Final

Paracrines

Affect adjacent cells. Do not get into circulatory system. Chemical diffusion into neighboring cell. Short-lived.

Neurotransmitters

Paracrine-type secretions. Synthesized in neuron and released to post synaptic structure. Specialized paracines.

Hormones

Usually produced by endorcine cell in response to stimulus. Carried to target tissue by circulatory system. Target has receptors that recognize hormones. HIghly potent

Neurohormones

Borderline molecules like norepinephrine and epinephrine from adrenal medulla.

Autocrine Secretions

A single cell releases a substance that then has an effect on the original cell that released it.

Pheromone

A "chemical" secreted into external environment to act on a member of the same species.

SImple Feedback Mechanism

Normally involve a negative feedback system that is nonhormonal. Example Glucose and insulin regulation- increasefd plasma glucose causes insulin to be secreted. causes plasma glucose levels to decrease and then insulin secretions also decrease

Nonhormonal feedback

Endocrine cells release the hormone to the target tissue. This causesa biological response that serves to turn off the secretion of the hormone (the hormone itself does not cause the turn off)

Complex Feedback Mechanism (multilevel)

Also involve negative feedback, but the hormone itself causes the stimulus to shut off the secretion, not the biological response. Example hypothalamus releases TRH which stimulates anterior pituitary to release TSH which goes to thyroid to release T3 and T4 which results in biological response. T3 and T4 come back to inhibit the hypothalamus and the anterior pituitary to shut off system

Amino Acid Derivative Hormones

Formed by the simpole conversion of amino acids. e.g thyroxine. typically very small, fairly unusal, and hydrophilic

Peptide and Protein Hormones

Larger peptides and larger protein hormones. Most hormones fall in this category. Hydrophilic

Steroid Hormones

Lipid soluble, hydrophobic, and lypophilic. Synthesized from cholesterol. Since it is hydrophobic a plasma protein must be attached for transport

Synthesis of Peptide and Protein Hormones

Made in cell ribosome (Pro-hormone) and then sent to Golgi apparatus which makes the real thing. Some storage of these hormones. When appropriate cell will exocytose hormone into plasma.

Synthesis of Steroid Hormones

Made from cholesterol (transported via LDLs to cell). When the steroid is made in the cell, it is released. Because of this it takes longer to get a steroid hormone on site than a peptide hormone. These pass right through the membrane. Usually take there action on effector cell in the nucleus;. Travel with transport protein so the dont get filtered and are more soluble.

Protein Hormone Mechanism of Action

Utilize some 2nd messenger. Cannot get through cell membrane easily, so their response is mediated via a receptor. Some change permeability of the membrane

Steroid hormone Mechanism of Action

Pass right throug the membrane. Receptor usually in nucleus. BInd receptors and alter the DNA machinery of the nucleus

Pituitary Gland

Also known as hypophysis. Located at base of brain and protected by sphenoid bone. Closely asscoiated with hypothalamus. Divided into 2 seperate portions, which are very different and have different embryological origins. Anterior and Posterior Pituitary

Anterior Pituitary

Also known as Adenohypophysis. Derived from Rathke's Pouch (from developing mouth in an embryo) Pouch surrounds infundibulum until adulthood. Pars tuberalis is part of AP and wrapped aroung infundibular stalk. . Hypothalamus releases inhibiting or releasing factors into portal system that travels to anterior pituitart and causes it to secrete. Secreted into primary plexus then down hypophyseal portal vein to secondary plexus to be secreted into AP to affect target cell type

Posterior Pituitary

Known as Neurohypophysis. From the developing brain of the embryo(infundibulum gives rise to PP) Hypothalamus communicates via neural relationswhip. Infundibular stalk contains nerve fibers from hypothalamus and end in PP next to capillary bed. The nerve fibers are Supraoptic nucleus produces ADH and Paraventricular nucleus produces oxytocin.

