Exam II Flashcards
A hormone is a product of an endocrine gland released directly into the bloodstream that acts how?
Peripherally on distant specific target cells
Exerts trophic effect
What sort of local effect of a hormone regulates processes in neighboring cells?
Paracrine
What sort of local effect of a hormone “acts back” to regulate processes within the same cell?
Autocrine
What sort of local effect of a hormone regulates processes within the cells of origin without being secreted?
Intracrine
What sort of local effect of a hormone originates in the neuron, undergoes axonal transport, and is carried distally by a blood vessel or synaptic transmission?
Neurocrine
What hormone class contain a carbohydrate moiety (helps w assembly, secretion, and biologic activity?
Glycoproteins
What hormone class is derived from AAs and produced from a gene that is transcribed into mRNA?
Peptides
What hormone class is derived from cholesterol and has a cyclo ring?
Steroids
What hormone class is derived from tyrosine?
Amines
Which class do the following hormones belong to? FSH TSH LH hCG
Glycoproteins
Which class do the following hormones belong to? ACTH Angiotensin Calcitonin PTH Melanocyte stimulating hormone (MSH) GF Oxytocin, ADH, AVP Prolactin, GH Somatostatin, insulin, glucagon
Peptides
Which class do the following hormones belong to? Aldosterone Cortisol Estradiol Progesterone Estrogen Testosterone DHEA Vitamin D
Steroids
Which class do the following hormones belong to? Epi/ NE Dopamine Thyroxine (T4) Triiodothyronine (T3)
Amines
How are hydrophilic hormones transported, and which classes do they include?
In the blood stream
Peptide hormones and catecholamines
How are hydrophobic hormones transported, and which classes do they include?
Bound to proteins
Thyroid and steroid based hormones
What type of proteins provide a reserve of hormones that can be called upon to replenish the free pool?
Binding proteins (keeps hormones in blood in inactive state)
What regulates inactivation/ excretion of hormones to contribute to plasma hormone concentration?
Degradation/ inactivation in liver/ kidney via glucuronidation and sulfate conjugation
What does internalization of hormone/ receptor complex in peripheral tissues contribute to?
Plasma hormone concentration
What group of hormones enters the nucleus, binds to receptors on DNA and activates specific thyroid or steroid responsive elements?
Group I
What hormone has the following characteristics?
Membrane located enzyme: adenylyl cyclase
2nd messenger: cAMP
Kinase: cAMP dependent protein kinase
Group IIA
What hormone has the following characteristics?
Membrane located enzyme: guanylyl cyclase
2nd messenger: cGMP
Kinase: cGMP dependent protein kinase
Group IIB
What hormone has the following characteristics?
Membrane located enzyme: phospholipase C
2nd messenger: DAG and IP3
Kinase: protein kinase C, calmodulin dependent protein kinase
Group IIC
What hormone has the following characteristics?
Kinase: serine or threonine kinase
Group IID
Once a peptide hormone is translated into mRNA + amino acid in ribosome, what happens to it?
Preprohormone > cleaved in ER > prohormone > cleaved in Golgi > hormone > stored in granules
What is the site of synthesis for steroid hormones?
Cytosol, ER, mitochondria
What is the site of synthesis for amines?
Enzymatic in cytosol, follicular cell and colloid of thyroid
What is the middle step conversion from testosterone to dihydrotestosterone?
Androgens formed in androgen-dependent tissues
What is the middle step conversion from testosterone to estradiol?
Conversion to E2 in brain/ testes
What type of hormone secretion is activated by blood borne substrate?
Humoral
What type of hormone secretion occurs via extension of CNS that signals a gland to secrete hormone?
Neural
What type of hormone secretion uses hormones to regulate secretion?
Hormonal
What is the most common type of feedback mechanism?
Negative (hormone inhibits further secretion of hormone)
What 2 hormones are regulation by a positive feedback mechanism?
Estrogen, oxytocin
What type of hormone action is described as the following: one hormone cannot exert full effect without presence of another?
Permissiveness
What type of hormone action is described as the following: hormone regulates # and/or affinity of its own receptor?
Autologous up/ down regulation
What type of hormone action is described as the following: hormones regulates # and/or affinity of another hormone’s receptor?
