Physiology Mid Term Exam PDF

Physiology: ​ Focuses on the functions of the body, often at cellular or molecular levels ​ Integrated physiology focuses on how different organ systems work together to maintain homeostasis ​ Smooth Muscle Cells: long and slender, found in many organs ​ Blood Cells: flattened dis...

Physiology: ​ Focuses on the functions of the body, often at cellular or molecular levels ​ Integrated physiology focuses on how different organ systems work together to maintain homeostasis ​ Smooth Muscle Cells: long and slender, found in many organs ​ Blood Cells: flattened disc or spherical, red, transport oxygen and carbon dioxide, white fight off infection ​ Bone Cells: responsible for the maintenance of the bone, recycle calcium and phosphate ​ Fat Cells: spherical, excess energy obtained is stored as fat, cells get larger and multiply ​ Cells grouped together=tissue ​ 2+ tissue=organ ​ 2+ organ=organ system Neurons and Nerve Tissue: ​ Transmit signals for communication ​ Branches used to receive and transmit messages ​ Neurons process information Muscle Cells and Epithelium: ​ Specialized to contract ​ Skeletal muscle cell: involuntary ​ Smooth muscle cell: involuntary ​ Cardiac muscle cell: involuntary Epithelial Cells and Epithelium: ​ Sheet like layer of cells ​ Lines external body surface, and hollow organs ​ Functions barrier and transport membrane Epithelium Glands: ​ Manufacture a product ​ Exocrine glands (sweet, salivary) ​ Endocrine glands ( pituitary, adrenal) Connective Tissue: ​ Most diverse of four tissues ​ Characterized by extracellular matrix ​ Anchor link structure of body ​ Fills internal spaces ​ Stores energy Organ Systems: ​ Integumentary: skin, keeps foreign particles out ​ Skeletal: support, structure, protects internal organs ​ Muscular: movement, generate heat, excess pool of amino acids  ​ Nervous: provide communication between cells, signal and release neurotransmitters into small gaps ​ Endocrine: provide communication between cells, release hormones into bloodstream ​ Cardiovascular: transports oxygen and nutrients through the body, via the bloodstream ​ Lymphatic: filter liquid lost from cardiovascular system ​ Respiratory: bring in oxygen, remove carbon dioxide ​ Urinary: filter blood, eliminate waste ​ Digestive: breakdown and absorb food into the body ​ Reproductive: generate offspring ( connected to endocrine system) Homeostasis: ​ Maintain relatively stable internal conditions even though outside is changing ​ Disruption is the basis of disease and death ​ Environmental Disturbance: high altitude, hat climate, cold climate, blood glucose drops Generic Homeostatic Control System: ​ Receptor: cells sensitive to a particular variable ​ Integrating: nervous tissue in brain ​ Effector: muscle or glands, carry out responses Negative Feedback Mechanism: ​ Once response has been generated negative feedback acts to shut off the response in order to prevent over durrection of the system Positive Feedback Mechanism: ​ The response of the system enhances the original stimulus Plasma Membrane: ​ Separates intracellular fluids from extracellular fluids ​ Dynamic role in cellular activity (compartmentalization, localization, and organization, transport, signal detection, cell to cell communication) Permeability: ​ Freely Permeable: allow any substance to pass without difficulty ​ Selectively Permeable: permit the passage of some materials and the passage of others ​ Impermeable: nothing is able to pass through it Division of Nervous System: ​ Somatic: voluntary, skeletal muscle ​ Autonomic: involuntary, smooth muscle, cardiac muscle , glands ​ Sensory: afferent ​ Motor: efferent Ions: ​ Charged particles that have either gained or lost electrons ​ Anion: negatively charged particle ​ Cation: positively charged particle Major Cellular Ions and Membrane Potential: ​ Sodium: (Na+) is the major extracellular ion ​ Potassium: (K+) is the major intracellular ion ​ At rest the inside of the cell is negatively charged relative to the outside of the cell Why is Resting Membrane Potential Important: ​ Propagation of electrical signals through the heart ​ Muscle Contraction ​ Secretion of hormones ​ Neurotransmitter release ​ Transmission of nerve impulses Ion Passageway Across Membranes: ​ Leakage: usually ion specific, always open ​ Voltage Gated: open/close in response to changes in voltage across membrane ​ Ligand Gated: open/close in response to chemical messenger attaching to receptor on membrane ​ Mechanically Gated; open/close in response to a mechanical event on the cell Resting Membrane Potential: ​ Under resting conditions cells have a higher intracellular K+ concentration and a high extracellular Na+ concentration ​ Protein ions cannot leave cell ​ Plasma membrane is highly permeable to k+ ​ Na+ leakage compared to k+ leakage are not as permeable but do allow for some movement ​ The cell requires another mechanism by which it can bring potassium in and move sodium out ​ Na-k pump or Na-k ATP phase: is extremely important in maintaining