Hormones, Reproduction, & Development

Hormones, Reproduction, and Development: Functions

• Hormones coordinate and manage cell activities.
• Hormones facilitate sequential changes in growth, development, and maturation.
• Hormones play a role in maintaining homeostasis.

Signaling Molecules

• Hormones coordinate and manage cellular activities.
• They are responsible for growth, development, maturation, and homeostasis.

Target Cells and Hormone Effects

• Hormones specifically target cells.
• Target cells possess specific receptors for hormones.
• Hormone binding triggers a cellular reaction.
• A single hormone can affect many target cells.

Endocrine Hormone Definition

• Endocrine hormones are chemically active signaling molecules.
• These hormones are synthesized and secreted by endocrine glands, endocrine cells, and neurosecretory cells.
• They are released into the interstitial fluid and diffuse into the bloodstream to reach target cells.

Endocrine Hormone Secretion

• Endocrine glands, endocrine cells, and neurosecretory cells are structures that secrete endocrine hormones.

Interstitial Fluid

• Interstitial fluid is fluid outside of cells.

Endocrine Hormone Pathway

• The path of endocrine hormones is: secreting cell, interstitial fluid, bloodstream, then target cells

Steroid Hormones

• Steroid hormones are lipid-soluble and pass through cell membranes.
• Their structure includes four fused carbon rings.
• They diffuse directly into cells.
• They enter the cell, bind to a receptor in the nucleus, and the hormone-receptor complex activates gene activity.
• Protein is formed and carries out a cell response.

Non-Steroid Hormones

• Non-steroid hormones are water-soluble and cannot penetrate the cell membrane.
• They bind to membrane receptors, triggering a secondary messenger (cAMP).
• cAMP activates reactions and leads to a cellular response, which activates or inhibits proteins.

Endocrine Glands

• The hypothalamus and pituitary glands
• The adrenal gland cortex
• The gonads, including testes and ovaries, are endocrine glands.

Hypothalamus

• The hypothalamus contains neurosecretory cells and is connected to the pituitary gland via the infundibulum.
• Neurosecretory cells are neurons that secrete hormones. These hormones are made in cells bodies, move along the axon, and leave from the axon ending.
• Hypothalamic neurons have a long axon, short branching dendrites, and are stored in the pituitary gland.
• Some hypothalamus hormones are stored in the pituitary, while others regulate pituitary activity.
• It produces other hormones and regulates the activity of the pituitary gland.
• ADH and oxytocin are stored in posterior pituitary axon endings.

Pituitary Gland

• The pituitary gland is connected to the hypothalamus by the infundibulum and has anterior and posterior lobes.
• Lobes secrete hormones responding to the hypothalamus.
• The pituitary lobes are located at the base of the hypothalamus.
• The anterior pituitary is glandular tissue that makes and secretes hormones.
• The posterior pituitary is nervous tissue that extends from the hypothalamus and stores hormones.
• Oxytocin, prolactin, and gonadotropins (FSH & LH) are hormone groups.
• Oxytocin is made in the hypothalamus and stored in the posterior pituitary.
• Prolactin, FSH, and LH are secreted by the anterior pituitary.
• Oxytocin causes uterine/mammary gland contraction.
• Prolactin leads to milk production.
• FSH stimulates sperm/ova production, and LH stimulates ovaries/testes.

Hypothalamus Regulation of Pituitary

• Posterior lobe mechanism: Hypothalamus neurons synthesize ADH & oxytocin.
• Hormones travel down axons, stored in the posterior pituitary, and nerve impulses trigger their release into the blood.
• Hormones move into circulation.
• Anterior lobe mechanism: Hypothalamus neurons produce releasing/inhibiting hormones that access hypothalamus capillaries.
• The bloodstream transports them to the anterior pituitary, anterior pituitary cells secrete new hormones, and these hormones enter circulation and act on the target cells.

Adrenal Gland

• Two adrenal glands are located adjacent to the kidneys.
• The adrenal cortex is the outer portion, and the adrenal medulla is the inner portion.
• The adrenal gland secretes cortisol, epinephrine, norepinephrine, corticosteroids (glucocorticoids, mineralocorticoids), and androgens (sex hormones converted to testosterone/estrogen).

Gonads

• Gonads include the ovaries and testes.
• The hormones secreted are testosterone, estrogens, and progestins (progesterone).
• Sex hormones affect growth and development, regulate reproductive cycles, and affect sexual behavior.
• Gonadotropins (FSH & LH) regulate gonads.
• Testosterone supports sperm formation and promotes male characteristics, regulated by FSH & LH.
• Estrogens support egg maturation, stimulate uterine lining growth, and promote female characteristics, regulated by FSH & LH.
• Progestins promote uterine lining growth, regulated by FSH and LH.

