Nerves Presentation pt. 2

1. Nerves Presentationpt. 2 Jennie May & Yasmin Ali

2. Central Nervous System • Coordinates the activities between the various parts of the human body. • The central nervous system includes: • Brain • Controls movement, sensation, thinking, memory, speech. (In depth detail of brain will be further on) • Spinal Cord • Transmits messages back and forth between the brain and peripheral nerves.

3. Peripheral Nervous System • Transfers information to and from the CNS. It also regulates movement and internal environment. • The cells that carry to the CNS are called sensory nervous cells, and those carrying from are called motor nervous cells. And these cells send information due to internal organs or external stimuli.

4. PNS Structure • “Left–Right pairs of cranial and spinal nerves with their associated ganglia” • Cranial Nerves • Emerges from or enters the Brain • Sensory, motor or mixed nerves. Humans have 12 pairs. • Spinal Nerves • Originate in spinal cord and extend below the head. • Consists of all mixed nerves. Humans have 31 pairs.

6. Motor Neuron • Motor Neuron Cells carry the information from the CNS to organs, muscles, and glands. • Motor Neuron cells are divided into two subcategories which are Somatic Nervous System and Automatic Nervous System.

7. Somatic Nervous System • It controls : • the skeletal muscles and carries to and from the skeletal muscle due to external stimuli. • sensory organs such as the skin. • The Somatic Nervous system is voluntary with exception to reflex reactions.

8. Autonomic Nervous System • Regulates internally through the smooth and cardiac muscles as well as organs of the digestive ,cardiovascular, etc. • This is an involuntary control unlike Somatic. • This also carries some exceptions such as the diaphragm (breathing), bladder muscles, and heart rate, which can all be controlled. • It is further divided into three subsections: • Sympathetic Division • Parasympathetic Division • Enteric Division

9. Autonomic Nervous System Divisions • Sympathetic Division • Controls activities for increased energy generation. Ex: Flight or Fight. These nerves increase heart rate, dilate pupils, and relax the bladder. • Parasympathetic Division • Serves as the opposite and decreases heart rate, constricting pupils, and contracting the bladder. These nerves are more for activities that control energy expenditures. • Enteric Division • Networks of Neurons in digestive tract, pancreas, and gallbladder. These nerves can be controlled independently, but are usually regulated by the Parasympathetic and Sympathetic Division.

10. http://www.youtube.com/watch?v=dOYOdJG0E0s

11. Receptors • They are used to respond to stimuli. They help process information from the environment. • Focused more on where the action potentials go rather than what triggers them. • Sensory Reception is the detecting of a stimulus by cells which are called sensory receptors.

12. Sensory Receptors • Classification • Exteroreceptors • Outside the body • Heat, light, pressure • Interoreceptors • Inside the body • Blood pressure, body position

13. Sensory Reception • Mechanoreceptors • Touch, pressure, gravity, stretch, movement • Chemoreceptors • Taste and smell • Photoreceptors • Absorb light • Thermoreceptors • Temperature changes • Electroreceptors • Electric stimuli

14. Function of Sensory Receptors • Sensory Transduction • Stimulus energy converted into change in membrane potential. • Receptor Potential: The change in membrane potential • Graded potentials via the magnitude and strength of the stimulus. • Results from the opening and closing of ion channels in the plasma membrane • Amplification • Increasing the stimulus energy in sensory pathways

15. Function continued… • Transmission • Identical action potentials (the magnitude affects the frequency) • Integration • Processing of the sensory information • Adaptation: decrease in responsiveness to repetitive stimuli • Pain and touch receptors