Biology 12 Brainiac: ______________________Nervous System

Chapter 28Can an Injured Spinal Cord Be Fixed?

Injuries to the spinal cord disrupt communication between the central nervous system (brain and spinal cord) and the rest of the body- There are millions of nerve fibres make up the spinal cord, it is well protected by vertebrae from being severed but they can be crushed resulting in scar tissue that impedes the signals from passing- There are different locations where these injuries can occur from resulting in debilitating injury

Christopher ReeveThe late actor Christopher Reeve

- Suffered a spinal cord injury during an equestrian competition- Two vertebrae were in his neck were fractured, crushing the spinal cord at the base of his skull and

causing quadriplegia- Was an influential advocate for spinal cord research

Unit M & N StandardsCoreI can create a graphic organizer for the divisions of the nervous system.I can relate parts of the brain to various body functions. I can describe how the nervous and endocrine systems work together and provide a relevant example.I can compare and contrast sympathetic to parasympathetic nervous responses.I can explain overall function of a reflex arc.AdvancedI can compare and contrast structures and functions of 3 kinds of neurons.I can provide an overview of the nervous impulse.I can provide an overview of the synaptic gap process.

28.1 - Nervous System Structure and function Nervous systems receive sensory input, interpret it, and send out appropriate commands

- Nervous systems, are the most intricately organized data-processing systems on Earth

A neuron consists of a cell body with- A ________________________ and ______________________- Long thin extensions called neuron fibres that convey signals

Two main divisionsTwo main divisions are:The ___________________________________________________ (CNS)

- Consists of brain and spinal cordThe ____________________________________________________ (PNS)

- Is mostly made up of communication lines called nerves that carry signals into and out of the ________- The ______________ also has __________________, which are clusters of neuron cell bodies

Organization of a nervous system- The nervous system obtains and processes sensory information- And sends commands to effector cells, such as muscles, that carry out appropriate responses

It is organized as - _________________________________: conduction

from sensory receptors- _________________________________: interpretation

of the sensory signals- _________________________________: is the

conduction of signals from the integration centres to the;

- __________________________________, such as a muscle or gland

Automatic responsesOur body has automatic responses called reflexesThree functional types of neurons________________________________: convey signals (information) from sensory receptors into the CNS_____________________________: Located entirely in CNS; integrate data and relay appropriate signals to other interneurons or motor neurons_______________________________: convey signals from the CNS to effector cells28.2 - Neurons are the functional units of nervous systemsNeurons are cells specialized for carrying signals and consist of- _________________________________________Two types of extensions (fibers) that conduct signals, Numerous __________________________ and ____________________________Dendrites and Axons- _________________ are highly branched extensions that receive signals from other neurons and convey this information toward the cell body- ___________________ are typically longer extensions that that transmit signals to other cells which may be other neurons or effector cells- Axons from your spinal cord to muscle cells in your feet (1m long!)

Supporting CellsSupporting cells, known as _______________ are essential for the structural integrity and normal functioning

- __________________________________________ (PNS) or Oligodendrocytes (CNS)- Covered in a ___________________________________________ (insulation)- ____________________________________: are the only point on axons where signals can be

transmitted

Nerve Signals and Their Transmission- A neuron maintains a ________________________________________ across its membrane- At rest, a neuron’s plasma membrane has an electrical voltage called the _____________________

potentialThe Resting PotentialThe resting potential

- Exists because of differences in __________________ ____________________ of the fluids inside and outside of the cell

- K+ freely flows out, leaving an excess of negative charge

- Is caused by the membrane’s ability to maintain a positive charge on its outer surface opposing a negative charge on its inner surface

28.4 - A nerve signal begins as a change in the membrane potential- A stimulus alters the permeability of a portion of the membrane allowing ions to pass through and changing the membrane’s voltage - A nerve signal, called an _____________________________- Is a change in the membrane voltage from the resting potential to a maximum level and back to the resting potential

28.5 - The action potential propagates itself along the neuron

Action potentials- Are self-propagated in a one-

way chain reaction along a neuron

- _________________________ events

- The frequency of action potentials change but not their ___________________________

- Will only change in frequency with strength in stimulus

Propagation of the action potential along an axon1. When this region of the axon (blue) has its Na+ channels open, Na+ rushes inward (blue arrows), and an action potential is generated2. Soon, the K+ channels in that same region open allows K+ to diffuse out of the axon (green arrows), Na+ channels are ____________ and inactivated. Downswing of AP 3. Short time later, no signs of an AP because axon has returned to its resting potential

28.6 – Neurons communicate at synapse- When an action potential reaches then end of an axon, it generally stops there.- Action potentials are not transmitted from cell to cell rather information is transmitted at a ______________Synapses come in two varieties- 1. _________________________________- 2. _________________________________

Electrical Synapse- Electrical synapses pass ________________

_____________________ directly from one neuron to the next

- The receiving neuron is stimulated quickly and the same frequency of action potentials as the sending neurons

- Electrical synapses are found in the __________ and digestive tract, where nerve signals maintain steady, ___________________ muscle contractions

Chemical Synapses- Chemical synapses have a narrow gap called

the ______________________________ which separates the sending neuron from the receiving neuron