Anterior Pituitary cell types

1. Somatotrophs

2. Lactotrophs

3. Corticotrophs

4. Thyrotrophs

5. Gonadotrophs

Somatotrophs

40-50% of cells. Make human groeth hormone. Most prevalent of cells

Lactotrophs

10--15% of cells. Make Prolactin

Corticotrophs

15-20% of cells

Make Adrenalcoricotrophic hormone

Make Melanocyte-stimulating hormone

Thyrotrophs

3-5% of cells

Make Thyroid-stimulating Hormone

Gonadotrophs

10-15% of cells

Make Follicle Stimulating Hormone

Make Lutenizing Hormone

Thyrotropin-releasing hormone (TRH)

Stimulates release of TSH and Prolactin

Corticotropin-releasing Hormone (CRH)

Stimulates release of ACTH and MSH

Gonadotropin-releasing Hormone (GnRH)

stimulates release of FSH and LH

Growth hormone-releasing hormone (GHRH)

Stimulate release of hGH

Growth hormone-inhibiting hormone (GHIH)

Also known as somatostatin . Inhibits release of hGH

Prolactin-inhibiting hormone (PIH)

Inhibits release of prolactin

Follicle Stimulating Hormone (FSH)

Causes growth and maturation of the ovarian follicle

Influences estrogen secretion from the follicle

Stimulates sperm production

Secreted from Anterior Pituitary

Lutenizing Hormone (LH)

From Anterior Pituitary

Surge of LH needed for ovulation

Causes formation of the corpus luteum (follicle reorganizes after ovulation to form the corpus luteum)

Causes secretion of testosterone by the Leydig cells

Adrenocorticotropic Hormone (ACTH)

From Anterior Pituitary

Stimualtes the production of the glucocorticoids by the adrenal cortex (primarily cortisol in humans)

Thyroid Stimulating Hormone (TSH)

From Anterior Pituitary

Causes growth/maturation of the thyroid tissue

Stimulates the secretion of the thyroid hormone

Prolactin

From Anterior Pituitary

Causes secretion of milk in the mammary glands

Alveolar sacs in breasts are lined with secretory epithelial cells that synthesize and secrete milk into alveoli. Prolaction causes the secretion of milk into the sacs not the "letdown" of the milk to the nipple

Melanocyte Stimulating Hormone (MSH)

Associated with the intermediate lobe (part of anterior pituitary)

NO significant role in humans (we have melanin and melanocytes, but no MSH) although it may play a role in appetite suppression.

Can camouflage some animals. MSH favors distribution of melanin throughout melanocytes. If melanin is distributed cell takes on a darker color.

ACTH is MSH close cousin patients with higher ACTH may take on darker color due to similarity to MSH

ADH

Produced by supraoptic nucleus in the hypothalamus and transmitted down neurons to be stored and released from the posterior pituitary. Has a role in urine production and regulating BP

Oxytocin

Produced by paraventricular nucleus in hypothalamus and transmitted down neurons to be stored and released from posterior pituitary. Stimulates milk letdown and plays a role in parturition. In milk let down once milk is in sacs myoepithelial cells have oxytocin receptors when stimulated these cause contractions which lets milk down to nipple. In parturition oxytocin hastens in properly prepared uterus. Also assists in sperm transport. Released in female during sex to help sperm motility

Pineal Gland

Not part of pituitary posterior to thalamus. Secretes Melatonin

Melatonin

involved in certain functions in cyclic activity.More is secreted at night. MAy be involved in affective disorders, PMS, puberty onset, and seasonal breeding in animals.

Human Growth Hormone (hGH)

MOst abundant hormone in anterior pituitary. Has effects at many locations such as fat tissue, muscle tissue, and cartilage. Increases size of a number of tissues. A protein made of 101 amino acids.Has an effect on Protein metabolism, Lipid Metabolism, and Carbohydrate Metabolism

hGH effects on Protein Metabolism

Enhances protein synthesis by increasing amino acid uptake into the cells, increasing RNA synthesis, and increasing ribosomal activity. Increase in lean body mass and increase in size of other organs

hGH effect on Lipid Metabolism

Causes lipolysis: increases lipid breakdown, which leads to inc. in plasma fatty acids

Enhances Beta oxidation (fatty acid usage as fuel) which leads to ketone body production

hGH effect on Carbohydrate Metabolism

Decreases cellular uptake of glucose into muscle and fat cells

Increase plasma glucose levels which can increase insulin secretions and may lead to diabetes

Makes fat and muscle cells more resistant to insulin

Counter-regulatory to i

Factors that effect growth

1. Genetic background

2. Diet: low protein can cause improper growth

3. Freedom from chronic disease and stress

4. Hormones: Insulin, sex hormones, thyroid hormones

Hypertrophy

An increase in size of cells

Hyperplasia

An increase in number of cells

Intramembranous Ossification

Occurs in periosteum. hGH stimulate osteoblasts in periosteum. Causes bones to grow in diameter. How bones repaired in injury. Smaller, flat bones solely grow this way.

