Endocrine and Reproductive Systems Review

Endocrine System Themes

• Chemical signals or messages.

• Hormones produced in one place travel to cells sensitive to their signal.

Thyroid

• Important in regulating metabolism.

• Cellular respiration relates to metabolism because it's needed to make ATP for work and building.

• Organic compounds (containing carbon backbones) are used for energy.

• Hydrogen is selectively plucked off organic compounds to provide energy. B vitamins are involved in this process.

• Carbon dioxide (CO2) and water (H2O) are byproducts of this process, where oxygen takes two hydrogen electrons to form the water molecules.

• Thyroid hormone influences metabolism; higher metabolism leads to increased body temperature.

• Sweating is a negative feedback loop to compensate for rising body temperature during exercise, which is induced by increased ATP production and heat.

• Overactive Thyroid:

  • Causes feeling hot.

  • Ramps up heart rate.

  • Raises blood pressure due to smooth muscle contraction in the circulatory system.

  • Increases brain vigilance, potentially leading to anxiety. This can manifest as restlessness, difficulty concentrating, and irritability.

• Underactive Thyroid:

  • Causes feeling cold.

  • Slows brain function and memory. This can lead to difficulty in recalling recent events or learning new information.

  • Can cause sleepiness and lethargy. Individuals may feel tired even after adequate rest.

  • May contribute to depression due to decreased brain function. Reduced levels of thyroid hormones can affect neurotransmitter balance in the brain.

Adrenal Glands

• Located on top of the kidneys (renal).

• Main theme: Dealing with stress.

• Sympathetic Nervous System (Fight or Flight):

  • Raises heart rate and blood pressure.

  • Increases fuel levels (e.g., glucose) to enable escape from threats.

• Adrenal Medulla (Inner Part):

  • Mimics the sympathetic nervous system through the release of epinephrine (adrenaline) and norepinephrine.

  • Deals with immediate stress.

  • Epinephrine causes bronchodilation in the lungs increasing oxygen intake. It also causes vasoconstriction in the skin and gut while causing vasodilation in the muscles to allow for greater blood flow to muscles.

• Adrenal Cortex (Outer Part):

  • Deals with different types of stress through hormones like cortisol and aldosterone.

• Glucocorticoids (e.g., Cortisol):

  • Slow-acting stress response.

  • Suppresses the immune system and inflammation. Prolonged suppression can increase susceptibility to infections.

  • Raises blood glucose levels during prolonged stress, such as when starving.

  • Works similarly to glucagon in raising blood glucose levels through hydrolysis.

• Mineralocorticoids (e.g., Aldosterone):

  • Regulates fluid volume.

  • Increases sodium reabsorption in the kidneys, which attracts water and raises blood pressure.

  • Helps maintain sodium levels for action potentials to deal with distress.

Pancreas

• Unique as it functions as both an endocrine and exocrine gland.

• Endocrine Function:

  • Secretes insulin (lowers blood glucose levels). Insulin promotes the uptake of glucose into cells, converting it into glycogen for storage.

  • Secretes glucagon (raises blood glucose levels). Glucagon stimulates the liver to break down glycogen into glucose and release it into the bloodstream.

• Exocrine Function:

  • Produces hydrolytic enzymes for digestion and secretes bicarbonate to neutralize chyme acidity in the small intestine.

  • Hydrolyzes food into smaller molecules for absorption.

  • Pancreatic amylase: Aids carbohydrate breakdown.

  • Pancreatic lipase: Aids fat breakdown, working with bile for emulsification and hydrolysis.

  • Proteases: Aid protein breakdown. These enzymes are secreted in an inactive form (zymogens) to ensure they don't digest the pancreas itself.

  • Bicarbonate, produced by the pancreas, is released to neutralize the acidic condition of the stomach. The acidity in the stomach aids with denaturing/unraveling proteins so that hydrolysis (breaking the peptide bonds) can occur.

Reproductive System

Male Reproductive System

• Testes:

  • Produce sperm (spermatogenesis).

  • Produce testosterone.

• Plumbing:

  • Sperm matures in the epididymis (boot camp). During maturation, sperm gain motility and the ability to fertilize an egg.

  • Travels through the ductus deferens (vas deferens).

  • Passes accessory glands (seminal vesicle, prostate gland, bulbourethral glands) which contribute to semen.

• Prostate Gland:

  • Enlargement can affect urination due to its location near the bladder and urethra.

  • Enlargement may be benign (due to testosterone exposure) or cancerous.

• Testes Temperature Regulation:

  • Requires cooler temperature than body temperature for optimal sperm production. This is why the testes are located outside the body in the scrotum.

  • The testes disengage to increase the length of the vessel to wick heat away.

  • Cremaster muscle pulls testes closer to the body when cold/to regulate temperature.

• Sperm Structure:

  • Head with acrosome (hydrolytic enzyme for penetrating the oocyte).

  • Midpiece with mitochondria (powerhouse for ATP production powering the flagellum).

  • Tail for movement.

• Hormonal Control:

  • Anterior pituitary releases LH (luteinizing hormone) to stimulate testosterone production.

  • FSH (follicle-stimulating hormone) supports sperm maturation. Sertoli cells in the seminiferous tubules are stimulated by FSH to nourish developing sperm cells.

• Testosterone:

  • Production increases during puberty.

  • Promotes musculoskeletal growth.

  • Develops reproductive organs.

  • Enlarges the larynx (deepening the voice).

  • Increases libido.

  • Promotes hair growth.

  • Increases red blood cell production (erythropoiesis).

Female Reproductive System

• Ovaries:

  • Produce eggs (oocytes).

  • Produce estrogen and progesterone.

  • Each ovary contains thousands of follicles, each with the potential to release an egg.

• Uterine Tube (Fallopian Tube):

  • Transports the egg to the uterus. Cilia and peristaltic contractions facilitate the movement of the egg.

  • Fertilization typically occurs here.

• Uterus:

  • Site of implantation and fetal development. The uterine lining (endometrium) thickens and prepares for implantation.

• Cervix:

  • Lower part of the uterus connected to the vagina.

  • Dilates during labor.

  • The cervical mucus changes throughout the menstrual cycle, becoming thinner during ovulation to facilitate sperm passage.

• Ovaries as Endocrine Glands:

  • Stimulated by FSH and LH from the anterior pituitary.

  • Mature eggs develop in Graafian follicles. The Graafian follicle ruptures during ovulation to release the egg.

• Ovulation:

  • Egg release from the ovary.

• Estrogen:

  • Secondary sex characteristics, including more adipose tissue. Estrogen promotes fat deposition in the breasts, hips, and thighs.

  • Bone health and development which includes osteoblast activity. Estrogen increases calcium absorption in the bones, preventing osteoporosis.

• Fertilization:

  • Sperm penetrates the egg, and genetic material fuses.

  • Luteinizing hormone triggers ovulation.

  • Zygote forms and undergoes mitosis.

  • Most body cells have 46 chromosomes (2n, diploid number).

  • Sex cells (sperm and oocyte) have 23 chromosomes (haploid number).

  • Sex is determined by the sperm (X or Y chromosome).

Chemical Bonds:

• Ionic Bond: Formed when one atom steals another atom's electron(s).

• Covalent Bond: Formed when electrons are shared.

• Non-Polar Covalent Bond: Electrons are shared evenly, leading to zero charge.

• Polar Covalent Bond: Electrons are shared unevenly to cause a slight charge to the molecule.

Macromolecules and Reactions:

• Dehydration Synthesis: Assembling or building molecules by removing water.

• Hydrolysis