Exam 1 Flashcards
Chemical messengers
Neurotransmitters, endocrine hormones, neuroendocrine hormones, paracrines, autocrines, cytokines
Adrenal medulla and the pituitary gland secrete in response to
A neural stimuli
Control over the anterior pituitary
Hypothalamus
Body functions regulated by hormones
- Metabolism
- Growth and development
- H2O/ electrolyte balance
- Reproduction
- Behavior
Classes of hormones
- Protein/ polypeptides
- Steroids
- Tyrosine derivatives (biogenic amines)
Protein hormones are stored in
Secretory vesicles
Steroid hormones
Cortisol and aldosterone
Examples of tyrosine derivative hormones
Dopamine, thyroxine, norepinephrine/epinephrine
Classic endocrine glands
- Pituitary
- Thyroid
- parathyroid
- Pancreas
- Adrenals
- Gonads
- Placenta
Organs or tissue with endocrine function
- Brain
- Heart
- Liver
- GI tract
- Kidneys
- Adipose
- Thymus
Parts of brain involved with endocrine function
Hypothalamus and pineal gland
Rapid hormone secretion
Adrenal medulla secretion of norepinephrine and epinephrine
Slow hormone secretion
Pituitary and thyroid hormone secretion
Negative feedback prevents
Over-activity
Negative feedback is variable by
Secretory rate and amount of activity in the target tissue
Negative feedback regulated by
- Gene transcription and translation
- Steps in Processing hormones
- Steps in releasing stored hormones
Positive feedback is seen with
Surges of hormone
Example of positive feedback
Luteinizing hormone stimulating ovulation
Diurnal secretion
Daily or circadian secretion.
Ex: growth hormone
Seasonal or circannual secretion
The Pineal gland secretes this way.
Ex: melatonin’s effect on reproduction in seasonal breeding
Cyclic or periodic variations of secretion
Due to changes in neural activity
Transport of water soluble hormones
Dissolve in plasma, transported to target tissue, diffuse out capillaries and into interstitial fluid, then into target cells
Transport of steroid and thyroid hormones
Bind to plasma proteins and circulates in the blood. They must dissociate from the protein to diffuse across capillaries and into target tissue
Hormonal clearance
Removal of a hormone
Hormone concentration
Rate of secretion-rate of clearance
Metabolic Clearance Rate (MCR)
Rate of disappearance of hormone from plasma
Ways hormones can be cleared from plasma
- Metabolic/enzymatic degradation by tissue
- Binding with tissue
- Excretion by liver into bile
- Urinary excretion by kidneys
Locations of hormonal receptors
- in/on the surface of the cell membrane
- cell cytoplasm
- cell nucleus
Types of cellular receptors
- Ion channel-linked
- G Protein-linked
- enzyme-linked
Ca2+—Calmodulin in smooth muscle: contraction occurs when
Myosin is Phosphorylated by activated MLCK
Ca2+—calmodulin in smooth muscle: relaxation occurs when
Myosin is Dephosphorylated via myosin phosphatase
Adenylyl cyclase-cAMP active state
GTP is bound
Adenylyl cyclase-cAMP inactive state
GDP is bound
What activates adenylyl cyclase
Alpha subunit—GTP complex
Active adenylyl cyclase converts
ATP to cAMP
CAMP activates
PKA
What inactivates cAMP
Phosphodiesterase
What activates phospholipase C
Alpha q subunit—GTP complex
Activated phospholipase C catalyzes what reaction
PIP2 — DAG + IP3
IP3 causes
Release of CA2+ from ER or SR
DAG + Ca2+ activate
PKC
Purpose of 2nd messenger systems
Allows hormones that cant cross membrane to affect cell
Signal amplification
How do steroid hormones affect genes
Increase protein synthesis
Mechanism of how steroid hormones inc protein synthesis
- Bind to receptor
- Go to nucleus
- Bind to DNA — transcrip — mRNA
- MRNA goes to ribosomes to form protein
How do thyroid hormones affect genes
Increase gene transcription in nucleus
How thyroid hormone signals gene transcription
- T3/T4 bind to receptor proteins in nucleus
- after binding to intranuclear receptors they can express control for days-weeks
Concentration of hormone at the cell membrane depends on:
- Rate of secretion
- Rate of delivery via circulation
- Rate of degradation
Sensitivity of target cell depends on:
- Number of functional receptors
- Receptor affinity for hormone
- Post receptor amplification
- Abundance of available effector molecules
Magnitude of hormone responses depends on
- concentration of hormone
- sensitivity of cells
- number of target cells
Duration of hormone response
Duration of hormonal availability
Mode of production of cell response
How quickly the changes begin
How long the hormone lasts depends on
Duration, amount secreted and half-life of the hormone
Cellular response is produced by