Endochondral Ossification

Occurs mostly in long bones. Cartilage precursor (prototype). Appears at 2 centers: primary ossification and secondary ossification centers. At the centers bone replaces cartilage. Stimulates the activity of osteoblasts in periosteum and stimulates prochondrocytes. Continues until adolescnce until cartilage is all overtaken abd epiphyseal plates fuse

Role of Somatomedins (IGFs)

hGH does not always actually bind to receptors on target cells. It increases production of somatomedins (insulin-like growth factor) which act on target tissue. 2 types: IGF I and IGF II which are made mainly in liver. Increase in IGF I at puberty

Regulation of hGH

GHRH and GHIH (somatostatin) released by hypothalamus influence hGH. Released into anterior pituitary via hypophyseal portal system. hGH secreted in adults during sleep and in children in the sleep/wake cycle. Things that also stimulate secretion are:

1. Low plasma glucose levels

2. Low plasma fatty acid levels

3. High plasma amino acid level

4. Sleep

5. Stress

6. Exercise

7. Feedback

Pituitary Dwarf

A person who is short stature typically is due to too little hGH or GHRH (most common type)

Laron Dwarf

A short statured person with:

1. Normal to high levels of hGH

2. And inability to synthesize IGF I

3. Mutated hGH receptors

4. No increase in IGFs in response to GH

Pygmies

A group of short-satured people with:

1. Low IGF I levels

2. Normal hGH receptors

3. A deficient number of GH receptors

4. Normal IGF II response

Pituitary Gigantism

This is associated with too much hGH, generally due to a pituitary tumor. The tumor occurs in children, who thus may grow to be very tall. These patients are also at risk for diabetes mellitus

Acromegaly

Associated with too much hGH after the fusion of epiphyseal plates

Steroid producing cells

1. Adrenocortical

2. Ovarian

3. Testicular

4. Placental

Cholesterol

Is the parent molecule for steroid hormones. Very little different when looking at them but are biologically very different.

Testes

Primary reproductive structure in male have dual functions. Spermatogenesis and Steroidogenesis). Develop in rear of abdominal cavity and at 7th moth of gestation descend from abdominal cavity through abdominal wall through inguinal canal and into scrotum. Spermatic cord is attached to each and inguinal canal closes tightly around them. Must descend for temp. regulation.

Spermatogenesis

Sperm Production. Cannot occur at 37 degrees C

Steroidogenesis

Androgen production. Can occur at 37 degrees C

Inguinal Hernia

Where inguinal canal does not completely shut around spermatic cord. Part of gut can can bulge through the hole and become strangled and thus surgical repair is usually warranted

Pampiniform Plexus

Helps regulate testes temp. A countercurrent blood flow to and from the testes. The blood leaving the testes cools the blood coming to the testes.

Vericocele

Like a vericose vein but in pampiniform plexus. Disrupts the countercurrent blood flow. Temp gets too high and testis is usually sterile

Cremaster Muscle

Helps in testes temp. regulation. Muscle can elevate or lower the testes to alter the temp of them . When temp is too high muscle relaxesa so testes farther down in scrotum. When temp too low muscle contracts and pulls testes closer to body

Cryptorchidism

This pathology is fairly uncommon in full term pregnancies. It usually occurs in premature babies. The testes do not descend properly during fetal life

Longitudinal Sections

200-300 cone shaped lobules within each testis. Contain Seminiferous tubules

Seminiferous Tubules

1-3 of these within each lobule. Highly convoluted. Sperm producing apparatus. Contain Germ cells and Seroli Cells

Germ Cells

Found in seminiferous tubules. All in different stages of diiferentiation or maturation (meiosis)

Sertoli Celld

In seminiferous tubules. Have many functions.

