A&P test 4

body water content

- Average adult: 40L total body water (≈60% of body weight)

- Water is #1 component in body

infant water content

70% water

adult male water content

60%

Body Water Content Average adult:

40L total body water (≈60% of body weight); Water is #1 component in body

Infants water content

: ~70% water (highest content)

Adult males water content

: ~60% water

Adult females water content

: ~50% water

Elderly (50+) water content

: ~50-55% water

Muscle tissue: water content

75% water;

Fat tissue water content

: lowest water content

Fluid Compartments

(42L total)

ICF (Intracellular Fluid):

~67% (2/3) - fluid inside all cells

ECF (Extracellular Fluid):

33% (1/3) - fluid outside cells

ECF Subdivisions

Plasma: 3-5L (fluid in blood/cardiovascular system); Interstitial Fluid (IF): 10-11L (fluid between cells and tissues); Includes lymph, cerebrospinal fluid, aqueous humor, joint fluid, GI secretions

Non-electrolytes:

Organic molecules (contain carbon), no electrical charge; Examples: glucose, fats, urea, creatinine; Low osmotic power (weak at controlling fluid movement)

Electrolytes:

Carry electrical charge, break apart in water; Greater osmotic power; Main influence on fluid movement between compartments

ECF (blood/interstitial):

High Na+ and Cl- (table salt)

ICF (inside cells):

High K+ (potassium) and HPO4- (hydrogen phosphate)

Pedialyte composition mirrors body needs:

water + sodium + chloride + potassium

Osmosis:

Water movement from low to high solute concentration

Osmolarity:

Total solute concentration in solution

Tonicity:

Solution's ability to modify cell volume

Hypertonic:

High ECF solutes → water moves to ECF → cells shrink

Hypotonic:

Low ECF solutes → water moves to ICF → cells swell

Isotonic: Equal solutes →

no net water movement (normal body state)

Most IV solutions are

isotonic (0.9% saline) to match blood salt concentration

Kidney Regulation

Primary organ system regulating fluid, electrolyte, and pH balance; 60% of water loss occurs through urine; Target system for controlling water output when dehydrated

Thirst Mechanism Trigger:

Increased ECF osmolarity (high salt)

thirst mechanism Detection:

Hypothalamus

thirst mechanism Response:

Drink fluids to restore balance

ADH (Antidiuretic Hormone)

Source: Posterior pituitary

ADH Function:

Water reabsorption in kidney collecting ducts

ADH Trigger:

Same as thirst - elevated ECF osmolarity/high sodium

ADH:

Main hormone controlling fluid balance between compartment

ADH causes

oliguria - very infrequent urination

Main trigger:

increased extracellular fluid osmolarity, primarily sodium concentration

High salt diet →

increased ADH levels → water retention

Sodium Regulation

Sodium is most abundant cation in ECF - controls water movement in body

Changes in sodium affect:

blood volume, blood pressure, ECF volume, ICF levels

Renin-Angiotensin System:

Low sodium → renin release → aldosterone → increased sodium reabsorption

Aldosterone effect for sodium

Increases sodium in the body

ANP (Atrial Natriuretic Peptide):

Decreases sodium absorption → lowers blood pressure

Hypernatremia:

High blood sodium

Hyponatremia:

Low blood sodium

Hyperkalemia:

High blood potassium

Hypokalemia:

Low blood potassium

Potassium Regulation

Regulated at distal convoluted tubule via secretion (step 3 of urine formation)

Aldosterone regulates

both sodium and potassium - balancing act

Main trigger of aldosterone:

plasma potassium concentration

Calcium Regulation

PTH raises blood calcium through bone breakdown, kidney reabsorption, intestinal absorption; Calcitonin lowers blood calcium - exact opposite of PTH

Arterial blood PH:

7.4 (±0.05)

Venous blood PH

7.35 (more acidic due to CO₂)

Intracellular fluid PH

: ~7.0

Alkalosis: Arterial pH

> 7.45

Acidosis: Arterial pH

< 7.35

1. Chemical buffer systems

(seconds) - bicarbonate, phosphate, protein

2. Respiratory centers

(minutes) - brain stem controls breathing patterns

3. Renal mechanisms

(hours/days) - most potent but slowest

Bicarbonate buffer:

Best for blood/ECF

Phosphate buffer:

Best for intracellular fluid

High CO₂

→ acidic pH → increased respiratory rate

Low CO₂

→ alkaline pH → decreased respiratory rate

Kidney pH Regulation

Location: Collecting ducts with Type A and Type B intercalated cells

Type A cells (acidosis):

Excrete H⁺, reabsorb HCO₃⁻

Type B cells (alkalosis):

Excrete HCO₃⁻, reabsorb H⁺

Respiratory Acidosis:

CO₂ buildup, common in lung diseases (pneumonia, COPD, emphysema)

Respiratory Alkalosis:

Low CO₂ from hyperventilation, treat with paper bag

Metabolic Acidosis:

Low bicarbonate, causes include alcohol, diarrhea, diabetes, starvation

Metabolic Alkalosis:

High bicarbonate causing elevated pH; Usually indicates kidney problems since kidneys regulate bicarbonate

Erectile tissue

makes penis stiff to perform function

Two types of erectile tissue:

Corpus cavernosa (top, doesn't extend to tip) and Corpus spongiosum (surrounds urethra, extends to tip)

Blood flow mechanism for erectile tissue:

Arteries open up, blood enters tissue, veins block exit creating erection

Male Duct System Pathway

Testes → Epididymis → Vas Deferens → Ejaculatory Duct → Urethra

Epididymis:

C-shaped structure, stores sperm for ~30 days, allows maturation

Vas Deferens:

45cm long tube carrying sperm from epididymis

Seminal glands:

Make 70% of semen volume, alkaline seminal fluid

Prostate:

Encircles urethra, makes 25-30% of semen, milky white fluid

Bulbourethral glands:

Small, neutralize acidic urine in urethra

Scrotum location:

Outside body for 3°C lower temperature needed for sperm production

Muscle control:

Dartos and cremaster muscles regulate testicle proximity to body

Location of sperm production:

Seminiferous tubules in testicles only

Process of sperm production:

Spermatogonia → Primary spermatocyte → Secondary spermatocytes → 4 spermatozoa

Duration of sperm production

: ~2 months from start to finish

Chromosome reduction:

46 → 23 chromosomes through meiosis

HPG Axis:

Hypothalamus releases GnRH → Pituitary releases FSH/LH → Testosterone production

Testosterone effects:

Triggers spermatogenesis, secondary sex characteristics, sexual maturation

Vasectomy:

Surgical cutting of vas deferens, 100% effective but reversible

Prostate cancer:

#2 cause of death in males after lung cancer

ED treatment:

Viagra/Cialis increase blood flow as vasodilators

Gonads:

Two ovaries that produce ova (eggs) and hormones (estrogen, progesterone)

Pathway

: Ovary → Fallopian tube → Uterus → Cervix → Vagina

Internal genitalia:

Duct system (fallopian tubes, uterus, vagina)

External genitalia:

Vulva (external covering)

Histology of ovary:

White color from tunica albuginea (connective tissue capsule)

Cortex of ovary:

Contains follicles (rounded structures housing eggs)

Medulla of ovary:

Contains blood supply (ovarian arteries/veins)

Follicles:

Small circular sacs filled with fluid, each containing an oocyte (immature egg)

Primordial follicles:

Small, single-layered with primary oocyte (1.5 million at birth)

Primary follicles:

Develop during puberty, contain primary oocyte in meiosis I

Secondary follicles:

Larger with multiple cell layers, contain secondary oocyte