Reversible covalent modifications and genomic changes
Examples of genomic changes
- Time it takes to make mRNA
- mRNA half-life
- time to synthesize proteins
- half-life of affected proteins
Tests that measure hormones in blood
RIA and ELISA
RIA
Measures immunologic, not biology, activity
RIA test
Correlates radioactivity to hormone concentration by creating a competition between the hormone and a radioactive labeled hormone on an antibody
ELISA
Can measure any protein depending on their specificity of antibodies or sensitivity of enzyme assays
Advantages of ELISA
- No radioactivity
- Easily automated
- Cost effective
- Accurate hormone levels
- Popular choice in clinical labs
Pituitary gland
The master gland
Anterior and Posterior parts
Lies in sella turcica (sphenoid)
Anterior Pituitary gland
Comes from Rathke’s pouch (pharygeal epithelium)
Synthesizes and releases 6 peptide hormones
Posterior pituitary gland
Outgrowth from hypothalamus
Stores and secretes 2 hormones from the hypothalamus
Pars intermedia synthesizes and secretes
Melanocytes Stimulating Hormone (MSH)
Hypothalamus controls
All pituitary secretion hormonally (AP) or neurally (PP)
Hypothalamic-Hypophysial Portal system (HHPS)
Releasing and inhibitory hormones secreted into median eminence to control anterior pituitary secretion
Hypothalamic Peptide Hormones
TRH, CRH, GHRH, GnRH, Prolactin inhibitory hormone, growth hormone inhibitory hormone, Ghrelin
Anterior Pituitary Hormones
- Growth Hormone
- TSH
- ACTH
- Prolactin
- FSH
- LH
Posterior pituitary hormones
- Antidiuretic hormone (vasopressin)
2. Oxytocin
Growth hormone AKA
Somatotropin
TSH is secreted by
Thyrotropes
TSH increases
- Proteolysis of thyroglobulin
- Activity of iodide pump
- Iodination of tyrosine (form T3/T4)
- Size, number, and secretory activity of thyroid cells
TSH inhibited by
T3 and T4
TSH stimulated by
TRH and cold
Adrenocorticotropic hormone (ACTH) stimulates
Cortisol and adrenal androgens secretion
ACTH secreted by
Corticotropes
ACTH stimulated by
- Hypothalamic corticotropin releasing hormone (CRH)
2. Physical or mental stress/ pain
ACTH inhibited by
Cortisol (negative feedback)
Prolactin is inhibited by
Hypothalamic dopamine
AKA Prolactin inhibitory hormone
Stimulates milk secretion and production and inhibits ovulation
Prolactin
Excess prolactin
- Destruction of hypothalamus or prolactinomas
- Galactorrhea
- Infertility
Bromocriptine
Treatment for excess prolactin
Prolactin _______ aspects of immune response
Enhances
FSH and LH are secreted by
Gonadotropes
Functions of FSH and LH
- Stimulate development of ovarian follicles
- Regulates spermatogenesis
- Causes ovulation (LH) and formation of corpus luteum
- Stimulate production of estrogen/progesterone (Female) and testosterone (male)
Activin and Inhibin
Dimer protein complexes in gonads, pituitary, placenta and other organs
Enhances FSH synthesis and secretion
Activin
Helps regulate menstural cycle
Activin
_______ inhibits FSH synthesis and secretion
Inhibin
Posterior pituitary hormones
ADH and oxytocin
Produces milk “letdown” from lactating breast and stimulates uterine contraction
Oxytocin
Oxytocin released in response to
Suckling or conditioned responses (sight, sound, or smell of infant)
Dilation of cervix or orgasm
Uses of oxytocin
Induce labor and reduce postpartum bleeding
Oxytocin inhibited by
Opioids
Oxytocin effects on brain
Relaxation, fearlessness, bonding, contentment
Activated by daily closeness and touch
Melatonin produced by
Pineal gland
Melatonin controls
Reproductive cycle in season breeders , enhances immune function, enhances slow wave sleep
Melatonin released
In circadian cycle (mostly during dark phase)
Hormones synthesized and secreted by liver
- Insulin-like growth factor-1 (IGF-1)
- Angiotensinogen
- Thrombopoietin
- Hepcidin
- Betatrophin
IGF-1
Mediates effects of growth hormone
AKA somatomedin C
Angiotensinogen
Precursor of angiotensin I and II
Thrombopoietin
Stimulates production of platelets
Also produced by kidneys
Hepcidin
Key regulator of entry of iron into cells
Betatrophin
Promotes pancreatic beta cell proliferation
Also produced by adipose
Steroid hormones are conjugated by the _______ and excreted in ______
Conjugated by liver
Excreted in bile
Most common cause of death and stability in young people
Traumatic brain injury
_____ dysfunction common following TBI
Pituitary
Pituitary dysfunction
Most common in GH or FSH/LH
GH deficiency
Inability to concentrate, memory problems, anxiety, and fatigue
LH/ FSH deficiency associated with
Hypogonadism
Central diabetes insipidus
Low ADH