Lecture Notes: Male Reproductive System - Ejaculation Physiology

Introduction

Sensory Components:
- Tactile sensation: Touch related to reproductive organs
- Neural mechanisms: Psychological aspects from the forebrain to spinal cord
Pathway:
- Tactile information sent via pudendal and sacral nerves to the spinal cord
- Information synapses in spinal cord nuclei, possibly sent to the hypothalamus
- Hypothalamus controls autonomic functions (parasympathetic and sympathetic)
Parasympathetic Mechanism:
- Inhibits smooth muscle contraction at the base of the penis
- Allows blood flow into erectile tissues, causing erection

Sympathetic Mechanisms:
- Required for ejaculation
- Transition from parasympathetic (relaxed state) to sympathetic response
- Too much excitement can hinder erection due to sympathetic dominance
Process:
- Sympathetic stimulation post-erection triggers smooth muscle contraction
- Contraction occurs in arteries, glandular tissues (prostate, seminal vesicles, vulvo-urethral glands)
- Major component: Epididymis contraction moves sperm to vas deferens
- Peristaltic waves in vas deferens assist sperm movement to urethra

Glandular Contributions:
- Secretions from bulbo-urethral glands, prostate, seminal vesicles added to urethra
- Secretions precede sperm entry into urethra
Orgasm and Ejaculation:
- Culmination of sympathetic activity
- Contraction of epididymis and peristaltic waves facilitate sperm movement
- Results in ejaculation

Resolution Phase:
- Vasoconstriction reduces blood flow to the penis
- Blood seeping out through dorsal vein decreases pressure
- Leads to relaxation of the penis

Spinal cord coordinates erection and ejaculation by communicating with brain and autonomic pathways
Upcoming lectures to focus on glandular tissues and their roles

Note: This lecture is part of a series on the male reproductive system, focusing on anatomy, physiology, and hormonal mechanisms.