Systemic circulation (heart to body and back).

Human Excretory System:
Labeling of major organs:
- Kidneys (paired).
- Ureters (tubes from kidneys to bladder).
- Urinary Bladder.
- Urethra.
Nephron:
Detailed structure of the functional unit of the kidney:
- Bowman's Capsule: Cup-shaped structure.
- Glomerulus: Capillary network inside Bowman's capsule.
- Renal Tubule:
  - Proximal Convoluted Tubule (PCT).
  - Loop of Henle (descending and ascending limbs).
  - Distal Convoluted Tubule (DCT).
- Collecting Duct.
- Associated blood vessels (afferent/efferent arterioles, peritubular capillaries).

Neuron (Nerve Cell):
Structure showing:
- Cell Body (Soma): Contains nucleus.
- Dendrites: Receive signals.
- Axon: Transmits signals away from cell body.
- Myelin Sheath: Insulating layer.
- Nodes of Ranvier: Gaps in myelin sheath.
- Synaptic Knobs/Terminals: Endings that transmit signals to other cells.
Reflex Arc:
Diagram showing the pathway of a reflex action:
- Stimulus and Receptor.
- Sensory Neuron (afferent).
- Relay Neuron (Interneuron) in spinal cord.
- Motor Neuron (efferent).
- Effector (muscle or gland) and Response.
Human Eye:
Longitudinal section showing:
- Cornea: Transparent outer layer.
- Iris: Controls pupil size.
- Pupil: Opening in the center of the iris.
- Lens: Focuses light.
- Retina: Light-sensitive layer with photoreceptors (rods and cones).
- Optic Nerve: Transmits visual information to brain.
- Ciliary Body, Suspensory Ligaments, Vitreous Humor, Aqueous Humor, Blind Spot, Yellow Spot/Macula.
Human Ear:
Diagram showing the three main parts:
- Outer Ear: Pinna (auricle), Ear canal (auditory meatus).
- Middle Ear: Eardrum (tympanic membrane), Ossicles (malleus, incus, stapes), Eustachian tube.
- Inner Ear: Cochlea (hearing), Semicircular Canals (balance), Auditory nerve.

Human Endocrine Glands:
Location of major glands in the body:
- Pituitary Gland (base of brain).
- Thyroid Gland (neck).
- Pancreas (abdomen).
- Adrenal Glands (on top of kidneys).
- Testes (males) / Ovaries (females).

Human Reproductive System (Male):
Diagram showing:
- Testis, Epididymis, Vas deferens, Seminal vesicles, Prostate gland, Urethra, Penis.