Human Anatomy and Physiology II — B.Pharmacy 2nd Semester
HAP-II continues the study of the human body, focusing on the nervous system, endocrine system, reproductive system, and special senses. This knowledge is crucial for understanding drug targets and therapeutic interventions.
Unit 1: Nervous System
The nervous system is the body’s primary control and communication system. It consists of the Central Nervous System (CNS — brain and spinal cord) and the Peripheral Nervous System (PNS — cranial and spinal nerves).
Neuron Structure
Neurons are the functional units of the nervous system, consisting of a cell body (soma), dendrites (receiving processes), and an axon (transmitting process). Axons may be myelinated (faster conduction) or unmyelinated.
Synaptic Transmission
When an action potential reaches the axon terminal, it triggers the release of neurotransmitters (acetylcholine, norepinephrine, dopamine, serotonin, GABA) into the synaptic cleft. These bind to receptors on the postsynaptic membrane, producing an excitatory or inhibitory response. This is the basis for many drug mechanisms.
Autonomic Nervous System
The ANS controls involuntary functions and is divided into:
- Sympathetic division: “Fight or flight” — increases heart rate, dilates pupils, bronchodilation
- Parasympathetic division: “Rest and digest” — decreases heart rate, stimulates digestion
Unit 2: Endocrine System
The endocrine system uses hormones as chemical messengers, secreted by ductless glands into the bloodstream to regulate metabolism, growth, reproduction, and homeostasis.
Major Endocrine Glands and Hormones
- Hypothalamus: Releasing and inhibiting hormones (TRH, GnRH, CRH)
- Pituitary (anterior): GH, TSH, ACTH, FSH, LH, Prolactin
- Pituitary (posterior): ADH (vasopressin), Oxytocin
- Thyroid: T3, T4 (metabolism), Calcitonin (calcium regulation)
- Parathyroid: PTH (increases blood calcium)
- Adrenal cortex: Cortisol, aldosterone, androgens
- Adrenal medulla: Epinephrine, norepinephrine
- Pancreas (islets of Langerhans): Insulin (beta cells), glucagon (alpha cells)
Unit 3: Reproductive System
Male Reproductive System
Consists of testes (spermatogenesis, testosterone production), epididymis, vas deferens, seminal vesicles, prostate gland, and penis. Spermatogenesis occurs in the seminiferous tubules and takes approximately 64 days.
Female Reproductive System
Consists of ovaries (oogenesis, estrogen and progesterone production), fallopian tubes, uterus, and vagina. The menstrual cycle averages 28 days and is regulated by FSH, LH, estrogen, and progesterone.
Unit 4: Urinary System
The kidneys filter approximately 180 liters of blood daily, producing about 1.5 liters of urine. Each kidney contains approximately 1 million nephrons — the functional units responsible for filtration, reabsorption, and secretion.
Urine Formation
- Glomerular filtration: Blood plasma filtered through glomerular capillaries into Bowman’s capsule (GFR ≈ 125 mL/min)
- Tubular reabsorption: ~99% of filtrate reabsorbed in PCT, loop of Henle, and DCT
- Tubular secretion: Additional substances secreted from blood into tubular fluid
Unit 5: Special Senses
Eye (Vision)
The eye is a complex optical instrument. Light enters through the cornea, passes through the pupil (controlled by the iris), is focused by the lens onto the retina, where photoreceptors (rods and cones) convert light to neural signals.
Ear (Hearing and Balance)
The ear has three parts: external ear (pinna, ear canal), middle ear (ossicles — malleus, incus, stapes), and inner ear (cochlea for hearing, vestibular apparatus for balance).
Important Exam Questions
- Describe the structure and function of a neuron
- Explain synaptic transmission with a diagram
- Differentiate between sympathetic and parasympathetic nervous systems
- Write about the hormones of the pituitary gland
- Explain the process of urine formation
- Describe the menstrual cycle with hormonal regulation