Heterologous up/ down regulation
What type of neurons begin in the hypothalamus, project their axons down the infundibular process and terminate in the posterior pituitary?
Magnocellular neurons
What type of neurons are include a neurovascular link between the hypothalamus and anterior pituitary and ultimately release hormones into systemic circulation?
Parvicellular neurons
Is the anterior or posterior pituitary responsible for metabolism, growth/ development, reproduction, lactation, and response to stress?
Anterior
Is the anterior or posterior pituitary responsible for water balance, parturition/ lactation, regulation of BP, cardiac function, and diuresis?
Posterior
What hormone increases synthesis of GH and exerts its effect on many tissues?
Growth hormone releasing hormone (GHRG)
What hormone increases synthesis of TSH and prolactin and exerts its effects on the thyroid gland and mammary glands?
Thyrotropin releasing hormone (TRH)
What hormone decreases synthesis of GH and TSH?
Somatostatin
What hormone increases synthesis of LH and FSH, is synthesized in the gonadotrophs, and exerts its effects on the gonads?
Gonadotropin releasing hormone (GnRH)
What hormone increases synthesis of ACTH and exerts its effects on the adrenal glands?
Corticotropin releasing hormone (CRH)
What hormone increases synthesis of Prolactin and exerts its effects on the mammary glands?
Prolactin releasing factor (PRF)
What hormone inhibits prolactin synthesis?
Dopamin (Prolactin inhibiting hormone, PIH)
Which hormone is responsible for growth via IGF production in the liver and energy metabolism?
Growth hormone releasing hormone (GHRG)
Which hormone is responsible for growth of the thyroid gland, synthesis of T3/T4, breast development, and milk production?
Thyrotropin releasing hormone (TRH)
Which hormone is responsible for ovulation/ secretion of estrogen, secretion of testosterone from Leydig cells, development of follicle, and initiation of spermatogenesis?
Gonadotropin releasing hormone (GnRH)
Which hormone is responsible for growth of the adrenal gland and synthesis of corticosteroids?
Corticotropin releasing hormone (CRH)
Which hormone is responsible for breast development and milk production?
Prolactin releasing factor (PRF)
Why type of neurons produce ADH/ AVP and oxytocin?
Magnocellular neurons
What hormones and neuropeptides with a short plasma half life?
ADH/ AVP and oxytocin
Is increased osmolarity or a decreased blood volume a stronger stimulator for release of ADH/ AVP?
Increased osmolarity (> 1% above normal Na threshold)
How do ADH/ AVP increase blood volume/ pressure and decrease osmolarity once they are released from the hypothalamus/ magnocellular neuron?
V2 receptor on principal cells of nephron activated
Increased aquaporins 1-4
Water reabsorbed from nephron
What 2 primary actions contribute to stimulation of oxytocin release?
Cervix stretching (parturition) Suckling on lactating breast
What is the highly sensitized OT receptor in the uterus mediated by?
OT/ progesterone
Gap junctions in smooth muscle cells
(200x in pregnant uterus)
Is continued suckling a positive or negative feedback loop?
Positive
Is suckling required for secretion of milk?
No- conditioned response to sight, smell, and sound of infant
What specific OT axis is present in the heart?
OT-natriuretic peptide-nitric oxide axis
How does OT contribute to cardiac function after ANP/ BNP are released from cardiomyocytes?
ANP stimulates release of NO from vascular epithelium
Once OT binds to receptors, what happens in vascular tissue?
NO dependent vasodilation leads to vasodilation/ decreased BP
Once OT binds to receptors, what happens in cardiac tissue?
Synthesis of ANP and NO leads to negative inotropic/ chronotropic effects which leads to ANP binding to NPR-A to cause vasodilation
With respect to renal function, at physiological concentrations, OT stimulates what?
Diuresis and natiuresis via renal OT receptor
Ateriole vasodilation, diuresis, natriuresis, kailuresism and decreased plasma volume are renal function responses to what hormone?
Oxytocin
How does increased plasma/ synthesis of OT affect production of cortisol?
Decreased production via decreased hypothalamic CRF
What is the site of spermatogenesis?
Seminiferous tubules
What is the testosterone mediated process that occurs along the length of the seminiferous tubules?
Spermatogenesis
What process results in the proliferation and differentiation of spermatogonia?
Mitosis
What is the result of meiosis from undifferentiated diploid germ cells?
