Regulation: Answer Packet MRS. ZUCCARELLI BIOLOGY 9H A true nervous system involves receptors, nerve cells, and effectors. Sensory Input or sensory receptors[p610]: Specialized structures designed to detect stimuli (pain/pressure) 1
List and explain the various types of sensory receptors [p623-624] Pain Receptors = indicates tissue damage; all over body Thermorecpetors= detect heat and cold; skin and internal organs Mechanoreceptors = touch, pressure, stretch, motion; ears Chemoreceptors= sensitive to chemicals; external nose and mouth, internal monitor chemicals in blood Photoreceptors = sensitive to wavelengths of light; eye Nerve cells (neurons) carry messages (impulses) throughout the organism. Contrast sensory neurons, interneurons and motor neurons. [p610] Neurons that carry information about stimuli to the CNS (brain and spinal cord) Neurons that relay the message entirely within the CNS Neurons that carry responses to effectors (muscle or gland) 2
The effectoris a specialized structure that responds to the command of the nervous system. If the effectoris a gland it will increase or decrease its activity. If the effectoris a muscle it will contract. Stimulus [p610]: Environmental change (physical or chemical), detected by the PNS (nervous tissue outside of the brain and spinal cord) Create an abstract model of the nervous system pathway responding to stimuli, include all of the bolded terms above in your model (p610; figure 28-1): 3
A Reflex Arc [p611] According to the reading (figure 28-2), explain and illustrate a reflex arc below. Reflex Arc 3 kinds of neurons respond to a stimulus Automatic response to stimuli is known as a reflex Nervous system pathway regulating reflexes is the reflex arc 1. Sensory neurons carry impulses from receptors to the brain and spinal cord 2. Interneurons(associative) relay impulses to the motor neurons (blocking antagonistic muscles, encouraging appropriate muscles) 3. Motor neurons carry impulses from the spinal cord to the muscle 4
IMPULSE TRANSMISSION: DENDRITE SYNAPTIC KNOBS CELL BODY NUCLEUS DENDRITES AXON NODES OF RANVIER TERMINAL BRANCHES SCHWANN CELL NUCLEUS SCHWANN CELL MYELIN SYNAPTIC KNOB 5
Dendrites: receive signals, starting point of impulse (electrical signal) Axon: carries impulse away from cell body toward synaptic knobs, insulated with myelin, impulse conduction only at Nodes of Ranvier Synaptic Knobs: contains neurotransmitters, send impulse from one neuron to the next, last stop on the neuron The nerve impulse [p613] is an electrical signal that travels along the nerve, beginning at the dendrite and ending at the synapse. A resting potentialis maintained across the membrane of the neuron until it is depolarized, resulting in an action potentialif the voltage thresholdis crossed. Ion pumps maintain the -70mV resting potential. What ions are normally maintained inside and outside of the membrane of a neuron? How is the resting potential maintained? 6
Action Potential Na + outside (+ charge), K + inside (- charge) Unbalanced diffusion of K + (diffusing out, pumped in) and Na + (slowly diffusing in, less channels) Active transport pumps, 3 Na out 2 K in 7
Depolarizationis a change in the charge of a neuron. This occurs when stimuli change the cell s permeability to Na + ions. More Na + ions rush into the cell causing the membrane charge to change from -70mV to -50mV. At this point the threshold level for an impulse is met. Explain what is meant by action potential and impulse conduction (transmission) below [p614-615]. Once the threshold level is met Na + gates open allowing a rush of Na+ to enter the cell, causing a greater positive charge The first action potential occurs at the site of stimulation An action potential causes a depolarization of the next adjacent location on the neuron (domino effect) Na + and K + levels are returned utilizing ion channels and pumps described earlier Following the passage of an impulse, there is a brief period during which the nerve cell membrane cannot be stimulated to carry impulses, the refractory period 8
Impulse speed and stimulus strength are both extremely important factors in sending information throughout the nervous system. Impulse speed is expedited due to the presence of what insulating factor? How does it allow for faster transmission? [p615] Myelin sheath surrounds axon, leaving exposed areas called nodes Action potentials jump from node to node 30x faster with myelin (150 meters per second vs5 meters per second) 9
An action potentialis an all-or-none response, meaning all depolarization events MUST occur by causing the SAME change in voltage across the membrane. However, the body is able to differentiate between strong stimuli and weak stimuli. Explain this phenomenon below. [p615] The frequency and number of action potentials increase with a strong stimulus Transmission at the synapse(junction between the synaptic knob of one neuron and the dendrite of the next). Label the structures involved in the synapse diagram and describe how an impulse has the ability to travel from one neuron to the next. List several examples of neurotransmitters (names are sufficient). [p616] 10
