Lecture Note 23: Nervous and Endocrine Systems PDF

11/5/20 Chapter 23 Nervous and Endocrine Systems The Nervous System • An organ system that coordinates the actions and transmit signals between body parts • Made of specialized cells called neurons - Sensory neurons - Motor neurons - Inter-neurons Figure 21.9 Dendrites collect electrical signal...

11/5/20 Chapter 23 Nervous and Endocrine Systems The Nervous System • An organ system that coordinates the actions and transmit signals between body parts • Made of specialized cells called neurons - Sensory neurons - Motor neurons - Inter-neurons Figure 21.9 Dendrites collect electrical signals Cell body contains a nucleus and organelles Axon delivers electrical signals to dendrites of another cell or to an effecter cell Terminal boutons 1 11/5/20 Interneurons (within brain or spinal cord) Motor neurons (carry messages from brain to body) Sensory neurons (carry messages from body to brain) See and smell cookies Smile and salivate Figure 21.2 Synapse and Neurotransmitter • Synapse: the junction between each branch end of an axon with the dendrite/cell body of another neuron 2 11/5/20 • Neurotransmitter: chemical messenger that passes information from the transmitting neuron to the receiving cell Dopamine, Cocaine, and Parkinson’s Disease Parkinson’s patients have decreased dopamine levels in the synaptic space Cocaine increases dopamine levels in the synaptic space 3 11/5/20 The Nervous System • Two parts: - Central nervous system (CNS): - brain - spinal cord - Peripheral nervous system (PNS): - nerves to the rest of body Central Nervous System • Brain: rest in the skull; bathed and cushioned by cerebrospinal fluid (CSF) Cerebrum controls language, memory, sensations, decision making Cerebrospinal fluid Skull Cerebellum is responsible for balance, muscle movement, coordination Figure 21.6a Thalamus relay center for sensory information and motor response to the cerebrum Hypothalamus control center for sex drive, pleasure, pain, hunger, thirst, blood pressure, body temperature Brain stem governs reflexes, heartbeat, breathing, swallowing, other automatic functions 4 11/5/20 • Spinal cord: transmit messages to and from the brain; serve as a reflex center Interneurons to and from brain (within spinal cord) Spinal cord Sensory neuron Motor neuron Spinal nerves Vertebrae Cartilage (vertebral disc) Peripheral Nervous System • Somatic Nervous System: voluntary control of body movements via skeletal muscles consciously • Autonomous Nervous System: involuntary control of internal organs below the level of consciousness - Parasympathetic Nervous System: “rest-and-digest” mode - Sympathetic Nervous System: “fight-or-flight” response 5 11/5/20 Somatic Nervous System is involved in: - Voluntary movements (e.g. walking, speaking) - Reflexive movements Interneuron relays signal Sensory neuron senses heat Motor neuron withdraws hand from heat Hot stimulus - Sensations Figure 21.4 First group of senses: general senses - Sensory receptors scattered through the body - Examples: pain, touch, pressure, and body position 6 11/5/20 Second group of senses: special senses - Sensory receptors in complex sense organs in the head - Examples: smell, taste, hearing, and vision Lecture Activity: Color vision and negative afterimage experiment We have photoreceptors in the eyes for red, blue, and green. 7 11/5/20 8 11/5/20 Parasympathetic Nervous System: activities that occur when the body is at rest Examples: - Digestion - Salivation - Urination - Tearing - Defecation - Sexual arousal Sympathetic Nervous System: adaptation syndrome that occurs when there is a threat 9 11/5/20 Discussion: The Organization of the Nervous System The Endocrine System • A system of glands that secrete hormones into the bloodstream to regulate the body - Endocrine glands: organs in the body that synthesize and release their products - Hormones: chemicals that travel to target cells through the bloodstream and generate a response 10 11/5/20 Endocrine glands in the human head and neck and their hormones Pituitary gland: sit at the bottom of the hypothalamus; secrete growth hormones (GH) – stimulate growth, cell reproduction and regeneration 11 11/5/20 Endocrine glands in the human abdomen and their hormones Adrenal gland: sit atop the kidneys; responsible for releasing hormones in response to stress (release Adrenaline) Triangular-shaped Semilunar-shaped 12 11/5/20 Stress hormones secreted from the adrenal glands cortisol (syn. hydrocortisone) Adrenaline (syn. epinephrine) Endocrine glands in the human reproductive organs and their hormones 13 11/5/20 Effects of Nervous and Endocrine Systems • The endocrine system's effects: - Slow to initiate Prolonged • The nervous system’s effects: - Quick to initiate Short lived - Appetite Control: controlled in the hypothalamus - Ghrelin released by the stomach – appetite-stimulating - Insulin released by the pancreas – appetite-inhibiting 14 11/5/20 Stress Response: both nervous and hormonal Sympathetic nervous system is activated – Adrenaline is released by the adrenal gland 15