Haploid spermatocyte that leads to 16 spermatids
What is the name for the packing and maturation of sperm in male reproduction?
Spermiogenesis
What does synctium ensure?
That haploid cells contain either X or Y chromosome
What sets the rate for spermatogenic cycles?
Retinoic acid signaling within Sertoli cells
How long is a spermatogenic cycle?
16 days (~72 days to make sperm, 6 stages)
Around how mature sperm are produced daily?
~100-200 million
At what point in gestation to the testes descend, and why is this important?
~7 months
Allows for cooler temps to prevent lysosomal destruction
What determines the ultimate spermatogenic potential of the testes?
of Sertoli cells that occur in development
What provides the blood-testes barrier?
Tight junctions between Sertoli cells
What allows for the following:
Developing sperm travel to lumen
Prevents immune cells from accessing genetically variant spermatozoa
Required for fertility
Blood-testes barrier
What is the role of gap junctions between spermatocytes and Sertoli cells?
Permits transfer of nutrients
What allows the Y-sperm to transport necessary gene products to the X-sperm?
Cytoplasmic bridges joining early spermatids
What cell is responsible for the protection and physical, metabolic, and nutritional support to the developing sperm?
Sertoli cells
What cell absorbs excess cytoplasm and wastes from developing sperm?
Sertoli cells
What cell is responsible for regulation of internal environment of seminiferous tubule?
Sertoli cells
What cell secretes seminiferous tubule fluid to aid in flushing sperm to epididymis?
Sertoli cells
What cell produces androgen binding protein to sequester T?
Sertoli cells
What hormones stimulate Sertoli cells and what hormone do Sertoli cells release?
Stimulated by T and FSH
Release Inhibin
What cell secretes anti-mellerian factor during development?
Sertoli cells
At what point do Sertoli cells cease production?
At end of puberty
Hypogonadism is a condition in which the testicles are smaller than N size and have what?
Below normal sperm counts
What is the process by which spermatids mature in spermatozoa?
Spermiogenesis
In the maturation of spermatids, what happens to the head?
Elongates and cytoplasm is lost
In the maturation of spermatids, what happens to the nucleus?
Remodels and chromatin condenses
In the maturation of spermatids, what happens to the lysosomes?
Form acrosome
In the maturation of spermatids, when does transcription stop?
2 weeks before maturation
In the maturation of spermatids, what segment is involved with the mitochondria moving to the base to power the sperm?
Midpiece
What is the name of the process in which mature sperm are extruded from Sertoli cells into the lumen of the seminiferous tubules?
Spermiation
In spermiation, what do the sperm pass through for processing/ storage?
Rete testes
What is the name of the maturation area located near the upper portion of each testicle that holds sperm after they are transferred under pressure and smooth muscle contraction?
Epididymis
During spermiation, are sperm capable of movement and/or fertilization?
No
During spermiation, what happens after contraction of myoepithelial cells?
Spermatozoa propelled into vas deferens
What 2 things control spermatogenesis?
Synergistic action of T and FSH
Presence of adequate Sertoli cells
Which hormone involved in spermatogenesis acts by pulsatile release?
GnRH
Which hormone involved in spermatogenesis sensitizes Sertoli cells to T and promotes Inhibin and androgen binding protein (ABP) secretion from Sertoli cells?
FSH
Which hormone involved in spermatogenesis stimulates cholesterol desmolase within Leydig cells to produce testosterone?
LH
In spermatogenesis, what do T and Inhibin regulate?
T regulates LH and FSH
Inhibin selectively regulates FSH
T can be peripherally converted to dihydrotestosterone or estradiol in target tissues via what enzymes?
5a-reductase, aromatase
What is the result of T binding to androgen binding protein (ABP) from Sertoli cells?
T becomes concentrated in seminiferous tubules
T circulates within peripheral circulation bound to what hormone?
Sex hormone binding globulin (SHBG)
What is the role of testosterone in embryonic/ fetal development? (2)
Masculine reproductive tracts/ external genitalia
Descent of testes
What is the role of testosterone in sex-specific tissue after birth? (3)
Maturation of reproductive system at puberty
Spermatogenesis
Maintenance of reproductive tract
What is the role of testosterone in reproduction related effects? (2)
Increased sex drive
Controls gonadotropin secretion
What is the role of testosterone in secondary sex characteristics?
