Nervous And Endocrine System Flashcards
What is the Central Nervous System (CNS)?
-Consists of the brain and spinal cord.
-Integrates and processes info.
What is the Peripheral Nervous System (PNS)?
-Links CNS with the body.
Describe the Nervous System
-Contains the brain, spinal cord, and nerves which connects to the rest of the body.
What is Homeostasis?
-A state of relative stability in the body (HR, temp, ph, blood pressure, sugar, oxygen, sodium).
Describe Somatic
-Part of the PNS
-controls the skeletal muscles, bone and skin.
-Under conscious control. (voluntary)
-Sensory - somatic: carries info from the body to the CNS.
-Motor -somatic: carries info from the CNS to the body.
Describe Autonomic
-Part of the PNS.
-Controls certain body organs. (smooth muscle)
-Involuntary.
-Regulates and maintains homeostasis. (Consistency of the environment)
-Sympathetic and parasympathetic systems work in opposition to control the organs.
Describe sympathetic
-Part of PNS.
-Activated in stressful situations.
-“Fight”, flight, freeze.”
-Physiological changes include
Increased: heart rate, blood pressure, breathing, airways, release, epinephrine, pupils.
Decreased: digestion, urine production.
Describe Parasympathetic
-Acts to restore and conserve energy.
-“Rest and digest.”
Increased: digestion, urine production.
Decreased: heart rate, breathing, pupils, airways.
What are the 2 basic cell types in the nervous system?
-Neuron: function cell of the nervous system.
-Glial cells: support cells for the nervous system.
What is a neuron?
-1 of the 2 basic cells types
-Functional cell of the nervous system.
-Have an excitable cell membrane which can conduct an electrical impulse (electrochemical).
-A group of neurons is called a nerve.
-Neurons are always using ATP (Car engine is always idoling to send a message if needed.)
What is a Glial cell?
-1 of the 2 basic cell types.
-Support cells for the nervous system.
-nourishes neurons, removes wastes, defends against infection, supporting frame work.
What are the 3 main types of neurons?
-Sensory neuron (Input) (PNS)
-Interneurons (CNS—>Spinal cord)
-Motor Neuron (Output) (PNS)
What is the Sensory neuron?
-1 of the 3 main types of neurons.
-Input
-Gathers info from the sensory receptors and transmits impulses to the CNS.
What are interneurons?
-1 of the 3 main types of neurons.
-CNS—>Spinal cord
-Acts as a bridge between sensory and motor neurons. Processes sensory information and relay outgoing motor info.
What are motor neurons?
-1 of the 3 main types of neurons.
-Output
-Transmit info from the CNS to the effectors. (Muscles, glands, and other organs.) Effector is triggered by motor neuron.
Describe a reflex arc
-Illustrates a simple neural pathway.
-Enable your body to react quickly in times of danger.
-Simple connections of neurons that explain reflexively behaviours.
-Moves directly to and from the brain or spinal cord before the sensory info is processed.
What is a nucleus?
-Control centre for the cell.
What is the dendrites?
-Projections of the cell body/cytoplasm.
-Carry impulses towards the cell bod.
What is an axon?
-Long projection of the cell body.
-Carry impulses away from the dendrites/cell body and toward other neurons or effectors (muscles and glands.)
What is a synaptic knob (axon terminal)?
-End of the neuron where the cell synapses with another neuron or effector.
Describe the myelin sheath
-Insulation for the neuron.
-Formed by the Schwann cells.
-White coat of fatty protein.
-Prevents the loss of charged ions from the nerve cell (axion).
-helps increase the speed of nerve impulses bc nerve impulses jump from node to node.
Describe the node of Ranvier.
-Gaps between the myelin.
-Exposed pieces of axon.
Describe the neurilemma.
-Membrane around nerve fibers within the PNS.
-Promotes the regeneration of damaged axons.
What is white and grey matter?
-White matter contains myelin and neurilemma.
-Grey matter does not contain myelin and neurilemma.
-In the spinal cord white matter is on the outside and grey matter on the inside.
-In the brain grey matter is on the outside and white matter on the inside.
-Grey matter takes up space.
What is a nerve impulse?
-An electrochemical message created by the movement of ions (Na+\K+) through the nerve cell membrane.
-This is how a message is passed through a neuron.
What is action potential?
-Reversal of charge across the membrane.
Describe the resting membrane potential
-Net negative charge of -70mv (inside of the cell is negative relative to the outside).
-Inactive or resting neuron. (Lot of work to maintain, this way it’s ready to send a signal).
-The charge difference across the membrane (membrane potential) is caused by an unequal concentration of positive ions outside of the cell.
-Na+/K+ pump: Na+ x 3 are pumped out while K+ x 2 are pumped in.
-The inside of the cell is therefore negative compared to the outside.
-The resting membrane is polarized.
Describe depolarization
-The reversal of charge where the inside of the membrane is more positive relative to the outside (+40mV).
-Caused by a stimulus.
-Once stimulated, the Na+ channels open to allow diffusion of Na+ into the cell. The inside then becomes more positive relative to the outside.
-Depolarization in one area triggers neighboring Na+ channels to open=wave of depolarization.
Describe repolarization
-Refers to the restoring of the original polarity.
-Na+ channels close and the K+ open (then quickly close).
-Na+\K+ pump is operational.
-Causes the membrane to overshoot to approximately -90mV (hyperpolarization).
-Quickly brought back to normal resting potential.
-Doesn’t want sodium to go wherever it wants.
-Wants high sodium on outside, high potassium inside to send another message. This is reason for third pump.
-All channels are passive (diffuse naturally). Pump is only thing that uses ATP.
What is the refractory period?
-The time required before a neuron can produce another action potential.
What is the threshold level?
-The minimum level of a stimulus required to produce a response. (~55mV)
-The more intense the stimulus the greater the frequency of the impulses.
What is the all or nothing response?
-A neuron will either fire maximally or not at all.
-A neuron does not fire with differing strength.
Describe a synapse
-The connection (space) between 2 neurons or a neuron and a effector.
-Impulse travels along the axon to the synaptic terminal (end)
-Neurotransmitters enable a pulse to be passed from the presynaptic neuron to the postsynaptic neuron by diffusion.
What are neurotransmitters?
-Chemical messenger secreted by neurons to carry a signal to another neuron or an effector.
What are excitatory neurotransmitters?
-The neurotransmitters cause the ion channels to open in the postsynaptic neuron.
-Sodium flows in and the neuron becomes depolarized.
What are inhibitory neurotransmitters?
-Triggers potassium channels to open and potassium to flow out.
-Neuron becomes hyper polarized.
What is norepinephrine?
-Used by the brain and some autonomic neurons.
What are sensory receptors?
-Nerve endings and cells that detect sensory information.
What is sensory adaptation?
-When the brain filters out repeating or unimportant info.
What are the types of sensory receptors?
- Photoreceptors: stimulated by light energy.
- Chemoreceptors: stimulated by certain chemicals.
- Mechanoreceptors: respond to some form of pressure. (e.g proprioreceptors: body position)
- Thermoreceptors: In the skin, detect heat/cold.
What is serotonin?
-Inhibitory neurotransmitter.
-Regulates temp and sensory perception.
-Involved in mood control.
What is acetylcholine?
-An excitatory transmitter.
-Causes depolarization and contraction of muscle fibre.
What is cholinesterase?
-An enzyme released into the synapse to break down acetylcholine.
-Allows the ion channels to close and the membrane to repolarize.
