Urinary System & Water/Electrolyte Balance

Overview of the Urinary System

The urinary system is responsible for filtering blood, removing waste, and regulating water and electrolyte balance. It consists of organs such as the kidneys, ureters, bladder, and urethra.

• Key Structures: Kidneys, nephrons, ureters, bladder, urethra

• Nephron: The functional unit of the kidney, responsible for filtration and urine formation

• Filtration: Occurs from renal corpuscle to ureter

• Glomerular Filtration Rate (GFR): Measures kidney function; factors include blood pressure and permeability

• Blood Supply: Afferent and efferent arterioles regulate filtration pressure

• Electrolyte Regulation: Kidneys maintain homeostasis of ions such as Na+, K+, and Cl-

Example: If blood sodium levels are high, the kidneys excrete more sodium to restore balance.

Reproductive System

Structure and Function

The reproductive system enables the production of offspring and includes organs for gamete production and hormone secretion.

• Female Structures: Ovaries, fallopian tubes, uterus, vagina

• Male Structures: Testes, epididymis, vas deferens, prostate, penis

• Gamete Production: Oogenesis (egg formation) and spermatogenesis (sperm formation)

• Hormonal Regulation: Hypothalamus and pituitary hormones control reproductive cycles

• Primary Sex Characteristics: Organs directly involved in reproduction

• Secondary Sex Characteristics: Features such as body hair, breast development, and voice changes

Example: Estrogen and testosterone are key hormones influencing secondary sex characteristics.

Pregnancy, Growth, and Development

Stages and Processes

This topic covers fertilization, embryonic development, and fetal growth.

• Fertilization: Fusion of sperm and secondary oocyte

• Prenatal Periods: Embryonic and fetal stages

• Development: Zygote to blastocyst, then embryo and fetus

• Layers of Blastocyst: Trophoblast and inner cell mass

Example: The blastocyst implants in the uterine wall to begin pregnancy.

Endocrine System

Hormones and Glands

The endocrine system regulates body functions through hormones secreted by glands.

• Major Glands: Pituitary, thyroid, adrenal, pancreas, gonads

• Target Cells: Cells with specific receptors for hormones

• Hormone Transport: Via bloodstream to target tissues

• Feedback Mechanisms: Negative and positive feedback regulate hormone levels

• Homeostasis: Endocrine and nervous systems work together

• Pancreatic Hormones: Insulin and glucagon regulate blood glucose

Example: ADH (antidiuretic hormone) controls water reabsorption in kidneys.

Blood

Composition and Function

Blood is a connective tissue that transports nutrients, gases, and waste, and plays a role in immunity.

• Plasma Proteins: Albumin, globulins, fibrinogen

• Formed Elements: Erythrocytes (RBCs), leukocytes (WBCs), platelets

• Leukocyte Types: Neutrophils, lymphocytes, monocytes, eosinophils, basophils

• Hemoglobin: Oxygen-carrying protein in RBCs

• Blood Types: Determined by antigens and antibodies

• pH Range: 7.35–7.45

Example: Type O blood has no A or B antigens, making it a universal donor.

Cardiovascular System

Heart and Blood Vessels

The cardiovascular system circulates blood throughout the body, delivering oxygen and nutrients.

• Heart Structures: Chambers, valves, septa, chordae tendineae

• Cardiac Cycle: Systole (contraction) and diastole (relaxation)

• Electrical Conduction: SA node, AV node, bundle branches, Purkinje fibers

• Blood Vessels: Arteries, veins, capillaries

• Blood Pressure: Systolic/diastolic, measured in mmHg

Example: The QRS complex on an ECG represents ventricular depolarization.

Lymphatic System

Immunity and Fluid Balance

The lymphatic system returns excess fluid to the bloodstream and defends against pathogens.

• Lymph Nodes: Filter lymph and house immune cells

• Lymph Vessels: Transport lymph fluid

• Thymus: Site of T cell maturation

• Spleen: Filters blood and removes old RBCs

• Innate vs. Adaptive Immunity: Innate is non-specific; adaptive is specific and has memory

Example: B cells produce antibodies as part of adaptive immunity.

Respiratory System

Gas Exchange and Airway Structures

The respiratory system supplies oxygen to the body and removes carbon dioxide.

• Major Structures: Nasal cavity, pharynx, larynx, trachea, bronchi, lungs

• Respiratory Volumes: TV (tidal volume), ERV (expiratory reserve), IRV (inspiratory reserve), RV (residual volume), TLC (total lung capacity)

• Control of Breathing: Medulla oblongata and pons regulate rate and depth

• Gas Exchange: Occurs in alveoli via diffusion

• Protective Mechanisms: Mucus, cilia, immune cells

Example: High CO2 levels stimulate increased breathing rate.

Digestive System

Digestion and Absorption

The digestive system breaks down food, absorbs nutrients, and eliminates waste.

• Main Organs: Mouth, esophagus, stomach, small intestine, large intestine

• Digestive Juices: Saliva, gastric juice, pancreatic juice, bile

• Enzymes: Amylase (carbohydrates), protease (proteins), lipase (fats), nuclease (nucleic acids)

• Segmentation vs. Peristalsis: Segmentation mixes; peristalsis propels food

• Protective Mechanisms: Mucus lining, immune cells

• Vitamin B12: Essential for RBC formation; absorbed in the ileum

Example: Jaundice occurs when bilirubin accumulates due to liver dysfunction.

Table: Blood Cell Types and Functions

Key Equations

• Glomerular Filtration Rate (GFR):

• Blood Pressure:

• Oxygen Transport (Hemoglobin):

• Respiratory Volumes:

Additional info: Academic context and definitions have been expanded for clarity and completeness. Table entries and equations are inferred from standard Anatomy & Physiology curriculum.