Synapse Synapse = space between knob of one neuron and dendrite of the next Electric Synapse = action potential at knob directly causes a depolarization at dendrite Chemical Synapse = neurotransmitter (chemical) released from knob, diffuses across space, binds with receptor on dendrite which triggers an action potential; neurotransmitter broken down by ENZYMES once signal is sent to prevent continuous stimulation Examples of Neurotransmitters = acetylcholine, epinephrine, norepinephrine, serotonin, dopamine NEUROTRANSMITTER SYNAPTIC KNOB SYNAPSE DENDRITE (WITH RECEPTORS) 11
Nervous regulation in humans consists of the central nervous system(cns) and the peripheral nervous system(pns). Create the graphic organizer outlining the divisions of the human nervous system. Include both the CNS and the PNS and give a brief description of the terms utilized [p615 figure 28-9]. PNS CNS Sensory Motor Brain Spinal Cord External Internal Autonomic NS Somatic NS Sympathetic Parasympethetic The CNSis made up of the brainand spinal cord. The spinal cordgoes from the base of the brain down through the vertebraeof the spinal column and connects the nerves of the peripheral nervous system with the brain. The spinal cord is protected by the vertebrae, three tough membranes called the meninges, and cerebral spinal fluid (CSF) The brainis a cluster of nervous tissue protected by the cranium(skull), meninges, and CSF. The major parts of the brainare the cerebrum, cerebellum, and brainstem, thalamus, and hypothalamus. Label (and color if you would like) the parts of the brain in the diagram. Briefly describe the function of the structures listed [620-622]. 12
Cerebrum = largest, complex; divided into hemispheres; connected with corpus callosum; outer region is cerebral cortex including temporal lobe, occipital lobe, frontal lobe, and parietal lobe Cerebellum = coordination and control of balance and fine motor skills Brainstem (medulla, pons) = filters info going to the brain, regulates sleep, breathing, coordination Thalamus = regulation of sensory info to the brain Hypothalamus = temperature, blood pressure, hunger, thirst, emotion THALAMUS FOREBRAIN CEREBRUM HYPOTHALAMUS Human Nervous System: CNS CORPUS CALLOSUM MIDBRAIN HINDBRAIN CEREBELLUM PONS MEDULLA OBLONGATA SPINAL CORD 13
1. D 2. C 3. D 4. B 8. Sensory neurons carry information to the CNS. Interneuronsreceive info from Sensory neurons and integrate a response. Motor neurons carry commands from the CNS to muscles and other cells 9. Sensory receptors detect tap. Sensory neurons relay signals to the spinal cord. Motor neuros signal quadriceps to contract. Interneurons block motor neurons from signaling flexor muscle. The leg jerks. 10. Na channels close and K channels open. K diffuses out, restoring the negative charge. The Na / K pump redistributes the ions, restoring the resting potential. 11. The threshold is the minimum intensity of stimulus needed to Initiate an action potential. An action potential is the same strength regardless of the stimulus intensity. 12. Sympathetic division increases heart rate, dilates pupils, relaxes airways. Parasympathetic decreases heart rate,constricts pupils, constricts airways. 16. Drugs may cause neurons to release excess neurotransmitters, stop snzymes from breaking down neurotransmitters, or mimic neurotransmitters. 17. Figure 28-6! 18. a. dendrites (a) receive signals from other neurons. Signals travel away from a cell body along an axon (b) toward another cell. 18. cont.. b. Myelin sheath. Without a myelin sheath, a signal travels too slowly. c. Axon knob. Vesicles release neurotransmitters into the synaptic cleft. They diffuse across the gap to the receiving neuron s receptors. 14
Endocrine System [ch 32] The endocrine system plays a very important role in maintaining homeostasis. Explain where hormones are produced, how they travel, and why they are only capable of eliciting a response in target cells. [p699-700] Hormones = chemical messengers Released from ductless glands (endocrine glands) and travel in bodily fluids (the blood stream) Target cells have receptors that bond specifically with hormones and stimulate a specific response from the target cell Longer response time (minutes to days) Endocrine System [ch 32] 15
Endocrine System [ch 32] Endocrine glands do not secrete their hormones at a constant rate. The rate varies with the needs of the body. In most cases, chemical stimuli, including other hormones, regulate the secretions of the endocrine system. In a feedback mechanism, the last step in the process sends back information to affect the first step. Positive feedback reinforces the first step. Negative feedback opposes the first step. 16
Endocrine System [ch 32] There are two mechanisms for endocrine action. The one messenger model and the two messenger model. Compare and contrast the two mechanisms below. [p710] *Steroid *Lipid soluable *Cross membrane and elicit cell response One Messenger Model Both *Create a cellular response *Require Receptors *Nonsteroid *modified amino acids, small polypeptides *bind to receptor protein, secondary messenger activate the cells response Two Messenger Model 17
