Anatomy & Physiology Study Guide: Urinary, Respiratory, Nervous Systems, and Special Senses

Urinary System / Kidneys

Main Concepts

The urinary system is responsible for filtering blood, removing waste, and regulating fluid and electrolyte balance. The kidneys are the primary organs involved in these processes.

• Functions of the kidneys: The kidneys filter blood, remove metabolic waste, regulate water and electrolyte balance, and maintain acid-base homeostasis.

• Structure and function of a nephron: The nephron is the functional unit of the kidney, consisting of the glomerular capsule (Bowman's capsule), proximal tubule, loop of Henle, distal tubule, and collecting duct. Each part plays a role in filtration, reabsorption, and secretion.

• Difference between filtrate and urine: Filtrate is the fluid filtered from blood in the glomerulus; urine is the final product after reabsorption and secretion in the nephron.

• Role of ADH in water regulation: Antidiuretic hormone (ADH) increases water reabsorption in the collecting ducts, concentrating urine.

• Pathway of urine formation to excretion: Urine forms in nephrons, passes through renal pelvis, ureters, bladder, and exits via the urethra.

• Kidney stones and their effect: Kidney stones are solid deposits that can obstruct urine flow and cause pain or infection.

Example: A person with diabetes insipidus has a deficiency of ADH, resulting in excessive urine output.

Respiratory System

Main Concepts

The respiratory system enables gas exchange, supplying oxygen to tissues and removing carbon dioxide. It consists of airways, lungs, and associated muscles.

• Primary function: Exchange of gases (O2 and CO2) between air and blood.

• Air pathway: Air travels through the nasal cavity, pharynx, larynx, trachea, bronchi, bronchioles, and alveoli.

• Filtration, warming, and humidification: Nasal passages filter, warm, and humidify incoming air.

• Mechanics of breathing: Involves contraction of the diaphragm and intercostal muscles. $\text{Pressure change} = \text{Volume change}$ (Boyle's Law)

• Role of surfactant: Surfactant reduces surface tension in alveoli, preventing collapse.

• Lung volumes: Includes tidal volume, vital capacity, and residual volume.

• Respiratory protection: Mucus and cilia trap and remove particles.

• Effects of smoking: Smoking damages cilia and increases risk of respiratory diseases.

• Common disorders: Asthma, chronic obstructive pulmonary disease (COPD), pneumonia.

Example: In asthma, airway inflammation leads to bronchoconstriction and difficulty breathing.

Nervous System

Main Concepts

The nervous system coordinates body activities through electrical and chemical signals. It consists of the central and peripheral nervous systems.

• Main functions: Sensory input, integration, motor output, and homeostasis.

• Neuron structure and function: Neurons have dendrites (receive signals), cell body (processes signals), axon (transmits signals), and synapse (junction for communication).

• Divisions: CNS (brain and spinal cord) and PNS (nerves outside CNS).

• PNS subdivisions: Somatic (voluntary control) and autonomic (involuntary control).

• Sympathetic vs. parasympathetic: Sympathetic prepares for 'fight or flight'; parasympathetic promotes 'rest and digest'.

• Types of neurons: Sensory (afferent), motor (efferent), interneurons (connect neurons).

• CNS protection: Includes meninges, cerebrospinal fluid, and blood-brain barrier.

• Brain regions: Hindbrain (medulla, pons, cerebellum), midbrain, forebrain (cerebrum, thalamus, hypothalamus).

• Common disorders: Multiple sclerosis, Parkinson's disease, epilepsy.

Example: In Parkinson's disease, degeneration of dopamine-producing neurons leads to motor symptoms.

Special Senses (Ear & Eye)

Hearing

The ear detects sound waves and converts them into electrical signals for the brain to interpret.

• Ear structures: Outer ear (pinna, auditory canal), middle ear (ossicles), inner ear (cochlea).

• Function of hair cells: Hair cells in the cochlea convert mechanical vibrations into nerve impulses.

Example: Damage to hair cells from loud noise can cause hearing loss.

Vision

The eye detects light and enables vision through specialized photoreceptor cells.

• Pathway of light: Light passes through cornea, lens, and is focused on the retina where photoreceptors (rods and cones) detect it.

• Function of rods and cones: Rods detect low light and peripheral vision; cones detect color and detail.

• Role of iris, cornea, and lens: Iris controls pupil size; cornea and lens focus light onto the retina.

• Common eye disorders: Myopia (nearsightedness), hyperopia (farsightedness), cataracts.

Example: In cataracts, the lens becomes cloudy, impairing vision.

System	Main Function	Key Structures	Common Disorders
Urinary	Waste removal, fluid balance	Kidneys, nephrons, ureters, bladder	Kidney stones, infections
Respiratory	Gas exchange	Lungs, trachea, bronchi, alveoli	Asthma, COPD, pneumonia
Nervous	Coordination, control	Brain, spinal cord, nerves	MS, Parkinson's, epilepsy
Special Senses	Detection of stimuli	Ear (cochlea), eye (retina)	Hearing loss, cataracts