the resting membrane potential by pumping 3 Na+ ions out and 2k+ ions back into the cell ( requires ATP to perform tasks) Describing Changes in Membrane Potential ​ Normal resting potential in 70 mv ​ Depolarization: if the voltage increases relative to the resting membrane potential ​ Hyperpolarization: if the voltage decrease relative to the resting membrane potential ​ Repolarization: restoration of resting membrane potential: What Causes Changes in Membrane Potential: ​ Stimulus: any changes in the environment of the cell ​ May cause ion channels to open and close ​ As a result ions will move in/out of the cell ​ Membrane potential changes: graded/action potential Graded Potentials: ​ Stimuli cause voltage gated ion channels to open ​ Sometimes, we don't get enough Na+ into the cell to get 30 mv ​ If a change in charge occurs, but its not an action potential it's called a graded potential Strength and Size of Graded Potential: ​ Graded potential are small changes in membrane potential ​ A stronger stimulus produces a larger change in the voltage Postsynaptic Potential (PSP): ​ Change in membrane potential of postsynaptic membrane ​ Can be either inhibitory postsynaptic potential or excitatory postsynaptic potential Excitatory Neurotransmitter: ​ Increases likelihood of an AP occurring on postsynaptic neuron ​ Leads to an excitatory postsynaptic potential\ ​ Most abundant is acetylcholine Acetylcholine works via opening NA+ ion channels Inhibitory Neurotransmitter: ​ Decreases likelihood of an AP occurring on postsynaptic neuron ​ Leads to inhibitory postsynaptic potential ​ Most abundant in brain GABA ​ GABA works via the opening of Cl-ion channels Threshold and Development of an Action Potential: ​ Membrane potential must depolarize to SSMV- threshold ​ Once charge reaches SSMV more Na+ gates open, and more Na+ is added to the cell , until 30 mv is reached Action Potential: ​ Specialized channels exist on the cell membrane ​ Voltage-gated Na+ and k+ channels ​ Only open/close when membrane potential changes Action Potential Sequence of Events: ​ 1.) stimulus causes alteration of resting membrane potential ​ 2.) if graded [potential is strong enough to cause the membrane potential to reach threshold then voltage gated Na+ channels open ​ 3.) membrane potential quickly climbs from -70 to +30 ​ 4.) Na+ channels close, and k+ open ​ 5.) Repolarization due to k+ exiting cells ​ 6.) k+ channels close slowly and membrane becomes hyperpolarizes for short duration Linking Ap to a Nerve: ​ They are the cells that are designed to detect stimuli, and then communicate with other cells ​ Stimulus - Receptor - Integrating Center - Effector - Response Details of Neuron: ​ Dendrites: detect stimuli ​ Axon: develops and sends action potentials ​ Cell body: nucleus Myelinated Neurons: ​ Whitish, fatty covering of axons ​ Associated with long, and large diameter nerve fibers ​ Conduct impulses at a much faster rate than unmyelinated fibers Syanpses: ​ Presynaptic neuron: The neuron before the synapse takes place ​ Postsynaptic neuron: The neuron after the synapse takes place Types of Synapses: ​ Electrical Synapses: not as abundant, found in brain and heart, signal travels through gap junctions ​ Chemical synapses : abundant, found through the body, neurotransmitter released from one neuron open/close ligand gated ion channels on neighbouring neurons Events Occuring at a Chemical Synapse: ​ Step 1: normal stimulus for neurotransmitter release is the depolarization of the synaptic knob by action potential ​ Step 2: Cal;cium ions rush into the knob and trigger the release of Ach into the synaptic cleft ​ Step 3: released ACh diffuses across the synaptic cleft and binds to the chemically gated Na+ receptors on the postsynaptic membrane. The more ACh released the more receptors respond and larger depolarization. If depolarization is great enough, an action potential will appear ​ Step 4: ACh molecules that bind to receptor sites are generally broken down within 20 msec of their arrival Ion passageway Across Membranes: ​ 4 types of ion channels can exist on a membrane ​ Leakage: usually ion specific, are always open. ​ Voltage Gated: open/close in response to changes in voltage across membranes ​ Ligand gated: open/close in response to chemical messenger attaching to receptor on membrane ​ Mechanically Gated: open/close in response to a mechanical event on the cell Events Occuring at Synapse: ​ 1) An arriving action potential depolarises the synaptic knob ​ 2) Calcium ions enter the cytoplasm, and after a brief delay, ACh is released through the exocytosis of synaptic vesicles ​ 3)ACh binds to sodium channel receptors on the postsynaptic membrane producing a graded depolarization ​ 4) Depolarization ends as ACh is broken down into acetate and choline by acetylcholinesterase (AChE) ​ 5) The synaptic knob reabsorbs choline from the synaptic cleft and uses it to synthesise new molecules of acetylcholine (ACh) Chemical Synapses and Postsynaptic Potential: ​ Change in membrane potential of postsynaptic