1. Provide blood-testes barrier

2.Nourish Sperm

3.Phagocytize germ cells

4. Produce tubular fluid that help transport sperm

5. Produce androgen binding proteins

6. Produces inhibin

7. Increase activity of enzyme P450 aromatase

8. Produce plasmiogen activating factor

9. Increase synthesis of transferrin

10. Produces Mullerian-inhibiting factor

Blood-testes barrier

Immune system learns what it itself and what isnt. In males sperm not made until puberty. They seem new to body so immune system could attack. This protects sperm from immune system

Androgen binding protein

Allow testes to maintain an increased concentration of androgens

Plasminogen activating factor

Causes formation of plasmin which helps "digest spem away" from edge of lumen of the seminiferous tubules

Interstitial Cells of Leydig

Located in space btwn seminiferous tubules. Produce Testosterone, DHT, and Estrogen. Testosterone is predominant can go to targert tisue or be converted by 5-alpha-reductase into DHT. DHT can also affect target tissues and is more potent than testosterone and affects different tissues. Estrogen can be made from testosterone via P450 aromatase. Normally no expression of estrogen however synthetic testosterone can cause testosterone sensitivity and allow estrogen expression

Gynecomastia

Rudimentary breast development in a male when too much estrogen expressed

Epididymis

Set on each of the testes. Sperm are stored and matured

Vas Deferens

Leads away from epididymis. Can have a vasectomy where vas deferens is tied on eithr side;. Male can still ejaculate but no sperm.

Seminal Vesicle

Contributes 60% of the semen volume and secretes nutrient rich secretions such as fructose, prostaglandins, and fibrinogen

Prostate

Contributes 30% of semen. Located where urethra comes out of bladder. Produces thin milky alkaline secretion which helps spem survive in the vagina. The vagina is acidic whic is not good for sperm life or motility

Corpus cavernosum

Spongy tissue in penis that gets engorged with blood to cause an erection

Erection

Parasympathetic phenomenon that causes dilation of arterioles to penis and cause corpus cavernosum to fill

Ejaculation

Sympathetic phenomenon that occurs when sexual stimulation causes contraction of epididymis, the vas deferen, adn the prostate

Female Sex Act Parasymp.

Vasodilation of arterioles to clitoris and labia in response to tactile and/or psychological stimulation. AFluid forced out vaginal capillaries into vaginal lumen for lubrication

Female Sex Act Sympathetic

When stimuli sufficient the female version of ejaculation takes form of contractions of the pelvic membrane

Testosterone levels

Surge of androgens during fetal life from 8 weeks until 18 weeks develops male reproductive structure. Then around 2-3 monthsafter parturition another surge of androgens. Next surge not until puberty continues until 20-25 when they slowly decline never abrupt decline in plasma testosterone

Testosterone role in Genetic sex determination

The sex of the child is determined by chromosome of the sperm fertilizing the ovum

y= male

x=female

Testosterone role in Gonadal sex determination

Default system is female. If Y chromosome present then SRY region codes for protein :testicular determining factor" causes gonads to become testes and develop along male lines

Testosterone role in Phenotypic Sex

The default is always female. If embryonic structures are not exposed to DHT which is made from testosterone then they will develop female external genitalia. Each embryo has immature versions of wolffian system and Mullerian system before differentation. Testosterone made by fetal testes due to HCG which stimulates wolffian system and fetal testes make Mullerian Inhibiting Factor. Testosterone converted by 5-alpha-reductase into DHT which makes male genitalia

Adrenogenital Syndrome

Excess Androgens

Example: If XX embryo ovaries would develop, a female reproductive tract, and male external genitalia

Androgen Insensitivity Syndrome

When androgen receptors are insensitive. If in an XY embryo it leads to no wolffian development, no Mullerian development( still has inhibiting factor), and female external genitalia

Testosterone Masculinization of brain

The default system is female cyclic brain but fetal testes produce androgens some get converted to estrogen. Females have alpha-fetal protein which ties up estrogen at fetal brain level, but males lack this protien so estrogen causes brain to develop male (acyclic)

