lec nervous system

what are neurons and their structure

-NERVE CELLS that transfer info within body

-most organells in cell body (soma)

-Dendrites (highly branched extensions of cell body) RECIEVE SIGNALS FROM OTHER NEURONS
-Axon longer extension that TRANSMIT SIGNAL FROM TERMINAL BRANCH TO OTHER CELLS AT Synapses

-Axon joins cell body at axon hillock

what are oligodendrocytes and shwann cells and location?

Oligodendrocyted (IN CNS) and Schwann cells (IN PNS) are glia that form myelin sheaths around axons (provide electrical insulation)

what are the 2 major parts of nervous system? what does each include?

Central Nervous System CNS (BRAIN & SPINAL CORD)

Peripheral Nervous System PNS (network of spinal/cranial nerves linked to brain/spinal cord)

are sensory receptor neurons in cns or pns? are they afferent or efferent neurons and where they carry impulse to?

IN PNS

AFFERENT (arrives)

carry impulse from stimuli to CNS where impulse processed

main function of CNS? what are interneurons? what happens after info processed

integrate/process sensory info

-interneurons create neural circuits, enabling communication between sensory/motor neurons and CNS

-after info processed, motor neurons (efferent) RETURN SIGNALS to PNS , responding with motor output

3 structure types of neurons?

1. Multipolar - multiple short dendrites + long axon (often motor and inter neurons)

2. Bipolar - ONE short dendrite + long/short axon (both structures face opp direction) (interneurons in retina)

3. Pseudounipolar - LONG dendrites + SHORT axon (SENSORY neurons)

what are different ways the delicate tissue of CNS is protected?

-encased in bone or cartilage (ex. skull protect brain)

-surrounded by meninges (protective membrane, covers brain/spinal cord)

-floats in cushioning fluid: cerebrospinal fluid (CSF)

-seperated from rest of body by blood-brain barrier

2 major functions of meninges?

1. Act with CSF to protect CNS

2. Provide supportive framework for cerebral/cranial vasculature

how many meninges (membrane) do fish, amphibians/non-avian reptiles, mammals, birds have and what are thy called

FISH: SINGLE - primitive meninx

AMPH/REPT: TWO - thick outer: dura mater & thin: secondary meninx

MAMMALS/BIRDS: THREE: dura mater, middle: arachnoid mater, inner: pia mater

what is cerebrospinal fluid CSF? where is it found and what 4 functions

CSF: filtered blood plasma in brain/spinal cord/central canal

4 functions:

-SHOCK ABSORBER: CUSHIONS brain/spinal cord

-TRANSPORT nutrients/hormones (to nervous syst tissue)

-REMOVE WASTE (products from cerebral metabolism)

-REGULATE INTRACRANIAL PRESSURE

is CNS connected to or seperated from rest of body. explain

SEPERATED by blood-brain barrier (BBB)(HIGHLY SELECTIVE, semi-permeable formed by tight junctions between endothelial cells lining capillaries, prevent material leak out bloodstream into cns) and structure maintained by astrocytes (glial cells)

BBB is semi permeable and restricts passage of what and allows diffusion of what?

RESTRICT PATHOGENS (virus/bacteria), SOLUTES in blood, LARGE POLAR molec

ALLOW NONPOLAR (O2, CO2, hormones) and SMALL POLAR

ACTIVE TRANSPORT of glucose use proteins

functions of astrocytes

-regulate BBB

-structural support for NEURONS in cns

-DESTROY PATHOGENS (help immunity)

-promote myelin activity of oligodendrocytes

-SUPPLY NEURONS w/ LACTATE (used for energy)

-form GLIAL SCARS to help w/ repair

what 2 sets of neurons does PNS have? why isnt PNS as protected as CNS

-SENSORY (afferent) neurons and MOTOR (efferent) neurons

-PNS not protected by BONE (spine skull) or by BBB (blood-brain barrier)) so more exposed

what are the 2 PARTS of PNS and 2 subparts of one of them?

SOMATIC: voluntary control (has neurons connected w/ skeletal muscles/skin)

AUTONOMIC: involuntary control (affect heart rate, dilation of arteries, digestion, bronchial dilation, salivation, perspiration, pupillary dilation, urination)

-subdivided into SYMPATHETIC and PARASYMPATHETIC

Sympathetic: FIGHT OR FLIGHT

Parasympathetic: REST AND DIGEST (relax/recharge)

what 2 motor neurons do autonomic pathways have? describe them, and describe which subparts of autonomic have short/long of these neurons

-Preganglionic neuron (cell body in CNS, axons in peripheral ganglion)

-Postganglionic efferent neuron in PNS (cell body in peripheral ganglion, axons in effector organ)

SYMPATHETIC: short pre and long post

PARASYMPATHETIC: long pre and short post

what does the preganglionic neuron release? what receptors do postganglionic neurons have that bind to this? (what gated ion channel is this) WHAT CHANGES IN PARASYMPATHETIC? WHAT CHANGES IN SYMPATHETIC?

-PRE release acetylcholine (ACh)

-POST has nicotinic receptors that bind ACh (receptors are LIGAND-gated ion channels)

PARA: POST release ACh, and target effector organ has muscarinic receptors, which are coupled to G protein receptor complexes (slower response than nicotinic receptors

SYMPATHETIC: POST release norepinephrine (NE) which binds to adrenergic receptors on effector organ (binding can be stimulatory or inhibitory depending on receptor: ALPHA-adreneric receptor produce EXCITATORY response, BETA produce INHIBITORT)

whats the only animal without a nervous system.

-Sea Sponges

-Cnidarians (jellyfish/hydra) have decentralized nervous system (neural control distributed throughout body, rather than controlled by central brain)

-lack brain but have a Nerve Net (system of interconnected neurons that coordinates simple behaviours)

what type of nervous system does each group of animal have and what this mean and what special features do they have?

cnidarians (jelly/hydra), echinoderms (sea stars), flatworms, insects, cephalopods (octopi/squid)

CNIDARIANS: Decentralized (neural control throughout body), no brain, have nerve net (system of neurons)

ECHINODERMS (sea stars): Decentralized, no brain, have nerve ring (encircles mouth) and 5 radial nerve cords (each arm)

FLATWORMS: centralized (brain control), CNS made of a small bilobed brain n 2 main nerve cords, and PNS have transverse nerves

INSECT: COMPLEX!!!! both centralized/decentralized, but more decentralized than vertebrates. have brain, ventral nerve cord, and ganglia (act as mini brains by process sensory info + control movement/breathing without brain input. SO BRAIN ISNT VITAL FOR SURVIVAL, A HEADLESS INSECT CAN WALK/BREATHE thru spiracles b/c ganglia manage those functions on its own)

CEPHALOPODS: MOST COMPLEX invertebrate system, both centralized/decentralized. Have CENTRAL BRAIN organized into lobes and decentralized NEURON NETWORK IN ARMS (arms kinda act independently to central brain, a severed arm can still move/respond to stimuli) (central brain handles higher-level functions and arms handle local control of movement)

what is commin in ALL VERTEBRATE NERVOUS SYSTEMS

-more CENTRALIZED

-all have CNS with brain/spinal cord and PNS with peipheral sensory/motor nerves

whats one interesting difference between invertebrate vs vertebrate nervous system

nerve cords of invertebrates located ventrally (along belly

vertebrates located dorsally (along back