Male pattern hair growth, deepens voice, muscle growth/ male adiposity
What areas of the brain does T contribute to the development of?
Pre-optic area, hippocampus, amygdala
What hormone is responsible for increased protein anabolic effects?
Testosterone
What hormone is responsible for promoting bone growth at puberty and closing epiphyseal plates?
Testosterone
What hormone has the potential to induce aggressive behavior?
Testosterone
How potent is dihydrotestosterone compared to testosterone?
2x
Is T or DHT responsible for differentiation of the Wolffian ducts into the epididymis, vas deferens, and seminal vesicle?
T
Is T or DHT responsible for increased muscle mass, pubertal growth spurt, deepening of voice, and growth of penis and seminal vesicles?
T
Does T or DHT play a role in negative feedback on the anterior pituitary?
T
Is T or DHT responsible for libido?
T
Is T or DHT responsible for differentiation of the penis, scrotum, and prostate?
DHT
Is T or DHT responsible for male hair pattern and male pattern baldness?
DHT
Is T or DHT responsible for sebaceous gland activity?
DHT
Is T or DHT responsible for growth of the prostate?
DHT
What is cryptorchidism and how does it affect fertility?
Undescended testes
Affected men unable to produce viable sperm
If a pt has < 15 million sperm/ mL of semen, along with poor sperm motility and defects in sperm morphology, what condition do they have?
Oligozoospermia
How can pollution such as polychlorinated biphenyls (PCBs) and heavy mental exposure (lead) result in oligozoospermia?
Reduce sperm count and sex hormone
What environmental factors can contribute to oligozoospermia?
Pollution, XR, lifestyle (tobacco, alcohol, steroids), stress
What mechanism can contribute to oligozoospermia via activation of the HPA axis and can influence normal function of the HPG axis?
Stress
What is the treatment for oligozoospermia?
Rx, lifestyle changes, assisted reproduction therapy, testicular sperm in place of ejaculated sperm
How can things like tight clothing, hot tubs, and sitting too long result in low sperm counts?
Interference with ability of scrotum to cool testes
What are the effects of marijuana on fertility?
Reduces fertility by decreasing sperm #’s, altering morphology, and reducing sperm activity
Endocannabinoid receptors in sperm present in the HPG axis have what effect?
Suppressive effect
Use of what can lead to altered male sex hormones?
Marijuana
Androgen Deficiency in Aging Males is aka what?
MANOPAUSE
ADAM is ultimately due to a decreased production of T and sperm during what phase?
Senescence
If a pt presents w the following, what should you tell them they are experiencing?
Changes in mood, energy and appetite
Decreased bone formation, muscle, sex drive, body height, Hct, facial hair
ADADM (manopause)
How does ADAM (manopause) relate to CV disease?
Increased risk
Exogenous testosterone will affect the endocrine system by decreasing what?
LH, FSH, sperm production
Exogenous testosterone will affect the endocrine system by increasing what?
Free estrogens, peripheral conversion of T to estrogen
What are the following risks associated with? CV disease Visceral obesity Erythrocytosis Fluid retention BPH Prostate cancer Acne Hepatotoxicity Infertility Obstructive sleep apnea Gynecomastia and breast CA Behavioral issues Depressed immunity
Exogenous testosterone
What stimulates pubic and axial hair growth?
DHEA via adrenal cortex
What stimulates male hair growth and is the cause of male pattern baldness (male androgenic alopecia)?
DHT
Synergism of DHT and IGF-1 result in what?
Beard growth
Scalp hair growth is reduced by what?
DHT and transforming GF beta1 (TGF-beta1)
What occurs with 5alpha-reductase conversion of T to DHT?
Hair follicle miniaturization
Proof that DHT stimulates male hair growth and is the cause of male pattern baldness (male androgenic alopecia) can be seen via what populations?
Castrated males, eunuchoidal pts with androgen insensitivity syndrome and those with 5alpha-reductase deficiency DO NOT go bald
What drug is used to treat androgenic alopecia or enlarged prostates by blocking DHT?
Propecia/ finasteride
5alpha-reductase antagonists binding irreversibly to an enzyme to prevent conversion from T to DHT is the MOA for what drug?