Androgen Primary Sex Characteristics

1. Enhance spermatogenesis

2.growth and maturation of reproductive tract at puberty

3. maintain reproductive tract in adulthood

4. responsible for libido

Androgen secondary sex characteristic

1. Body hair

2. Baldness

3. Enlarged larynx, deeper voice

4. thickening of skin

5. increased secretion of sebaceous glands

6. Stimulate bone growth

7.stimulate closure of epiphysea plates

8.increase protein secretion

9. Increased erythropoeisis

10. Increase BMR

11.Increase LDL

12. Increaswe synthesis of androgen-binding protein

13. favor fat deposition

Fetal Testosterone

Epididymis, Vas deferens, Seminal vesicle, Seminiferous tubules

Fetal DHT

Penis, Scrotum, Prostate

Adult Testosterone

Penis, Seminal Vesicle, Sperm production, skeleton and muscle, libido, larynx

Adult DHT

Scrotum, Prostate, Hair, Sebaceous Gland

Control of testicular function

Hypothalamus makes GnRH has an effect on FSH which causes sertoli cells to increase androgen binding protein and promote spermatogenesis and LH promotes testosterone production. Spermatogenesis and inhibin shuts off FSH but not LH

Xenoestrogens

foreign estrogens that have been linked to : declinign sperm count, decline in volume of ejaculate, testicular cancer, reproductive tract abnormalities, increase cryptorchidism and hypospadia, increased in breast cancer and causes gender bending

Ovaries

Outer portion is germinal epithelium. Outer zone is cortex which contains ova which are in varying stages of development. Inside ovaries is stroma. Ovaries produce mature ova along with sex hormones

Oviducts

One on each side of ovary have fingerlike projections called fimbriae which beat back and forth to direct ova into oviduct. Oviduct extends down to uterus. Fertilization occurs in first third of oviduct

Uterus

Provide environment for developing fetus and provides force for pushing fetus through cervix during parturition. Has 3 layers. Epimetrium (outside), myometrium (muscle layer), and endometrium ( inner portion). Under hormonal control. endometrium sloughs off during menstruation and myometrium site of cramping. Cervix is narrow and contains a mucus that is thin during ovulation and thick during pregnancy

Vagina

Passageway for menstrual flow, childbirth, and sperm. Tubular fibrous organ lined with mucus secreting cells. May have folds of vascularized tissue that cover orifice called hymen.

Vulva

Term for femal external genitalia including mons pubis, the labia, clitoris, vestibule

Mons pubis

Adipose tissue covered by skin and hair that serves as a cushion for pubic symphysis

Labia

There is labia majora and minora

Clitoris

small cylindrical mass of tissue that engorges with blood and erects during sex

Vestibule

cleft btwn labia minora. hymen, vaginal orifice, external urethral orifice and openings to mucus producing glands are found here.

Follicular development

Primordial germ cells produce oogonia under mitosis untilo 20-24 weeks fetal development. until 6 months after parturition oogonia undergo prophase and become primary oocytes. the process is arrested for awhile. next naked oocyte becomes primordial follicle by laying down 1 layer of granulosa cells around oocyte. These can either mature and ovulate or become atretic. Before puberty these become primary follicle. follicles will mature and ovulate

Ovarian Cycle

everything that happnes in 28 day cycle. Follicular phase days 1-14 and luteal phase days 15-28

Follicular phase

primordial follicle grows granulosa cells proliferate. the zona pellucida found btwn ova and granulosa cells develops. Under FSH more granulosa proliferation and new outer thecal layer . NOw 2ndary follicle. Thecal and granulosa layer produce estroge 2ndary follicle shows a cavity filled w/ estrogen, electrolytes and plasminogen. 2ndary become tertiary and continues estrogen secr. thecal becomes theca interna and externa. Finally a mature folliclesurge of LHplasmin causes follicle to burst out

Luteal Phase

After ovulation follicle is transformed into corpus luteum which produces estrogen and progesterone for days past ovulatio unless pregnancy. No pregnancy corpus luteum degenerate and no longer makes estr. or progest. and becomes corpus albicans. Granulosa and thecal cells form corpus luteum

Endometrial cycle

Comp0osed of menstrual phase, proliferative phase and secretory phase

Menstrual phase

Sloughing off of endometrium days 1-5

Proliferative phase

primarily influenced by developing follicle endometrium getting thicker due to estrogen days 6-14

Secretory phase

endometrium is lush and edematous and ready for implantation

Cervical Mucus cycle

Mucus within the cervical neck that foes through a cycle which is dependent of hormones. There is an estrogen phase and luteal phase

Estrogen phase (Mucus cycle)

mucus is thin watery advantageous for sperm to travel to oviducts to fertilize ovum. estrogen dependent, occurs during middle of cycle

luteal phase (mucus cycle)

thick viscous acidic mucus this is progesterone dependent

Final

Biology 5600 with Witt at Auburn University

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