation.
  • Result dependent on hormone, messenger types and enzymes phosphorylated.
78
Q

Up-regulation

A

cells may increase the number of receptors, thereby increasing cell sensitivity to a hormone through the process of up-regulation.

79
Q

Down-regulation

A

cell may decrease its number of receptors and reduce the cells sensitivity to a hormone through down regulation.

80
Q

Hormone Interaction Types (target cell binding different hormones)

A
  • Synergistic
  • Permissive
  • Antagonistic
81
Q

Synergistic Interactions

A
  • Work together
  • Activity of one hormone reinforcing activity of another hormone. (ex. female reproductive structures; more influenced by both estrogen and progesterone than either alone.)
82
Q

Permissive Interactions

A

-Activity of one hormone requiring a second hormone.

oxytocin required for milk ejection. Requires prolactin release to produce breast milk.

83
Q

Antagonistic Interactions

A

-Activity of one hormone opposing the affects of another hormone. (ex. Glucagon increasing blood glucose levels and insulin decreasing blood glucose levels.)

84
Q

Pineal Gland

A

-Small structure forming posterior region of epithalamus.

85
Q 
Hypothalamus and (Posterior) Pituitary Gland
 -Hormones stored in posterior pituitary.
A
  • Synthesized in hypothalamus by neurosecretory cells. Packed within secretory vesicles, transported by fast axonal transport. released from synaptic knobs of neurons.
  • Oxytocin; Produced by Paraventricular nucleus.
  • Antidiuretic Hormone; Produced by Supraoptic nucleus.
  • Nerve signal sent from hypothalamus, travels along the hypothalamo-hypophyseal. Hormones are then released into bloodstream by posterior pituitary gland.
86
Q 
Hypothalamus and (Anterior) Pituitary Gland -
Hormone release from anterior pituitary.
A

Specific hormones released from hypothalamus. Travel through the primary plexus (hypothalamus) to secondary plexus (anterior pituitary) by way of the hypophyseal portal veins.

  • Hormones released from anterior pituitary. Reach target cells through bloodstream.
  • Hypothalamo-hypophyseal portal system
87
Q

Hormones of hypothalamus that control release of hormones from the anterior pituitary -Regulatory Hormones

A

(a) Releasing Hormones
(b) Inhibiting Hormones
- Thyrotropin-releasing Hormone (TRH)
- Prolactin-Releasing Hormone (PRH)
- Gonadotropin-releasing hormone (GnRH)
- Corticotropin-releasing Hormone (CRH)
- Growth Hormone-releasing Hormone (GHRH)

88
Q

Regulatory Hormones Secreted into the blood to regulate anterior pituitary hormones.

A

Fall into two groups; Releasing and Inhibiting hormones.

  • Releasing Hormones- Stimulate secretion of specific anterior pituitary hormones.
  • Inhibiting Hormones- Deter secretion of specific anterior pituitary hormones.
89
Q

Thyrotropin-Releasing Hormone (TRH)

A

Increases secretion of Thyroid Stimulating Hormone (TSH)

90
Q

Prolactin-Releasing Hormone (PRH)

A

Increases secretion of prolactin (PRL)

91
Q

Gonadotropin-Releasing Hormone (GnRH)

A

Increases secretion of follicle-stimulating hormone (FSH) and Luteinizing Hormone (LH)

92
Q

Corticotropin-Releasing Hormone

A

Increases secretion of adrenocorticotropic hormone. (ACTH)

93
Q

Growth hormone-Releasing hormone (GHRH)

A

Increases secretion of growth hormone (GH)

94
Q

Melanocyte-Stimulating Hormone

A

-Anterior Pituitary also releases melanocyte-stimulating hormone (MSH) which stimulates the rate of melanin synthesis by melanocytes in the integument and the distribution of melanocytes in the skin. Usually ceases prior to adulthood, except in certain diseases.

95
Q

Representative Hormones Regulated by the Hypothalamus; Growth Hormone Functions include:

A

-stimulation of linear growth at epiphyseal plate
-hypertrophy of muscle
-many other physiologic changes.
>Release controlled by GHRH influenced by:
-Age, time of day, and nutrient levels.
-Stress and exercise.

96
Q

Growth Hormone Targets >Hepatocytes (liver):

A
  • Release insulin-like growth factor. (IGF)
  • overlapping function with GH
  • Responsible for greater response.
  • stimulated to increase glycogenolysis and gluconeogenesis; increases blood glucose levels (rise reffered to as diabetogenic)
  • All cells with IGF or GH receptors
  • Bone and muscle particularly affected; activates second messengers. increases protein synthesis. increases mitosis; cell differentiation.
  • in muscle increased uptake of amino acids.
  • Adipose Tissue-stimulated to increase lipolysis and decreased lipogenesis. Thus increases levels of glycerol and fatty acids in blood. with glucose, provide molecules necessary for generating ATP.
97
Q

Growth Hormone Target Feedback

A
  • With increased levels of GH or IGF
  • hypothalamus stimulated to release growth hormone-inhibiting hormone.
  • inhibits release of GH from anterior pituitary
  • GH release also directly inhibited by itself.
98
Q

