10c; control systems
- 1. Lecture 10c: Control Systems
- 2. Nervous System Signal moves from brain along nerve to target muscle, which contracts in response Central nervous system (CNS)- brain and spinal cord Peripheral nervous system(PNS)- nerves outside of CNS They are connected to each other and work together
- 4. Neurons Myelin sheaths- cover axons, they increase the speed at which nerve impulses travel 3 types of neurons Sensory: take nerve impulses from sensory organs to the CNS, may be a simple nerve ending or part of an organ like the eye Interneurons: only in the CNS, carry impulses around the CNS only, what thinks Motor: take nerve impulses from the CNS to muscles or glands
- 5. Nerve Impulse Nerve impulses are electrical in nature Nerve impulses are dependent on concentration gradients A neuron maintains: High conc. of K+ inside the cell and a high conc. of Na+ outside the cell, via membrane pumps Inside of cell is negative compared to outside
- 6. Nerve Impulse The difference in charge is called an action potential- the Na+ ions want to go inside the cell, the K+ ions want to go out When the neuron is signaled, gated channels open that allow the Na+ to rush into the cell, making it positive inside Then the Na+ channels close and K+ channels open, and the original gradient is restored This movement of the charged area is the movement of the nerve impulse
- 7. Nerve Impulse The action potentials are self-propagating along the length of an axon- as each area changes its charge it stimulates the next area to do the same Unmyelinated nerves conduct at about 1m/ sec, myelinated nerves conduct at about 1oom/ sec The myelin causes the action potential to jump along the length of the nerve Refractory period- a short time in which the gates can not open- prevents nerve impulse from going backwards
- 9. Synapse How does a signal get from one nerve to the next? The gap between two nerves, or a nerve and a muscle, is called the synapse Neurotransmitters- chemicals which carry the impulse from the first cell to the next across the synapse When the impulse gets to the end of the axon, synaptic vesicles release neurotransmitters into the synapse, and they are received by the next cell
- 10. Synapse There are at least 25 known neurotransmitters, can either excite or inhibit the receptor cell Acetylcholine and norepinephrine are two best known After release, they are very rapidly either resorbed or broken down, so as to not constantly stimulate the cell Each neuron has many dendrites and synapses with many other cells (1000- 10,000) If it gets more excited than inhibited, it will send an impulse
- 11. Drugs Cocaine: prevents resorption of dopamine, which then stays in synapse and continues to stimulate receptor- causes the rush Prolonged use- cells become resistant to dopamine Heroin: binds to endorphin receptors, results in no pain and good feelings Prolonged use- body stops making its own endorphins Marijuana: binds to a receptor for anandamide, which creates a peaceful and contented feeling Prolonged use- psychotic symptoms, hallucinations, etc.
- 12. CNS Brain- very complex organ, we are learning more about it all the time We will discuss: Cerebrum Diencephalon Cerebellum Brain Stem
- 13. Cerebrum!! Communicates with and coordinates the different parts of the brain Mostly white matter- made up of long axons going between brain areas Has 4 lobes: frontal, parietal, occipital, temporal Cerebral cortex is outer layer of grey matter, where higher level thought, voluntary motion, and interpretation of sensation occur
- 15. Cerebrum Each area (lobe) has specific functions Parietal lobe has primary sensory area, receives info from skin, muscles, joints Frontal lobe has primary motor area, makes decisions about voluntary movement and initiates this mvmt. Frontal lobe as prefrontal area, which integrates information received from other areas and is where critical thinking and decision making occurs
- 16. Diencephalon Located under the cerebrum Contains the thalamus receives all sensory info except smell integrates this info and sends it to the cerebrum also involved with memory and emotions And the hypothalamus helps maintain homeostasis regulates hunger, thirst, sleep, body temp link between nervous and endocrine systems
- 17. Cerebellum Located in the back of the head Also receives sensory input Uses info from joints and skeletal muscles to know where body is Uses info from cerebral cortex to know what body parts should be doing Sends motor info to the body Maintains balance and posture Assists in learning new mechanical skills
