Midterm 1 Flashcards
What is Dementia?
A group of disorders that affects memory, thinking, and interferes with daily life.
What are the two types of dementia?
Irreversible and Reversible
Dementia is more likely to be:
Irreversible
What are the types of irreversible dementia?
Alzheimer’s, dementia with Lewy bodies, fronto-temporal dementia, vascular dementia, Parkinson’s disease, traumatic brain injury
What are the types of reversible dementia?
Depressive pseudodementia, metabolic problems, medication side effects, infections, dementia due to structural lesions
Since the elderly population is growing:
it increases the number of people who will develop dementia
Hydrocephalus
Water on the brain, enlargement of ventricles with cerebrospinal fluid. This crushes brain tissue causing a variety of symptoms.
Microcephaly
Heads are much smaller
What are the problems linked with microcephaly?
Seizures, developmental delay, intellectual disability, problems with movement and balance, feeding problems(swallowing), hearing loss and vision problems.
Anencephaly
Severe case of microcephaly where baby is born without a brain.
Major subdivisions of the brain
Cerebral cortex, thalamus, hypothalamus, midbrain, pons, medulla, cerebellum and spinal cord
Sensory neurons
Bring information to the central nervous system
Interneurons
Associate sensory and motor activity in the central nervous system (process information and decides what to do)
Motor neurons
Sends signals from the brain and spinal cord to muscles or glands
Sagittal plane
Goes right in-between eyes, splits hemispheres
Coronal plane
From ear to ear, shows both hemispheres
Horizontal plane
Horizontal slices
Central nervous system (CNS)
Composed of the brain and spinal cord
Peripheral nervous system (PNS)
Composed of nerves and ganglia(conveys information to and from the spinal cord)
What does the nervous system do?
Coordinates movement, touch, pain and our senses. Also forms our emotions, thoughts and consciousness.
What does the spinal cord do?
Conveys information from the brain to the PNS via spinal nerves.
What are peripheral nerves?
Receives and sends information from the brain to the PNS via spinal nerves
What are the two clumps of nerves that each vertebrate contains and what do they each do?
Dorsal clump which receives sensory information and the ventral clump that sends signals to muscles
Cervical segment in the spinal cord:
8 segments that innervate the back oof head, neck, shoulders and arms
Thoracic segment of the spinal cord:
12 segments that innervate thorax, upper abdomen
Lumbar segment of the spinal cord:
5 segments that innervate the pelvic girdle and the legs
Sacral regions segment of the spinal cord:
5 segments innervating urogenital and perianal structures and back of legs
Dermatomes
Region of skin that a spinal nerve innervates. Appear as horizontal slices across the body
What do spinal nerves do?
Spinal nerves innovate the body. Carry information to specific areas of the body ( such as movement orders) and receive information (such as touch, pain, etc.)
Cranial nerves
Innovate the face and mainly originate in the medulla
Where does the brain and brain stem connect?
At the medulla which is part of the brain stem
What is locked in syndrome?
Rare neurological disorder characterized by the complete paralysis of voluntary muscles in all parts of the body except for those that control eye movement.
How does locked in syndrome occur?
Traumatic brain injury, stroke, disease that destroys the myelin sheath surrounding nerve cells or medication overdose
What happens to individuals with locked in syndrome?
Conscious and can think and reason, but are unable to speak or move. Leaves them mute and paralyzed
What does the blood brain barrier do?
Separates the blood from the brains own fluid called cerebrospinal fluid (CSF)
Why is the BBB important?
Stops infections and toxins from reaching the brain
What kinds of molecules can and cannot cross the BBB?
Large molecules cannot cross the BBB easily (major hurdle for developing drugs for brain disorders). Small molecules and lipid soluble molecules can cross
What is cerebrospinal fluid(CSF)?
It is filtered from blood. Central canal of the spinal cord and the ventricles of the brain are hollow and filled with cerebrospinal fluid
What does CSF do?
Functions to cushion the brain and spinal cord. Protects neurons. Brain is buoyant in fluid since it is dense
Lumbar punctures
CSF can be drawn from the spinal column for diagnostic purposes or for the delivery of drugs to reach the CNS.
What is a cell?
simplest collection of matter that can live
Eukaryotic cells
Has a large size which makes it difficult for molecules to diffuse across the entire cell. Solved by breaking the volume into several smaller membrane bound organelles
What are the two advantages that the compartmentalization of eukaryotic cells offer?
- separation of incompatible chemical reactions
- Increase the efficiency of chemical reactions
Nucleus function:
Information storage and processing (contains the cells chromosomes)
Ribosomal RNA synthesis (in the nucleolus)
Rough endoplasmic reticulum function:
Ribosomes associated with the rough ER synthesize proteins. New proteins are folded and processed in the rough ER lumen
Smooth endoplasmic reticulum function:
Enzymes within the smooth ER may synthesize fatty acids and phospholipids or break down poisonous lipids. Reservoir for Ca2+ ions
Golgi apparatus function:
Processes, sorts and ships proteins synthesized in the rough ER. Membranous vesicles carry materials to and from the organelle
Ribosomes function:
Protein synthesis
Lysosome function:
Used for digestion and waste processing
Mitochondrion function:
ATP production
Cytoskeleton function:
Composed of protein fibers which gives the cell shape and structural stability and aids cell movement and transport of materials within the cell. (Organizes all of the organelles and other cell structures into a cohesive whole)
Plasma membrane function:
Selective barrier that allows sufficient passage of oxygen, nutrients and waste to service the volume of every cell
What are neurons?