Pituitary Dwarfism

A
  • inadequate growth hormone production.
  • due to hypothalmic or pituitary problem.
  • short stature and low blood sugar.
99
Q

Pituitary Gigantism

A
  • Too much growth hormone
  • excessive growth and increased blood sugar
  • enormous internal organs
  • die at early age if untreated
100
Q

Acromegaly

A
  • excessive GH production in adult
  • enlargement of bones of face, hands and feet.
  • increased release of glucose
  • internal organs increased in size
  • results from loss of feedback control of growth hormone.
101
Q

Representative Hormones regulated by the hypothalamus;

A

Thyroid gland and hormone >Thyroid hormone synthesis

  • iodide ion moved by active transport into follicular cells.
  • Two I (neg) formed to form molecular Iodine
  • Thyroglobulin, a glycoprotein, synthesized in follicular cells.
  • bind together to form immature thyroid hormone
  • stored in colloid in this form
102
Q

Thyroid Hormone Release

A
  • some colloid internalized by exocytosis into follicular cell.
  • travels to lysosome
  • enzyme releases mature thyroid from precursor
  • released into bloodstream
103
Q

Thyrotropin-Releasing Hormone

A

released from hypothalamus -enters in response to decreased blood levels of thyroid hormone.
-also stimulated by; cold weather, pregnancy, high altitude and hypoglycemia.
>TRH binding to cells of the anterior pituitary
-stimulates anterior pituitary to release Thyroid-stimulating hormone (TSH)
>TSH binding to receptors of follicular cells
-stimulates release of thyroid hormone
-has two forms released into circulation; Triiodothyronine (T3) and Tetraiodothyronine (T4)
>T3 and T4 transported within blood by carrier molecules
-randomly become unbound and exit blood stream
>Thyroid hormone moved into target cells. binds intracellular receptors.
>T3 vs. T4
-Much greater amount of T4 produced
-T3 the most active from of thyroid hormone
-Most cells able to convert T4 to T3
>adjusts basal metabolic rate in many cells. stimulates synthesis of sodium potassium pumps in nervous tissue.
>action generates heat
-rise in temperature referred to calorigenic effect
>stimulates increased amino acid and glucose uptake
>Increases cellular respiration enzymes within mitochondria.
>stimulates other target cells to meet additional ATP requirements; hepatocytes stimulated to increase glycogenolysis and gluconeogenesis. decreased glycogenolysis. glucose released into blood stream.
>adipose tissue cells stimulated to increase lipolysis (break down fat); decrease lipogenesis.
>glycerol and fatty acids released into blood as alternative fuel molecules. Saves glucose for the brain.
>Increased respiration rate: to meet additional oxygen demand.
>Increased heart rate and force of contraction; increases blood flow to tissues.increased receptors for epinephrine and norepinephrine on heart.
>Increased Thyroid hormone
-Inhibits release of TRH from hypothalamus
-inhibits release of TSH from the anterior pituitary
-Causes release of growth inhibiting hormone (further inhibits release of TSH from anterior pituitary).

104
Q

Hyperthyroidism

A
  • result from excessive production of TH
  • Increased metabolic rate, weight loss, hyperactivity, and heat intolerance.
  • caused by T4 ingestion, excessive stimulation by pituitary or loss of feedback control in thyroid.
  • Treated by removing the thyroid (with daily hormone supplements)
105
Q

Hypothyroidism

A
  • Results from decreased production of TH
  • Low metabolic rate, lethargy
  • cold intolerance, weight gain, and photophobia
  • caused by decreased iodine intake, loss of pituitary stimulation of thyroid, postsurgical or immune system destruction of thyroid.
  • treated with thyroid hormone replacement.
106
Q

Goiter

A
  • Enlargement of thyroid
  • typically due to insufficient dietary iodine
  • lack of dietary iodine preventing thyroid from producing thyroid hormone.
  • once relatively common in United States; now iodine added to table salt.
107
Q

C cells of Thyroid Gland

A

-C cells of thyroid gland secrete calcitonin
>Functions of Calcitonin:
-stimulates osteoblast to use calcium to build bone (decreased blood calcium levels).
-stimulates kidneys to excrete calcium in urine (decreases blood calcium levels.
-Works opposite of PTH

108
Q

Parathyroid Gland

A

-Four nodules on posterior thyroid gland.
>Two different Cell Types:
-Chief Cells: Source of parathyroid hormone. released in response to decreased blood calcium levels. return blood calcium to normal levels.
-Oxphil Cells: unknown function

109
Q

Adrenal Medulla

A
  • forms inner core of each adrenal gland
  • red brown color due to extensive blood vessels.
  • releases epinephrine and norepinephrine with sympathetic stimulation.
110
Q

Adrenal Cortex

A
  • synthesizes more than 25 corticosteroids
  • yellow color due to lipids within cells.
  • Three regions producing different steroid hormones.
  • zona glomerulosa, zona fasciculata, zona reticularis
111
Q

Zona Glomerulosa

A
  • Thin, outer cortical layer.
  • mineralcorticoids synthesized here.
  • help regulate electrolyte concentration in body fluids.
  • Aldosterone,principal mineralcorticoid; stimulates sodium ion reabsorption (water follows) and potassium ion secretion at the kidneys.
112
Q

