sci rev

• Feedback mechanism in the female reproductive system


  1. Change in the level of one hormone influences the level of the other hormones

  2. Positive feedback mechanism: increase in one hormone stimulates the production of another hormone

  3. Negative feedback mechanism: increase in one hormone stops the production of another hormone
• Menstruation


  A series of changes in the female reproductive system caused by rise and fall in levels of hormones
• Menstruation may start (menarche) between ages 12-15 and end (menopause) between ages 48-50
• Menstrual cycle


  1. FSH stimulates growth of several follicles in the ovaries

  2. Dominant follicle secretes estrogen

  3. Estrogen inhibits growth of other follicles and further secretion of FSH

  4. Estrogen stimulates uterine lining (endometrium) growth
• Follicular phase


  1. An increase in estrogen stimulates LH secretion

  2. An increase in LH causes ovulation (release of mature egg cell)

  3. A ruptured follicle forms corpus luteum
• Ovulation


  1. Corpus luteum secretes estrogen and progesterone

  2. Progesterone stimulates uterine lining (endometrium) growth

  3. Estrogen and progesterone inhibits further secretion of FSH and LH

  4. Corpus luteum degrades causing progesterone level to drop
• Luteal phase


  Without progesterone, uterine lining (endometrium) cannot be maintained; thus, it detaches which leads to menstruation
• Menstruation


  1. Uterine lining (endometrium) breaks down

  2. FSH starts the cycle
• Nervous system


  Connects all body parts and transmits signals from one part to another
• Nervous system


  • Composed of cells, tissues, and organs that regulate the response of the body to internal and external stimuli
  • Responsible for coordinating all the activities of the body
  • Responsible for maintaining normal functions and ability of the body to cope with emergency situations
  • Serves sensory function, interpretative function, and motor function
• Central Nervous System (CNS)


  Serves as the main processing center for the entire nervous system
• Peripheral Nervous System (PNS)


  Connects the central nervous system to the organs and limbs
• Parts of the Central Nervous System

  • Brain
  • Spinal Cord
• Brain


  • Organ located within the skull that functions as organizer and distributor of information in the body
• Parts of the Brain

  • Cerebrum
  • Cerebellum
  • Brainstem
• Cerebrum


  Large, upper part of the brain that serves as the center for thought and intelligence
• Cerebrum


  • Responsible for speech, hearing, smelling, seeing, learning, reasoning, language, and memory
  • Has right and left hemisphere
  • Right hemisphere controls movement and activities on the left side of the body
  • Left hemisphere controls movement and activities on the right side of the body
• Cerebellum


  Part under the cerebrum that controls posture, balance, and coordination
• Stimulus


  Any factor in the environment that may trigger a nerve impulse
• Response


  Reaction to a stimulus
• Sensory organs


  Eyes, ears, nose, tongue, and skin
• Brainstem


  Part that connects the brain to the spinal cord and controls autonomic functions such as coughing, vomiting, breathing, swallowing, digestion, heart rate, and blood pressure
• Effectors


  Muscles or organs
• Reaction time


  Length of time between detection of a stimulus and application of a response
• Spinal Cord


  • Serves as a channel for signals between the brain and the rest of the body
  • Controls simple musculoskeletal reflexes without input from the brain
• Nerve impulse


  Electrochemical signal that move along the nervous system through the neurons
• How the nervous system works

  1. Stimulus received by sensory organ

  2. Information converted into nerve impulse

  3. Nerve impulse travels through spinal nerve, spinal cord, cranial nerve, and brain

  4. Brain processes information and commands a response in the form of nerve impulse

  5. Nerve impulse travels through cranial nerve, spinal cord, spinal nerve, and effector organ

  6. Effector organ does the response commanded by the brain
• Nerve impulse transmission between neurons

  1. Nerve impulse carried by dendrite to cell body

  2. Nerve impulse carried by axon away from cell body

  3. Neurotransmitter produced at end of axon

  4. Neurotransmitter crosses synapse and stimulates dendrite of next neuron
• Divisions of the Peripheral Nervous System

  • Somatic Nervous System
  • Autonomic Nervous System
• Homeostasis


  The body is in a stable state which is attained through feedback mechanism coordinated by the nervous system
• Negative feedback mechanism


  • Reduces changes to help the body to be stable
• Somatic Nervous System


  Associated with the voluntary control of body movements
• Positive feedback mechanism


  • Uses information from sensors to increase the rate of processes in the body
• Parts of the Somatic Nervous System

  • Spinal nerves
  • Cranial nerves
• Spinal nerves


  Carry motor and sensory signals between the spinal cord and the body
• Cranial nerves


  Carry information into and out of the brainstem
• The human body is made of cells
• Autonomic Nervous System


  Associated with the control of involuntary body activities
• In the nucleus of each cell there are chromosomes
• Each chromosome is made of long chain of DNA