Male Reproductive System: Functions

• The male reproductive system produces and maintains sperm and transports sperm and associated fluids outside the body.
• It produces and secretes male sex hormones.

Male Reproductive System: Major Components

• The components of the male reproductive system include a pair of testes, ducts for sperm travel, the penis, and accessory glands.

Male Reproductive Organs and Functions

• Testis: Produces sperm and testosterone.
• Epididymis: Stores and matures sperm.
• Ductus (vas) deferens: Transports sperm from the epididymis to the urethra.
• Urethra: Transports semen during ejaculation and urine at other times.
• Seminal vesicle: Produces fluid that nourishes sperm, thickens semen, and assists sperm movement.
• Prostate gland: Produces alkaline secretions that activate sperm and reduce acidity.
• Bulbourethral gland: Produces mucus secretion that neutralizes acidic urine in the urethra.
• Penis: Delivers sperm to the female reproductive tract.

Sperm Movement

• Sperm movement through male reproductive system is: Testis → Epididymis → Ductus (vas) deferens → Urethra.

Main Tissue Types

• Epithelial tissue lines ducts, produces sperm cells in seminiferous tubules, and produces secretions in glands.
• Connective tissue makes up walls of testes and erectile cylinders.
• Nervous tissue is penis sensory nerve fibers, hypothalamus secretes hormones.
• Muscle tissue (smooth) propels sperm out.

Testes and Scrotum

• The scrotum helps regulate temperature, because testes need to be at about 35°C for sperm production.
• The left testicle usually descends lower to prevent compression.

Testes and Associated Structures

• Tunica Albuginea: Encases the testis.
• Lobules and Septa: Divide testes into lobules.
• Seminiferous Tubules: Sperm are produced here.
• Epididymis: Sperm are stored here.
• Vas Deferens: Transports sperm to the urethra.

Testes Structure

• Seminiferous Tubules: Sperm are produced.
• Leydig cells (interstitial cells): Located outside tubules; produce testosterone.
• Sertoli cells: Located inside tubules; protect and promote sperm development; secrete androgen-binding protein.
• Lumen: Inner fluid-filled space of seminiferous tubule.
• Tight Junctions between Sertoli Cells: Prevent sperm from leaving tubules and prevent damaging materials from entering.

Testes and Spermatogenesis

• General process and location: Sperm production (spermatogenesis) happens in seminiferous tubules.
• Cells are Sperm cells produced during spermatogenesis.
• Sertoli cells protect and promote sperm development.
• Leydig cells produce testosterone.
• During meiosis, chromosome reduction occurs to form secondary spermatocytes (DNA is reduced by half).
• Sequence of development: Spermatogonia → primary spermatocytes → secondary spermatocytes → spermatids → spermatozoa (mature sperm cells)

Sperm Structure

• Regions of a mature sperm cell: Head, midpiece, and tail.
• Head:
  • Acrosome: Sac covers nucleus and contains digestive enzymes for fertilization.
  • Nucleus: Contains father's chromosomes (DNA).
• Midpiece: Contains mitochondria that produce ATP.
• Tail: Flagellum that propels sperm.

Sperm Release Pathway

• Spermatogenesis occurs in the seminiferous tubules.
• Sperm migrate from the seminiferous tubules to the epididymis where they mature and are stored.
• Mature sperm travel from the epididymis into the vas deferens.
• Smooth muscle contractions of the walls of the vas deferens propel the sperm towards the urethra.
• During ejaculation, the erectile tissue of the penis fills with blood and the penis becomes erect.
• Semen is ejaculated through the end of the urethra.

Spermatic Ducts

• Seminiferous tubules are located in the testes, and cause sperm formation (spermatogenesis)
• Efferent ductules location. Connect seminiferous tubules to epididymis. Function: Collect sperm from seminiferous tubules and transport sperm to the epididymis. Cilia create a current to move sperm with about 12 small ciliated ducts.
• Eipididymis location: Posterior of testis, and is a site of sperm maturation.
• Sperm is stored in the epididymis, which provides fluids and molecules needed for sperm to mature as they slowly migrate through it.
• The Epididymis is 6 meters (20 feet) long. Sperm maturation causes them to become motile and acquire the ability to recognize and fertilize an egg. Contractions of the smooth muscle surrounding the epididymis duct aid movement. Pressure from fluid and sperm helps.
• Vas deferens: Muscular tube passing from epididymis to posterior surface of the urinary bladder​
• Function:​ Transports sperm via smooth muscle contractions
• Length: 45 cm long​
• Ends: Unites with the duct of the seminal vesicle to form the ejaculatory duct​
• Ejaculatory duct: Passes through the prostate gland​
• Function: Empties into urethra​
• Length: 2 cm long​
• Formed from the union of: The vas deferens and the seminal vesicle​
• Male Urethra: Extends through the penis
• Is shared by the reproductive and urinary systems and conveys urine and sperm
• Length: 18 cm long
• Three regions and : Prostatic, membranous, and Spongy (penile)​

