Fluid, Electrolyte, & Reproductive System Overview
Fluid, Electrolyte, & Acid-Base Balance:
- Body fluids: Our bodies are mostly water, with men being approximately 60% water and women around 55% water. 2
- Fluid compartments: Body fluids are divided into three compartments: Intracellular fluid (2/3) and Extracellular fluid (1/3), which includes Blood plasma and Interstitial fluid. 3
- Fluid movement: Fluid moves through pressure differentials. 4
Osmosis is the movement of water, while hydrostatic pressure is similar to a leaky garden hose (found in blood vessels). 5
Osmotic pressure is the force that draws water to areas with high solute concentration. 6 - Water intake & output: The body regulates water intake and output to maintain stable extracellular fluid (ECF) osmolality. 7
Water is obtained through food, fluids, and a small amount from cellular respiration. 8
Water leaves the body through urine, sweat, feces, and exhaled air. 9 - Electrolyte regulation: Electrolytes, such as sodium, potassium, calcium, and phosphate, are important for various bodily functions. 10
Sodium, in particular, affects osmotic flow and is linked to extracellular fluid volume and blood pressure regulation. 11 - Acid-Base balance: Chemical buffers and respiratory regulation help maintain short-term acid-base balance. 12
Chemical buffers, such as bicarbonate, phosphate, and protein, neutralize strong acids or bases that enter the bloodstream. 13
Respiratory regulation involves the bicarbonate buffer system and adjustments in breathing patterns to regulate carbon dioxide levels. 14 - Consequences of imbalance: Inability to regulate water balance can lead to dehydration (cell shrinkage), overhydration/hypotonic hydration (cell swelling and bursting), and edema (excess fluid in the interstitial space). 15
Electrolyte imbalances can cause neurological and muscular system dysfunction. 16
pH imbalances can result in respiratory or metabolic acidosis or alkalosis, leading to dysfunction in all organ systems. 17 Reproductive System:
- Goal: The reproductive system’s overall goal is to produce offspring. 18
This requires the production of male gametes (sperm) and female gametes (ova) by the male and female gonads. 18
- Male reproductive system anatomy: The male reproductive system includes the scrotum, which contains the testes. 19
The testes produce sperm in the seminiferous tubules. 20
The epididymis houses and matures the sperm. 21
The vas deferens conducts sperm from the epididymis to the urethra. 22
The urethra carries sperm out of the penis. 24
Accessory glands, such as the seminal glands, prostate, and bulb-urethral glands, produce fluids that make up the bulk of semen. 25 - Male reproductive physiology: The male sexual response involves erection and ejaculation. 26
Erection is initiated by parasympathetic reflexes, which dilate arterioles in penile spongy tissue, causing the penis to fill with blood. 27
Ejaculation occurs as part of the male orgasm, with contractions in various reproductive structures expelling semen. 28
Spermatogenesis is the process of creating sperm cells, regulated by the hypothalamic-pituitary-gonadal (HPG) axis. 29 - Female reproductive anatomy: The female reproductive system includes the ovaries, fallopian tubes, uterus, vagina, external genitalia, and mammary glands. 30
The ovaries produce ova and sex hormones. 31
The fallopian tubes conduct the egg towards the uterus. 32
The uterus is a muscly organ that houses the developing embryo/fetus. 33
The vagina serves as the copulatory organ and a canal for menstrual flow or childbirth. 34
The mammary glands produce milk. 35 - Female reproductive physiology: Oogenesis is the process of forming ova. 36
It starts in-utero, and at puberty, one dominant oocyte completes meiosis I each month. 37
The ovarian cycle consists of the follicular phase, ovulation, and the luteal phase. 38
The uterine cycle consists of the menstrual phase, proliferative phase, and secretory phase. 39
Both cycles are regulated by the HPG axis. 40
Development & Pregnancy:
– Fertilization: Fertilization occurs when sperm and egg chromosomes combine to form a zygote. 41
The oocyte is viable for about 1-2 days, and sperm must survive the hostile vaginal/uterine environment to reach the fallopian tube. 42
Fertilization involves the release of enzymes by sperm to penetrate the egg’s layers, followed by the fusion of sperm and egg nuclei. 43
- Embryonic development: After fertilization, the zygote undergoes cleavage, a rapid increase in the number of cells. 44
By day 7, it becomes a blastocyst. 45
The blastocyst implants into the endometrium and triggers the formation of the placenta. 46 - Gastrulation + organogenesis: Gastrulation is the process where germ layers develop. 47
The ectoderm gives rise to the nervous system and epidermis. 48
The endoderm forms the internal linings of the respiratory, digestive, and urogenital systems. 49
The mesoderm forms bones, muscles, and organ walls. 50
Organogenesis involves the differentiation of germ layers into specific organ systems. 51 - Fetal circulation: In-utero, the fetal circulation is unique. 52
The umbilical cord with its arteries and veins is active, allowing the exchange of oxygen and nutrients. 53
Structures like the ductus venosus, foramen ovale, and ductus arteriosus bypass certain circulatory pathways. After birth, these structures close or shunt, redirecting blood flow. - Pregnancy timeline: Pregnancy is divided into the embryonic period (weeks 1-8) and the fetal period (weeks 9-birth). 54
During the embryonic period, the most sensitive to teratogens, major organ systems develop. The fetal period involves continued growth and development. - Physiological changes during pregnancy: Pregnancy brings about various physiological changes. The uterus expands, causing the ribcage to flare. 55
Weight gain is necessary to provide nutrients for the developing baby. 56
The gastrointestinal system may experience nausea, vomiting, heartburn, and constipation. 57
The urinary system is affected by the pressure of the growing uterus. 58
The respiratory system adapts to meet the increased oxygen demand. 59
The cardiovascular system undergoes changes to accommodate the growing baby and increased blood supply. 60 - Parturition (labor/delivery): Parturition is the process of giving birth. 61
The baby determines its own due date through hormonal signaling. 61
Labor occurs in three stages: dilation, expulsion, and placental. 62
Hormonal changes and contractions lead to the baby’s delivery. - Lactation: After birth, lactation begins. 63
Hormonal regulation involves the release of prolactin and oxytocin. 64
Prolactin stimulates milk production, while oxytocin triggers the release of milk from the mammary glands. 64
Regular stimulation of the nipples is necessary to sustain lactation. 63