- The electrical signal of the action potential is converted to a chemical signal

- The chemical signal consists of molecules called ____________________________________________ that are stored in synaptic vesicles which are secreted out into the synaptic cleft

- The neurotransmitter crosses the synaptic cleft and _____________ to a _______________________ on the surface of the receiving cell

28.7 - Chemical synapses make complex information processing possible- A neuron may receive information from hundreds of other neurons via thousands of synaptic terminals- Neurons can have ___________________________ neurotransmitters (green) and _________________________ (red) which can create more action potentials or decrease action potentials respectively. - The summation of excitation and inhibition determines whether or not a neuron will transmit a nerve signal28.8 - A variety of small molecules function as neurotransmittersMany small, nitrogen-containing molecules serve as neurotransmitters- Acetylcholine is important in the brain and synapses between motor neurons and muscle cells- They can act as both excitatory and inhibitory- Biogenic amines are derived from amino acids- These biogenic neurotransmitters are important in the CNS- Epinephrine, norepinephrine, serotonin, dopamine

Neurotransmitters ______________________ and ________________________ – affect sleep, mood, attention and learning

Imbalances lead to various disorders- Lack of dopamine – ____________________________ Diseases- _______________________ of dopamine – Schizophrenia- Reduced norepinephrine and serotonin – types of _______________________________- LSD – ‘Acid’ produces _____________________________ effects by binding to serotonin and

dopamine receptors in the brainNeurotransmitters cont’dFour amino acid based neurotransmitters in CNS

- Aspartate and glutamate – _______________________________ - Glycine and ____________________ (gamma aminobutyric acid) are inhibitory

Peptides can make neurotransmitters- Substance P – mediates our perception of ___________________________- _______________________ are both neurotransmitters and hormones – decrease pain during physical

and emotional stressDissolved gases – Nitric Oxide (NO) for E.D.28.9 Many drugs act at chemical synapsesMany psychoactive drugs act at ___________________ and affect neurotransmitter action

Animal Nervous System28.11 - Vertebrate nervous systems are highly centralized and cephalized

Skip 28.10- The spinal cord runs ____________________ inside the vertebral

column and conveys the information from the brain and integrates simple responses to certain kinds of ________________ like the knee-jerk reflex

- The brain includes the _____________________________ centers that keep the body functioning smoothly

- The brain capillaries are the most selective to allow nutrients and oxygen in and keep other chemicals out using the ______________ _____________________________

Components of the CNS- Both the brain and the spinal cord have _____________-

filled spaces- ________________________ in the

brain are continuous with the narrow canal of the spinal cord

- These cavities are filled with ___________________________ fluid, which is the formed in the brain by filtering the blood.

- Also protecting the brain are the meninges, layers of connective tissue

Gray and white matterWhite matter is mostly composed of _____________________ with their myelin sheathsGray matter consists mainly of nerve bodies and ____________________________

Cranial nerves originate in the __________________ and terminate in structures in the head and upper bodySpinal nerves originate in the ______________________________________ and extend to everything else!28.12 The peripheral nervous system of vertebrates is a functional hierarchyThe PNS can be divided into two functional components- The somatic nervous system and the autonomic nervous system- The _____________________________________ system- Carries signals to and from skeletal muscles, mainly in response to external stimuli- The _____________________________________ nervous systemRegulates the internal environment by controlling smooth and cardiac muscles and the organs of various body systems

28.13 Opposing actions of sympathetic and parasympathetic neurons regulate the internal environment

- The autonomic nervous systemThe parasympathetic division of the autonomic nervous system

- Primes the body for activities that _________________ and _________________ energy for the body -The sympathetic division of the autonomic nervous system

- Prepares the body for intense, __________________ -consuming activities

28.14 The vertebrate brain develops from three anterior bulges of the neural tube- The vertebrate brain develops from the ___________________, __________________, and ___________________________The size and complexity of the cerebrum in birds and mammals correlates with their sophisticated behavior

28.15 The structure of a living supercomputer: The human brain

The human brain is more powerful than the most sophisticated computerThe human brain is composed of three main partsThe forebrain, the midbrain, and the hindbrain

Major structures of the human brain

The Brain- The midbrain and subdivisions of the hindbrain, together with

the ___________________ and _________________________

- Function mainly in conducting information to and from higher brain centers

- Regulate ___________________________________, keep track of body position, and sort sensory information

- The forebrain’s cerebrum- Is the largest and most ______________________ part of the

brain

The Brain cont’dMost of the cerebrum’s integrative power resides in the cerebral cortex of the two cerebral hemispheres

28.16 The cerebral cortex is a mosaic of specialized, interactive regions

- Specialized integrative regions of the cerebral cortex include- The ___________________________ cortex and centers for vision, hearing, taste, and smell

- The motor cortex- Directs _________________________

- Association areas- Concerned with higher mental activities such as

reasoning and language, make up most of the _____________The right and left cerebral hemispheres

- Tend to specialize in different mental tasks

28.19 The limbic system is involved in emotions, memory, and learningThe ____________________ system

- Is a functional group of integrating centers in the cerebral cortex, thalamus, and hypothalamus

- Is involved in _______________, _________________, and ___________________