Cells that transmit electrical signals used in communication. Muscles can respond to electrical signals by contracting.
Where are most of a neurons organelles located?
The cell body
What are dendrites?
Highly branched extensions that receive electrical signals from other neurons
What are axons?
Longer extension that transmits signals to other cells at synapses
What is the axon hillock?
Where an axon joins the cell body
What is the flow of signal in a neuron?
Dendrites–>Cell body–>Axon
Where do neurons form networks for information flow?
Synapses
What is a synapse?
Junction between an axon and another cell (gap)
What is a synaptic terminal?
Where an axon passes information across the synapse in the form of chemical messengers called neurotransmitters
The plasma membrane is impermeable to:
Charged ions, such as Na+, K+, Cl-, Ca2+
Plasma membranes contain protein channels and receptors that:
Let specific charged ions across the plasma membrane which gives neurons electrical energy
What causes a neuron to rapidly signal?
The flow of charged ions going across the plasma membrane which gives neurons electrical energy
What causes a difference in electrical potential or voltage?
A difference in electrical charge between any two points
What happens when the positive and negative charges on ions that exist on the two sides of a plasma membrane don’t balance each other?
The membrane will have an electrical potential
What is a membrane potential?
When an electrical potential exists on either side of a plasma membrane, the separation of charges is called a membrane potential
What does Na+/K+-ATPase import and export?
Imports K+ and exports Na+
Where is the concentration of K+ and Na+ ions higher?
K+ ions are higher inside of the cell and Na+ ions are higher outside of the cell
What how is information transmitted between cells?
Transmitted from a presynaptic cell(a neuron) to a postsynaptic cell(a neuron, muscles or gland cell)
What are most neurons nourished or insulated by?
Glia cells
What are astrocytes glia?
Restricted to the CNS
Maintain appropriate chemical environment for neuronal signaling
Part of the BBB to restrict what can gain access to the brain
What are oligodendrocytes glia?
Found in the CNS and are glia that form the myelin sheaths around the axons of many vertebrate neurons
What are Schwan cell glia?
Found in the PNS and form the myelin sheaths around the axons of many vertebrate neurons
What are most brain tumors caused by?
Gliomas or Meningiomas (glia cell types)
What are action potentials?
All or none changes in membrane potential that serve as electrical signals.
During an action potential, an inflow of sodium ions is followed by an outflow of potassium ions
What is the resting potential?
The membrane potential of a neuron not sending signals
How does the sodium-potassium pump maintain K+ concentration higher inside the cell and Na+ concentration higher outside of the cell gradient across the plasma membrane?
With the use of ATP
What do concentration gradients represent?
Chemical potential energy
What do resting membrane potentials do?
Sets up concentration gradients for Na+ and K+
What is the voltage difference across the plasma membrane?
-70mv
When do voltage gated ion channels open and close?
In response to stimuli
What happens at the resting potential at voltage gated Na+ channels?
The channels are closed (pos charged outside and neg charged inside)
When do voltage-gated channels open?
Conformational changes open channels when the membrane is depolarized(loss of difference in charge inside and outside of the cell) (pos & neg inside and outside cell)
Why are voltage gated potassium channels important?
Important for restoring membrane potential following depolarization
Opens slowly causing delayed efflux of potassium
Why are voltage gated sodium channels important?
Important for depolarizing membrane (making inside more positive) during action potentials
Opens rapidly allowing influx of sodium
Why are voltage gated calcium channels important?
Opens when membrane depolarizes and lets calcium flow into cell
Important for synaptic release
What happens during an action potential?
Depolarization reaches threshold (-55mv)
All or non response
Action potential is nerve impulse or signal that carries info along axon
Why can’t a second action potential be initiated during the refractory period?
Because of the temporary inactivation of the Na+ channels?
How do action potentials travel long distances?
By regenerating itself along the axon
At the site where the action potential is generated (at the axon hillock), an electrical current depolarizes the neighboring region of the axon membrane
What prevents the action potential from travelling backwards?
Inactivated Na+ channels behind the zone of depolarization (refractory period)
Which way do action potentials travel?
In one directions, towards the synaptic terminals
What causes the speed of an action potential to increase?
The axons diameter
What is the myelin sheath?
Stuff that axons are insulated with which causes an action potentials speed to increase
Where are action potentials formed?
Nodes of Ranvier
What are nodes of Ranvier?
Gaps in the myelin sheath where voltage-gated Na+ channels are found
What is saltatory conduction?
When action potentials in myelinated axons jump between the nodes of Ranvier
What happens at electrical synapses?
Electrical current flows from one neuron to another
What happens at chemical synapses?
A chemical neurotransmitter carries information across synaptic cleft(gap btw 2 cells)
What kind of synapses are most synapses?
Chemical synapses