membrane ​ Can be either an inhibitory postsynaptic potential or excitatory postsynaptic potential Excitatory Neurotransmitter: ​ Increases likelihood of an AP occurring on postsynaptic neuron leads to an excitatory postsynaptic potential (EPSP) ​ Most abundant is acetylcholine ​ Acetylcholine works via opening NA+ ion channels Inhibitory Neurotransmitter: ​ Decreases likelihood of an AP occurring on postsynaptic neuron leads to an inhibitory postsynaptic potential (IPSP) ​ Most abundant in brain GABA ​ GABA works via the opening of Cl-ions channels Na+ and k+ not the only ions responsible for changing membrane potential Types of Neurotransmitters: ​ Different types: Acetylcholine, norepinephrine, dopamine, serotonin, GABA( gamma aminobutyric acid) Acetylcholine: ​ Both CNS and PNS ​ Binds to muscarinic receptors and also nicotine receptors ​ Can have both excitatory or inhibitory actions depending on the type of receptor it binds to ​ Major neurotransmitter at neuromuscular junction Norepinephrine: ​ Both CNS and PNS ​ Neurotransmitter in the brain can be both excitatory or inhibitory ​ A major neurotransmitter of the sympathetic nervous system low levels can lead to depression Dopamine: ​ Mainly in CNS ​ Excitatory and inhibitory neurotransmitter ​ Amphetamines interfere with reuptake of dopamine via the dopamine transporter and also interfere with filling of vesicles with dopamine ​ Dopamine neurotransmission is increased in schizophrenia Serotonin: ​ CNS ​ Mainly inhibitory role ​ Implicated in sleep regulation, migraines, appetite and mood regulation GABA: ​ Main inhibitory neurotransmitter in CNS ​ Binding of GABA receptor opens up chloride channels ​ Chloride ion rushes into cell and makes inside of cell more negative Nervous System: ​ Collects information about the environment analyses it and initiates the appropriate response ​ Monitor Sensory Input: respond to stimuli occurring inside and outside the body, job performed by sensory neurons ​ Integration: process sensory information and initiate response, job performed by interneurons ​ Motor Output: send messages to muscles/glands to respond to original stimuli, job performed by motor neurons ​ Stimulus - receptor - integrating center - effector - response Central Nervous System Facts: ​ 15% o resting carbon monoxide ​ 2% of body weight ​ 20% of oxygen consumed at rest ​ 50% of glucose consumed at rest ​ Glucose is main energy supply ​ Can use ketone bodies for energy Protection of CNS: ​ Bone: cranium, vertebral column ​ Connective Tissue: 3 layers of meninges (dur,arach, pia mater) cover both brain and spinal chord ​ Fluid: cerebrospinal fluid, bathes the brain and spinal cord, provides nutrients Blood Brain Barrier: ​ Is protective mechanism that helps maintain a stable environment for the brain formed by tight junctions between the endothelial cells of capillaries in brain ​ Many drugs are unable to pass the barrier, therefore bo effect on CNS Cerebral Hemispheres: ​ Form the superior part of the brain and make up 83% of its mass ​ Contain ridges and shallow grooves ​ Contain deep grooves called fissures ​ Separated by longitudinal fissure Major Lobes: ​ Frontal ​ Parietal ​ Temporal ​ Occipital ​ Insula Cerebral Cortex: ​ Accounts fo 40% of brain mass ​ Enables sensation, communication, memory, understanding and voluntary movements ​ Hemisphere acts contralaterally ​ Hemispheres are not equal in function Functional Areas of Cerebral Cortex: ​ Motor areas: control voluntary movement ​ Sensory areas: conscious awareness of sensation ​ Association areas: integrate information Sensory Areas of Note: ​ Primary somatosensory cortex: receives information from skin and skeletal muscle ​ Somatosensory association cortex: receives sensory input ​ Visual/Auditory areas: receives visual information the eye, sound stimulus ​ Olfactory, Gustatory and vestibular Cortices: sense different odors, taste and conscious awareness of balance White and gray matter: ​ White matter is made up primarily of myelinated neurons ​ Gray matter is made up primarily of interneurons and action cell bodies ​ White: 60% of CNS, myelinated exons ​ Gray: 40% of CNS, interneurons synapses Somatic Ns- Sensory Info: ​ Refers to skeletal muscle ​ For the most part under voluntary control ​ Afferent information carried to CNS through dorsal root ​ Efferent information carried to effector organs, muscle via ventral root inforelayed to brain for interpretation Reflex Arc: ​ Autonomic response to a stimulus ​ Always predictable ​ No conscious integration required by brain Autonomic Nervous System: ​ Sympathetic Nervous System: role is to get an organism ready to get away from danger. Places us on high alert ​ Parasympathetic Nervous system: role is to keep energy use low ​ Two systems work in opposition Sympathetic: thoracic and upper lumbar region Parasympathetic: brainstem and sacral region Visceral Functions: ​ ANS controls visceral functions ​ Most functions related to ANS are reflexive ​ Specific receptors: baroreceptors, chemoreceptors, nociceptors