Physiology exam 2 study guide

• The organization of the Nervous system splits in CNS and PNS. CNS splits to brain and spinal cord. PNS splits to sensory and motor. Sensory splits to visceral sensory (internal organs) and somatic sensory(eyes, skin, ears) . Motor splits to somatic motor (skeletal muscle, voluntary) and autonomic motor (smooth muscle) which then splits to sympathetic and parasympathetic
• The structure of a motor neuron has a big cell body with dendrites that then extend to an axon. A sensory neuron has the cell body in the middle of the axon
• The neurons in the peripheral nervous system include the Schwan's cells and satellite cells. Schwan's cells myelinate and insulate PNS axons. Satellite cells support cell boddies within the gangial of the PNS
• The neurons in the central nervous system include Astrocytes,Microglial, oligondendrocytes, ependymall.

  • Astrocytes helps for the blood brain barrier
  • Microglial cells defend against infections and engulf debris
  • Oligondendrytes myelinate and insulate cns axons
  • Ependymall cells assist in production kf cerebral spinal fluid
• • The receptive segment contains the cell body and dendrites and is controlled by chemical gated channels
  • The initial segment contain the axon hillock and is controlled by sodium and potassium channels in response to receptive segment
  • Conductive segment contains the axon and its branches and is controlled by voltage gated sodium and potassium channels
  • Transmission segment contains synaptic knobs and is controlled by voltage gated calcium pumps and channels
• Resting membrane potential is the electrical potential diffirence across the plasma of the cell which is usually -70mV.
• Excitation postsynaptic potentials increases the likelihood of an action potential occurring to get closer to the threshold (Depolarization)
• Inhibitory synaptic potentials decrease likelihood of action potential (Repolarization)
• The refractory period is the time after an action potential where it is impossible or difficult to fire another action potential
• In the initial segment, opening of sodium channels allows sodium in resulting in a less negative cell or depolarization. Once 30mV is reached, potassium channels open and let potassium ions leaves to make the cell more negative or repolarization. Once the threshold of -55mV then action potential os sent. Hyperpolarization will then take place and keep potassium channels open longer than needed until it reaches -80mV where it will go up and stabalize
• Continous propagation is the constant surge of action potential for unmyelinated axons while Saltitory propagation is for myelinated axons and makes the action potential jump
• The pulse frequency of action potential tells us how intense the sensation is
• Neurotransmitters are chemicals released by the synaptic cleft such as acetylcholine that can either be excitatory (skeletal) or inhibitory (cardiac) where it will attach to a receptor to inhibit or excite channels is broken down at the other end by acetylcholinesterase
• Nicotinic and Muscarinic are the two types of acetylcholine receptors.

  • Nitotinic receptors is a ligand gated channel
  • Muscarinis is a G-protein coupled channel
• For a Muscarinic receptor, acetylcholine will bind to the Gprotein where alpha, beta, and gamma will split off and bind to the channel
• Local anaesthetics work by blocking voltage gated sodium channels
• Curare is a toxin that block or antagonizes Nicotinic receptors so muscles don't contract while Atropine is a muscarinic antagonist
• Catecholamines like norepinephire and epinephrine can't bind to receptors so they really on the second messenger system

  1. Catecholamine binds to a Gprotein which causes it to send the alpha particle to bind with adenylate cyclist to convert ATP to cAMP
  2. cAMP activates kinase which then phosphorylates proteins.
  3. Thus finally leading to ion channels opening up
• Norepinephrine is a neurotransmitter on smooth muscles, cardiac muscles, and glands
• Nigrostrial dopamine system is involved in motor control while mesolimbic dopamine system is involved in emotional award
• Seratonin is associated with mood and behavior
• Gamma aminobutyric acid is the most common neurotrasmitter in the brain. It acts as a inhibitor by opening chloride ion channels causing the cell to hyperpolaroze
• Glysine is an inhibitory
• The blood brain barrier is the complex that surrounds blood vessels in the brain and acts as a barrier between the blood and extracellular space to allow nutrient and filter potential harmful things
• The 4 main regions of the brain is the cerebrum(outer part), Diencephalin(central), Brainstem, cerebellum(inferior Maas in back)
• The precetral gyrus is in the frontal lobe and is in charge of motor control of visceral muscle while the ppostcentral Gyrus located in the parietal lobe is in charge of receiving somatic sensory information
• Brocade area is deep and infront of the central sulcus. It is in charge of motor speech
• Wernickes area is deep and behind the post central gyrus. It is in charge of language comprehension
• The corpus callosum allows both hemispheres of the brain to communicate
• The epithalamus contains the pineal gland, which secretes melatonin
• The thalamus acts as a filter for sensations to reach the cerebral cortex
• The hypothalamus maintains homeostasis and triggers thirst and hunger
• The substantia nigra is important for motor coordination
• The superior colliculi is responsible for visual reflexes
• The inferior colliculi is responsible for auditory reflexes
• The Pons is the respiratory center
• The olive relays proprioceptive information to the cerebellum
• The medulla oblongata is responsible for maintaining vital functions and for coughing, sneezing, and gag reflexes
• The cerebellum coordinates and fine-tunes skeletal muscle movement
• The limbic system is important for emotions, learning, and memory