Three Sets of Glands

• Seminal vesicles​ are located in a pair of glands posterior to the bladder, attached to the vas deferens.
• They secrete alkaline fluid with fructose and prostaglandins empties into the ejaculatory duct.
• Fluid is Alkaline, functions contribute to semen, alkaline pH protects sperm from the acidic environment, and percentage of semen is 60%.
• Prostate glands which surround the urethra and ejaculatory duct just inferior to the bladder
• Secretes a thin, milky, alkaline fluid that forms 30% of semen.
• Fluid is thin, milky and alkaline, which activates sperm and reduces acidity of male and female reproductive tracts, keeping sperm alive.
• Bulbourethral (Cowper) glands are located in the pair of glands near the bulb of the penis
• They produce a clear slippery fluid during sexual arousal that lubricates the head of the penis preparing for intercourse.
• It passes through the urethra before sperm, protecting sperm by neutralizing the acidity of residual urine.

Semen

• Fluid passes through the urethra to the outside during ejaculation (seminal fluid).​
• Mls per ejaculation: 2-5 ml​
• Average number of sperm per ml: 120 million​
• Sperm cells, secretions made from Seminal vesicles, prostate gland, and bulbourethral glands​
• Sperm cells function in fertilization and there are gland's secretions that provide nutrients and protect sperm.​

Prostaglandins functions

• Contraction and relaxation of smooth muscle,​ Dilation and constriction of blood vessels, control of blood pressure,​Modulation of inflammation
• Semen is alkaline to neutralize the acidity of the male and female reproductive tracts to keep sperm alive.​

Penis

• Structures include three tissues
• Cylindrical bodies of erectile tissue with Corpora cavernosa​ and Corpus spongiosum​ with sponges
• Structure of erectile tissue: Sponge-like, has many blood sinuses
• An erection happens with erectile tissue is filled with blood and is the base of the penis. The urethra flows through the penis.​

Vasectomy

• Sperm can not reach the urethra.
• Testes continue to work normally to produce sperm, all seminal fluids continue to produce, and sperm is resorbed.

Why mitochondrial DNA is maternal

• Sperm mitochondria is used destroy during fertilization so zygote mitochondria is inherited from the egg.​ Lowering sperm counts can be plastics in the environment, and viagra which was created as a cardiac meditation that dilates blood vessels which allows more bloodflow into the penis.

Regulation of the Male Reproductive System

• GnRH are secreted from the hypothalamus to stimulate secretion of LH/FSH production
• LH/FSH stimulates the support production of sperm cell production/
• Testosterone can stimulate the development of of male characteristics in males.

Regulation with Negative Feedback loops

• Regulates testosterone with Hypothalamus (GnRh), anterior pituitary gland (LH) and Testes which all cause the hypotthalmus to cause GNRH which secrete into the pituitary to send LH to the testes so the levels of GNRH gets inhibited LH, FSh and ABP which helps the sertoli cells secrete ABP that connects with the Sertoli and inhibits FSH and GNrh release, thus decreasing levels.

Female Repro Overview

Functions of the F repro are to produce and maintain egg, transport egg into fertilzation for implantation, and produce sex hormones to give birth to egg and the Female hormone sections are on a cycle.

Primarly organ is Ovaries

• Which is used to produce an estrogen for oogenesis. The Accesorry gland is organs internal and External.

Structure

• Inclusde Utuerus:Pear shaped that nurtures baby.

  • Has 3 layers: Periemtrium connective, Mymoetriym Muscle(Labour), and Edometrium inner Epithelial Layer. Tubes Cila that takes egg to Cila for fertilzation

• Vagina

  • Receptical of penis which help functions of Discharge

Hormone Overview

The ovaries produces hormones with different structures in tunica and medulla inside lymph that produces a ligament to anchor the walls, utuerus and tubes. Function of discharge: Sperm and child. with different child.