Endocrine System [ch 32] Several structures within the body are responsible for endocrine responses, including: hypothalamus, pituitary, thyroid, pancreas, and adrenal glands. Indicate hormones produced by the above structures and briefly outline their role. [p710-715] Endocrine System [ch 32] Hypothalamus: regulates temp, hunger, thirst, controls the pituitary with RELEASING FACTORS (hormones) Pituitary: master gland, posterior = ADH and oxytocin; anterior = FSH, LH, ACTH, TSH, GH Thyroid: neck; thyroxinemaintains metabolism, calcitoninregulates uptake of Ca+ into cells Pancreas: abdomen; Insulin (alpha cells) and glucagon (beta cells) Adrenal glands: adrenalin (other corticosteroids); fight or flight response (emergencies) 18
pineal hypothalamus pituitary thyroid parathyroid thymus adrenal gland pancreas ovaries testes Hypothalamus & Pituitary Gland (P) 19
Hypothalamus & Pituitary Gland (A) 20
Endocrine System [ch 32] Regulation of Plant Growth [p477-482] Chemical messengers, called hormones, regulate plant growth. Hormones are produced by actively dividing tissues at the tips of roots and stems. Auxins stimulate plant growth by stimulating cells to lengthen. Cytokinins stimulate plant growth by increasing cell division. The growth of a plant in a specific direction in response to a stimulus is called a tropism. Positive tropism growth toward the stimulus Negative tropism growth away from the stimulus Phototropism stimulus (physical or chemical change in the environment) of light Therefore, positive phototropism stems bend toward the light. Growth responses of tropisms are caused by uneven distributions of auxins. Geotropism stimulus of gravity Thigmotropism stimulus of touch 21
Endocrine System [ch 32] 6. a 8. a 13. Allows steroid hormones to pass through the plasma membrane and enter the target cell 14. Hypothalamus signals the anterior pituitary with releasing hormones to secrete hormones. The posterior pituitary stores hormones made int eh hypothalamus and secretes them after receiving nerve signals from the hypothalamus. 15. TSH stimulates the thyroid to secrete thyroxin 16. If Ca levels are too high, thryroid secretes calcitonin, which causes calcium to move from the blood to the bones. If levels are too low, parathyroid secretes parathyroid hormone, releasing calcium from the bones into the blood 17. Diabetes is a disease in which body cells are unable to absorb glucose from the blood. 18. Epinephrine prepares the body for urgent action by increasing heart and breathing rate Endocrine System [ch 32] 21. a. persons with diabetes: glucose level spikes two hours after eating, then drops sharply. Person without diabetes: glucose level remains steady b. diabetes causes uneven glucose levels because either there is not enough insulin, or the cells do not respond to it by taking up the glucose 22
Nervous System Disorders Cerebral Palsy Description: A form of paralysis denoted by jerky, spastic, writhing movements resulting from damage to the portion of the brain that controls muscles. Cerebral Palsy is a group of syndromes with a common result. Treatment: Medical Attention, Physical Therapy Nervous System Disorders Meningitis Description: Inflammation of the meninges, the membranes that surround the brain and spinal cord (viral or bacterial) Treatment: Vaccination (prevention), Medical Attention 23
Nervous System Disorders Stroke Description: A disorder resulting from a hemorrhage in the brain or a blood clot in a cerebral blood vessel which may cause brain damage. Treatment: Proper diet and exercise (prevention), Medical Attention, Physical Therapy Nervous System Disorders Polio Description: A viral disease that affects the central nervous system and often results in muscle damage to the legs and/or arms. Treatment: Vaccination (prevention), Medical Attention 24
Nervous System Disorders Multiple Sclerosis Description: Autoimmune disease that affects the central nervous system. Myelin is lost in multiple areas, leaving scar tissue called sclerosis. These damaged areas are also known as plaques or lesions. Sometimes the nerve fiber itself is damaged or broken. Treatment: Medical Attention Endocrine System Disorders Hyposecretion Too little hormone is produced by a gland (hormone deficiency) Hypersecretion Too much hormone is produced by a gland (excess hormone) 25
Disorders Diabetes Mellitus Inability to regulate blood sugar due to a lack of insulin Type 1 Diabetes (juvenile-onset diabetes): the body's immune system destroys the cells that make insulin; children and young adults; 5 to 10% of all diagnosed cases Type 2 Diabetes (adult-onset diabetes): the body fails to use insulin properly because cells are resistant; 90 to 95% of all diagnosed cases of diabetes Treatment: monitoring blood sugar levels, proper diet (little to no sugar), exercising, medical attention 26