Zona Fasciculata

A
  • middle largest layer
  • parallel cords of lipid rich cells.
  • glucocorticoids synthesized here
  • primary ones cortisol and corticosterone
113
Q

Zona Reticularis

A
  • Innermost region of cortex
  • secrete minor amounts of sex hormones, Gonadocorticoids.
  • Primary ones, androgens, male sex hormones.
  • converted to estrogen in females
  • estrogen amount small compared to gonads
  • can result in elevated tetosterone in adrenal tumors
114
Q

Glucocorticoids

A
  • cortisol and corticosterone most common.
  • increase nutrient levels in blood
  • attempt to resist stress and repair injured tissue
115
Q

Pancreatic Islet Cells

A
  • small clusters of endocrine cells scattered among acini.
  • 1% of total pancreatic volume
  • composed of two primary cell types:
  • Alpha Cells; secreting glucagon
  • Beta Cells; secreting insulin
116
Q

Blood glucose concentration

A
  • pancreatic endocrine function; maintaining normal blood glucose.
  • Normal Range 70-110 mg of glucose/deciliter
  • chronically high levels damaging to blood vessels and kidneys.
  • low levels resulting in lethargy, mental and physical impairment and death if too low.
117
Q

Lowering High Blood Glucose levels with Insulin

A
  • Insulin released from pancreas following food intake
  • Glucose levels detected by chemoreceptors.
  • Target cells bound by insulin; activates second messenger in target cells.
118
Q

Lowering High Blood Glucose Levels with Insulin:

A

Hepatocytes >in Hepatocytes:

  • glycogenesis stimulated
  • glycogenolysis and gluconeogenesis inhibited.
  • glucose molecules removed from blood and stored as glycogen.
119
Q

Lowering HBGL with Insulin:

A

Adipose tissue -Lipogenesis stimulated and lipolysis inhibited

  • decreased fatty acid levels in blood
  • Storage of fat increased.
120
Q

Release of Insulin

A
  • results in decrease in all nutrients in the blood.
  • increase in synthesis of storage forms of molecules
  • decrease of alternative nutrients; cells more likely to use available glucose.
  • decreases with decreased blood glucose levels
121
Q

Raising Blood Glucose Levels with Glucagon

A
  • Levels detected by alpha cells in pancreas.
  • glucagon released in response to low blood glucose levels; can cause lethargy and death if they drop too low. binds plasma membrane receptors to activate second messengers.
  • Facilitates nutrient breakdown and release.
122
Q

Raising BGL with Glucagon:

A

Hepatocytes -glycogenolysis and gluconeogenesis stimulated.

  • glycogenesis inhibited.
  • glucose released into blood.
123
Q

Raising BGL with Glucagon:

A

Adipose tissue -Lipolysis; stimulated.

  • lipogenesis; inhibited.
  • Fatty acids and glycerol released from storage into blood.
124
Q

Release of Glucagon

A
  • Increases glucose; fatty acids and glycerol in blood.
  • decreases storage forms of these nutrients.
  • has no effect on protein components.
  • inhibited by increased blood glucose levels.
125
Q

Diabetes Mellitus

A
  • inadequate uptake of glucose from blood.
  • with chronically elevated glucose, blood vessels damaged
  • leading cause of retinal blindness, kidney failure and nontraumatic amputations in the United States
  • associated with increased heart disease and stroke
126
Q

Type 1 diabetes

A
  • absent or diminished release of insulin by pancreas
  • tends to occur in children and younger individuals
  • may have autoimmune component
  • requires daily injections of insulin
127
Q

Type 2 diabetes

A
  • from decreased insulin release or insulin effectiveness
  • obesity major cause in development
  • tends to occur in older individuals, but can occur in young adults
  • treatment with diet, exercise and medications
128
Q

Gestational diabetes

A
  • seen in some pregnant women
  • if untreated causes risk to fetus and increases delivery complications
  • increases chance of later developing type 2 diabetes
129
Q

Hypoglycemia

A

-Glucose levels below 60 mg/dl
>numerous causes:
*insulin overdose, prolonged exercise, alcohol use, liver or kidney disfunction.
*deficiency of glucocorticoids or growth hormone, genetics.
-Symptoms of hunger, dizziness, confusion, sweating and sleepiness
-Glucagon given if individual unconscious and unable to eat.

130
Q

Kidney

A
  • Produces erythropoietin (EPO); Hormone that stimulates red blood cell production.
  • Produces Calcitriol; synthesized from vitamin D3; hormone that promotes calcium and phosphate absorption along digestive tract.
  • Produces Renin; an enzyme that triggers activation of a hormone. Renin-angiotensin system.
131
Q

Renin

A

-Converts angiotensinogen to angiotensin I in the bloodstream.
-Angiotensin I is then converted to angiotensin II , an active hormone.
>Angiotensin II does the following to increase blood volume and pressure.
-Stimulates production of ADH and aldosterone
-Increases thirst.
-Constricts blood vessels.

PHYSIOLOGY ENDOCRINE (3 decks)

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