SCIENCE THIRD QUARTER EXAM

• Impotence can result from:

  • Consumption of alcohol and other drugs
  • Emotional, nervous system, or circulatory problems
  • Treatment includes drugs and penile implant devices
  • Viagra acts by promoting the action of nitric oxide
• Testes are the male gonads

  • Consists of many highly coiled seminiferous tubules surrounded by layers of connective tissue
  • Sperm form in seminiferous tubules
• Urethra:

  • Extends from the base of the urinary bladder to the tip of the penis
  • Carries both urine and sperm
  • Sperm enters from the ejaculatory duct
• Testes are located in the scrotum, outside the body cavity

  • The testes develop in the body cavity and descend into the scrotum just before birth
  • Sperm pass from the seminiferous tubules to the coiled tubules of the epididymis
  • In the epididymis, sperm become motile and gain the ability to fertilize
• Seminal fluid contains:

  • Mucus, fructose, a coagulating enzyme, ascorbic acid, and prostaglandins
  • Accessory glands include the seminal vesicle, prostate gland, and bulbourethral gland
• Ejaculation:

  • Propels sperm from the epididymis to the vas deferens
• Mature Spermatozoa consist of:

  • Tail, mitochondria, nucleus, acrosome, and head
  • Emission involves muscle contractions closing the sphincter at the base of the bladder
  • Ejaculation is a sympathetic nervous system reflex
• Hormones Involved in Spermatogenesis:

  • Gonadotropin Releasing Hormone (GnRH)
  • Follicle Stimulating Hormone (FSH)
  • Interstitial Cell Stimulating Hormone (ICSH), also called LH
  • Testosterone
  • Inhibin
• Some Other Effects of Testosterone:

  • Muscle and bone growth
  • Facial and pubic hair growth
  • Thickening of vocal cords
  • Stimulates reproductive organ development
  • Underlies sex drive
  • Secondary sex characteristics
• Hormones are chemical messengers secreted by a gland that affect a specific target tissue or organ
• Chemical control, regulated by the Endocrine system, includes various hormones
• Chemical control is slow-acting but has a long-term effect
• Nervous control, regulated by the Nervous System, is fast-acting with short-term effects
• The nervous system is an organ system designed to sense the environment and produce a response to changing conditions
• Neurons are the basic structural and functional unit of the nervous system
• Neurons conduct impulses and are made up of dendrites, cell body, and an axon
• Once stimulated, a neuron transmits electrical signals called an action potential or an impulse
• Neurons have three types: Sensory Neurons, Interneurons, and Motor Neurons
• Sensory Neurons carry impulses from inside and outside the body to the brain and spinal cord
• Interneurons are found within the brain and spinal cord, processing incoming impulses and passing them on to motor neurons
• Motor Neurons (efferent neurons) carry impulses away from the brain and spinal cord
• The Central Nervous System consists of the brain and spinal cord
• The CNS acts as the body's control center, coordinates activities, stores memory, and carries out thought
• The Peripheral Nervous System is made up of all nerves that carry messages to and from the CNS
• The PNS includes the Somatic Nervous System and the Autonomic Nervous System
• The Somatic Nervous System relays information between skin, skeletal muscles, and the central nervous system
• Somatic Nervous System allows conscious control over muscle movements, except for reflexes
• The Autonomic Nervous System relays information from the CNS to organs and is involuntary
• The Autonomic Nervous System includes the Sympathetic and Parasympathetic Divisions
• The Sympathetic Division produces the "fight or flight" response, while the Parasympathetic Division produces the "rest and ruminate" response
• Endocrine Glands are the organs of the Endocrine System that produce and secrete (release) Hormones
• Endocrine Glands are the organs of the Endocrine System that produce and secrete (release) Hormones
• Hormones are chemical messengers that are secreted (released) from glands into the blood and affect cells in another part of the body
• Negative feedback in hormone control means that when enough hormone is in the body, the body stops producing the hormone until it is needed again
• Positive feedback systems in hormone control involve the pituitary gland sending oxytocin to the uterus causing contractions, leading to more oxytocin release until birth occurs
• External structure of the penis:

  • The shaft of the penis
  • The glans penis
  • The glans
• • The shaft of the penis is covered by relatively thick skin
• • The glans penis is covered by thinner skin
• • The glans is covered by the prepuce which may be removed by circumcision
• • There is no verifiable health benefit to circumcision