Quest Review

1. Homeostasis

  • The maintenance of a constant environment in the body

  • Important for maintaining i) Temperature ii) Water levels iii) Glucose concentration iv) pH levels

Maintaining Blood pH( Respiratory system and kidneys)

  • Acidosis(Low blood pH): depression of the central nervous system (creates disorientedness and comatose)

  • Alkalosis(High blood pH): hyperexcitability of the nervous system

    • Creates spontaneous nervous stimulation, spasms, muscular contractions and nervousness

  • Kidneys regulate blood at proximal and distal tubules

Maintaining body temperature (Integumentary System)

  • Sweating: body heat stimulates sweat glands to release sweat that later evaporates

  • Vasodilation: capillaries filled with blood draws closer to skin so heat is lost

  • Vasoconstriction: Capillaries get constricted for blood to get taken away from the surface of the skin

  • Piloerection: Hairs “stand up” to trap air that is warmed by body heat

2. Negative Feedback Systems

  • Any homeostatic control system that works with three components

    • Receptor: Detects changes in the internal environment

    • Control center: processes information from the receptor

    • Effector: creates the initial response

  • Small changes are prevented from being to large

3. Nervous System

  • Network of specialized cells that process information and causes reactions

  • Sends, receives, and processes nerve impulses to the body for organs to function

  • Nerves connect the brain to the body to carry information throughout the body in the form of electrochemical signals (or impulses)

  • Reflex arc: a simple nerve circuit that creates an automatic response

Neuron: structual and functional unit of the nervous system

  • Afferent neurons: carries impulses from sensory receptors to the Central Nervous System

  • Efferent neurons: carries impulses from the CNS to the skeletal muscles

  • Interneurons: relays impulses between afferent and efferent neurons

Nerve Signaling: A membrane potential that is a localized electrical gradient

  • Cations (Extracellular)

    • K+ the principal intracellular cation

    • Na+ the principal extracellular cation

  • Anions (Intracellular)

    • Proteins, amino acids, sulfate, and phosphate are principal intracellular aions

    • Cl- principal extracellular anion

Action potential: All or Nothing depolarization

  • 55mV achieves a threshold potential (initial trigger)

Chemical Synapse steps

  1. Action potential depolatizes the plasma membrane at the synaptic terminal

  2. Action potential opens up voltage-gated Ca2+ channels in presynaptic terminal for an influx of Ca2+

  3. Ca2+ concentration causes synaptic vesicles to fuse with the presynaptic membrane

  4. Vesicles release neurostransmitters into presynaptic cleft

  5. Neurotransmitters binds to receptors of ligand-gated ion channels for diffusion of Na+

  6. Neurotransmitters release from receptors to close channels and diffuses out of the synaptic cleft or become degraded by an enzyme

Different Types of Neurotransmitters

  • Acetylcholine: an excitatory neurotransmitter tjay opens up sodium ion channels for depolarization

    • Also inhibitory om cardiac muscle cells to slow down cardiac muscle concentraion, Released by botulism toxin

  • Cholinesterase: released from the postsynaptic membrane to hydrolize Acetylcholine

  • Epinephrine & Norepinephrine: Excitatory and inhibitory that is secreted in the CNS and PNS amd adremal glands

  • Dopamine: Excitatory (sometimes inhibitory) that affects sleep, mood, attention, and learning

    • Lack of Dopamine = Parkinson’s Disease Excessive Dopamine = Schizophrenia

  • Serotonin: Inhibitory, same effects as Dopamine, secreted only in the CNS

Vertebrate Nervous System

Central Nervous System (CNS)

  • Brain and spinal cord

    • Contains fluid-filled spaces (cerebospinal fluid)

  • White Matter: Bundles of myelinated axons

  • Gray Matter: unmyelinated axons, cell bodies and dendrites

Peripheral Nervous System (PNS)

  • Nerves that carry information between organs of the body and the CNS

  • Somatic Nerves: controls skeletal muscles and skin

    • Sensory nerves: relays information about the environment of the CNS

    • Motor Nerves: creates a response to external stimuli

  • Automatic Nerves: controls internal organs, smooth and cardiac muscle

Sympathetic Nervous System: prepares body for stress

  • Dialates pupils

  • Inhibits Salivary glands

  • Accelerates heart

  • Relaxes Bronchi

Parasympathetic Nervous System: restores normal balance

  • Constricts pupil

  • Stimulates salivary glands

  • Slows heart

  • Constricts bronchi

Left Hempishpere: controls the right side of the body

  • Language, math, logic operations, motor control

Right Hempisphere: controls the left side of the body

  • Pattern recognition, spatial relationships, emotions

Brain structures and roles

  • Brainstem (lower brain): functions in homeostasis, coordination of movement, conduction of impulses to and from higher brain centers

  • Medulla & Pons: controls automatic nerve functions, relays information to and from higher brain centers

  • Cerebellum: Coordinates motor activities, relays sensory information, and coordinates motor commands

  • Thalamus: relays sensory information from the cerebrum, regulates emotion and arousal

  • Hypothalamus: Regulates autonomic activity, body temperature, hunger, thirst, and the pituitary gland

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