- 18. Brain Stem Connects the brain to the spinal cord Contains midbrain Visual and auditory reflex centers/ startle Medulla oblongata reflex centers regulate heartbeat, breathing, blood pressure Reflex centers for vomiting, sneezing, swallowing, hiccuping Internal organ control as well Pons- links medulla with midbrain, vital for breathing
- 19. How does the brain combine different stimuli? Limbic system- blends higher mental functions with more primitive emotions Includes the diencephalon parts of the cerebrum Binds memory to reasoning Binds memory, emotion, and reasoning Why we don’t always act on strong emotions
- 20. Memory Short term memory stored in the prefrontal area, but long term memory is different Mixture of semantic and episodic memory Semantic- the words or numbers Episodic- association with people, places, etc. In order to learn, both types must be activated
- 21. Peripheral Nervous System Outside of the CNS- contains nerves, which are bundles of axons Cell bodies are either within the CNS (spinal cord, mostly) or are stored in ganglia- collections of cell bodies within the PNS Sensory neurons have their cell bodies in what is called the dorsal root ganglion- a ganglia that is next to the spinal cord
- 22. Somatic System The part of the PNS that takes sensory info from receptors/ sense organs to the CNS, and takes motor commands from the CNS to the skeletal muscles In a reflex, the command to move comes from the spinal cord, not the brain However, the brain is told about the stimulus that caused the reflex as well
- 23. Autonomic System Automatically and involuntarily controls cardiac and smooth muscle, and gland activity Parasympathetic- promotes the relaxed or normal state Sympathetic- promotes ‘fight or flight’, used in emergency situations
- 24. Endocrine Systems Now, we will talk about the other control system in the body This system consists of glands and tissues that secrete hormones Hormones are secreted directly into the blood, where they have effects on many different bodily functions
- 25. Hormones Hormones bind to receptors on cells that can respond to them, and then the cell undergoes a metabolic change Steroid hormones cause the cell to make a protein Peptide hormones bind to membrane receptor, then start a cascade of events inside the cell- just one binding can have a huge impact
- 26. Hypothalamus and Pituitary Gland Hypothalamus- helps regulate the internal environment Communicates with medulla oblongata Controls secretions of pituitary gland, which is connected to the brain
- 27. Anterior Pituitary Hypothalamus causes the AP to release hormones that stimulate other glands Involved in stimulating gonads to produce gametes and sex hormones, and in production of milk Involved in growth via growth hormone Involved in carbohydrate and fat metabolism More, too, involving thyroid, etc.
- 28. Posterior Pituitary Antidiuretic hormone- released when bld is too concentrated, causes water to be reabsorbed in the kidney Oxytocin- causes uterine contractions and also milk release during nursing
- 29. Thyroid and Parathyroid Glands Thyroid- gland in the neck, hormones it produces increase the metabolic rate Stimulate all cells to work at a faster rate Thyroid and the parathyroid also involve in Ca+ regulation in the body Ca+ important to muscle and nerve function, blood clotting
- 30. Adrenal Glands Sit on top of the kidneys Have inner and outer portion Adrenal cortex (outer) and adrenal medulla (inner) Stimulated by the hypothalamus to produce its hormones
- 31. Adrenal Medulla Produce epinephrine and norepinephrine Helps the sympathetic nervous system in response to an emergency Short-acting
- 32. Adrenal Cortex Produce mineralocorticoids Ex. aldosterone, regulates salt and water volume and glucocorticoids Ex. cortisol, regulates carb, protein, and fat metabolism
- 33. Pancreas Two types of tissue, exocrine discussed in digestion Other type is endocrine, discusses here Produces insulin and glucagon Glucagon- secreted between meals, when bld glucose is low- stimulates liver to break down glycogen to glucose- it raises bld glucose levels
- 34. Pancreas Insulin secreted when blood glucose is high, stimulates uptake of glucose by cells-- so insulin lowers bld glucose level Diabetes Mellitus- Body cells do not take up or metabolize glucose- cells need glucose even though there is plenty in the blood Type I- the pancreas does not produce insulin- must take insulin injections Type II- liver and other cells become resistant to insulin due to poor health and eating habits End results of both types can be the same: blindness, kidney disease, circulatory disorders, death