Propecia/ finasteride
What are the SE’s of Propecia/ finasteride?
ED, loss of libido, reduced ejaculate
Accessory organs collectively produce what % of semen, making the remaining composition as sperm?
90% (remaining 10% is sperm)
What % of ejaculate is contributed by the seminal vesicles?
60%
What % of ejaculate is contributed by the prostate?
20%
What % of ejaculate is contributed by the bulbourethral glands?
10%
What accessory organ in semen production contributes fructose, prostaglandins, and clotting factor?
Seminal vesicles
What is the role of fructose and prostaglandins in ejaculate?
Fructose nourishes sperm
Prostaglandins stimulate M/F reproductive tract
What accessory organ in semen production contributes an alkaline fluid to counter the acidic vaginal environment?
Prostate
What triggers clotting to keep sperm in the vagina?
pH
What accessory organ in semen production contributes lubrication fluid?
Bulbourethral glands
What 3 things stimulate erection?
- Sexual thoughts (higher brain center)
- Mechanical stimulation of glans
- Periodic PNS impulses from sacral erection generating center
What is the integration site for CNS control of erections?
Medial preoptic area (MPOA)
Once the MPOA receives sensory input from the amygdala, where does it send impulses?
Paraventricular nuclei and periaquaductal gray matter in sacral spinal cord
How does mechanical stimulation of the glans stimulate an erection?
Sensory feedback to sacral erection generating center (S2-4)
What results in vasodilation of penis arterioles?
PNS release of NO
NO activation of guanylyl cyclase/ production of cGMP activates myosin phosphatase in SM. What effect does this have on Ca2+ and what is the overall effect on the penis?
Decreases intracellular Ca2+ to promote relaxation and stimulate erection
What role do skeletal muscles play in periodic PNS impulses from sacral erection generating center stimulating an erection?
Skeletal muscles at the base of the penis result in mechanical compression of veins
What degrades cGMP to ultimately block the pathway of erection stimulation?
Phosphodiesterase
Periodic PNS impulses from sacral erection generating center stimulating an erection involves PNS stimulation of what glands?
Bulbourethral glands
Tonic SNS stimulation leads to what?
Flaccid penis
Concurrent SNS inhibition and PNS stimulation allows males to get an erection in how long?
5 seconds
Contraction of what structures limit BF into the penis, ultimately leading to a flaccid state?
Helicine arteries and trabecular smooth muscle
Relaxation of what structure by NO and increased BF into where induces engorgement and leads to an erect state?
Relaxation of helicine arteries
Increased BF into cavernous space
Compression of what structures decreases venous outflow in an erect state?
Subtunical venules
Ejaculation is divided into what 2 stages and is affected by stimulation of what?
Emission and expulsion
SNS and somatic stimulation
During emission, SNS stimulation from L1/2 causes semen to enter the urethra from contraction of what glands?
Accessory glands
During emission, once semen enters the urethra from contraction of the accessory glands, SNS then stimulates what?
Smooth muscle, leading to further contraction of accessory glands
During expulsion, somatic nerve impulses with rhythmic activation of skeletal muscles at the base of the penis is triggered by what?
Filling of urethra
What is the average amount of total ejaculate produced (after several days of abstinence)?
2-6 mL
How many sperm are present in each mL of ejaculate?
~20-100 million
What is the ejaculation pathway? (4 steps)
Vas deferens
Ampulla
Urethra
Exit
What results in the urethral sphincter and semen entering the bladder?
Retrograde ejaculation
Psychic stimuli target what parts of the brain contributing to male sexual response?
Cortex, limbic, hypothalamic
Psychic stimuli + physical stimuli lead to what as part of the male sexual response?
PNS arterial dilation followed by SNS impulses
NO, Ach, vasocongestion, penile engorgement, and stimulation of bulbourethral glands contribute to what aspect of the male sexual response?
PNS arterial dilation
Emission + expulsion of semen, and contraction of pelvic musculature to enhance sperm mobility contribute to what aspect of the male sexual response?
SNS impulses
What are the 4 steps that make up orgasm/ resolution?
- Excitement
- Plateau
- Orgasm
- Resolution
What stage of male sexual response is marked by flushed skin, increased muscle tone, nipples hardening, increased BF to genitals, scrotum tightens, and presence of lubricating emissions from penis?
Excitement
