Define a negative feedback system.

Negative feedback - a change in a variable leads to a response that moves the variable opposite of the initial change

1. variable - the factor that is being regulated and is subject to change. Ex: body temperature.

2. sensor (receptor): detects changes in the variable from a set point.

3. integrating/control center - receives information from the sensors and determines a solution to the change

4. effectors - make the change given by the integrating center on the variable

A change in the variable leads to responses that movethe variable in the same direction of the initial change.

The phospholipid bilayer embedded with hydrophilic proteis.

Phosphate group - polar - hydrophilic - water soluble

Fatty acid chains - nonpolar - hydrophobic - oil soluble

This structure prevents hydropilic molecules from crossing the membrane.

What is an integral protein?

What is a peripheral protein?

An integral protein spans the entire width of the plasma membrane. (Ex: transporters, channels, receptors, carriers)

A peripheral protein is partially embedded on either side of the plasma membrane. (Ex: enzymes, structural support, receptors)

What is a glycolipid?

What is a glycoprotein?

A glycolipid is a molecule which consists of both a carbohydrate and a lipid.

A glycoprotein is part carbohydrate, part protein.

What are cilia?

What are flagella?

What are microvilli?

All of these structures seek to increase ____ __?

Cilia are short cell surface projections with motile properties. They are surrounded by the membrane and make the cells not perfectly spherical.

Flagella are long-whip like structures that do things like proper sperm. Covered by plasma membrane.

Microvilli - very small, finger-like extensions of the membrane.

Surface area.

The plasma membrane is _______ permeable.

____ molecules diffuse through the membrane while ____ molecules diffuse through the pores.

Endocytosis is?

Exocytosis is?

Selectively. Things that influence permeabilty are size, charge, and polarity.

Lipohilic molecules diffuse through the membrane, hydrophilic through the pores.

Endocytosis brings molecules into the cell.

Phagocytosis is for large molecules, pino is for smaller.

Exocytosis brings molecules out of the cell.

What is cytoplasm?

What is cytosol?

Cytoplasm is the region between the nucleus and the plasma membrane. Includes cytosol and organelles suspended in the cytosol. 

Cytosol is the fluid in which the organelles are suspended. Composed of water and other dissolved substances. Contains protein fibers like microfilaments and microtubules which function as a cytoskeleton.

Ribosomes are small granules composed of protein and RNA.

They are the site of RNA and protein synthesis. Proteins are assembled by a chain of amino acids.

What is the endoplasmic reticulum?

What is rough ER?

What is smooth ER?

ER is a site of disctribution for various cellular molecules. It's usually connected to the golgi apparatus.

Rough ER has a lot of ribosomes on its surface. Rough ER packages proteins and distributes them to other organelles.

Smooth ER has no granules on the surface and is composed of tubules. It is the site of lipid and steroid synthesis, and is sometimes responsible for storing calcium.

What is the golgi apparatus?

What are lysosomes?

What are peroxisomes?

Lysosomes are membrane bound sacs that contain digestive enzymes. Clean up wastes in the cell.

Peroxisomes are membrane bound sacs which contain enzymes to break down toxic substances in the cell. Clean up wastes.

What is the nucleus?

How is it structured?

The nucleus is the hub of genetic matierial of the cell/body.

It is surrounded by the nuclear envelope (double membrane, two lipid bilayers)

The nuclear pores join these two membranes together.

Nucleoli are dense structures which contain genes for forming RNA associated with ribosomes.

Chromatin are threadlike material composed of histone proteins.

What is the function of the nucleus?

How many chromosomes do humans have?

The nucleus is the control center of the cell; responsible for transmitting genetic information and providing instructions for protein synthesis.

Humans have 46 chromosomes, each composed of 1000s of genes.

You can make DNA from DNA through the process of ______.

You can make messenger RNA (mRNA) from DNA through the process of ______.

You can make proteins from mRNA through the process of ______.

Replication.

Transcription.

Translation. (mRNA serves as a template; tRNA helps bring amino acids to ribosome)

Cells that haven't differentiated to a specific role.

They can be collected as embryonic stem cells or as adult stem cells taken from the blood.

Fill in the hierarchy of the Central Nervous System and the Peripheral Nervous System.

Brain and Spinal Cord

 INPUT

            ______

                           _____ - visceral organs

                           _____ - sensory organs

OUPUT

        ______

                 Autonomic

                           _______ - cardiac

                          ________ - smooth glands

                  _______

                           skeletal muscle

Brain and Spinal Cord

 INPUT

            Afferent

                           Visceral - visceral organs

                           Sensory - sensory organs

OUPUT

        Efferent

                 Autonomic

                          sympathetic - cardiac

                          parasympathetic - smooth glands

                  Somatic

                           skeletal muscle

Afferent - bring information INTO the system. ex "afferent site."

Efferent - bring information OUT of the system.

The CNS consists of the brain and the spinal cord.

Cerebrum - part of the brain in charge of conscious awareness

Cerebellum - integration of afferent and efferent signals "learned movements"

Brain stem - vegetative function, afferent and efferent run through the brain stem

These are primarily nerves that project to and from the CNS.

Spinal nerves and cranial nerves.

Afferent division - sensory - transmits impulses from the sensory receptors to the CND. Types of receptors: photoreceptors, chemical receptors, pressure/touch, etc

Efferent division - motor - transmits impulses from the CNS to the effector organs

somatic nervous systems - motor neurons that stimulate contraction of skeletal muscles

autonomic nervous system (ANS) - motor neurons that stimulate contraction of smooth and cardiac muscle and glandular tissue

Neurons - specifically designed cell that transmit information using electrical impulses

glia - "supporting cells" protecting cells

Define the following phases of the Action Potential.

1 ) Resting state

2) slow rising state

3) rapid rising state

4) repolarization

5) hyperpolarization

1) ions moving through the passive channels to maintain resting potential

Na+/K+ ATPase maintains concentrations

2) stimulus depolarizes the membrane by acting on chemically-gated channels (or mechanically, temperature, etc) resulting in Na+ moving into the neuron. If the threshold value is reached, an action potential will be initiated.

3) Once threshold is reached, many more voltage-gated Na+ channels open. This process continues until action potential peaks via positive feedback.

4) voltage gated Na+ channels close via inactivation. Na+ begins to diffuse away from membrane and are pumped out of neuron. Voltage-gated K+ channels open and as K+ leads, the neuron is repolarized.

5) voltage-gated K+ channels remain open for a brief period of time after the neuron reaches its resting potential

Action Potentials are ___ or ___, meaning it can occur maximally or not at all. 

If a stimulus is strong enough to depolarize the membrane to _____, then an AP will be generated, and each one will always be the same ____.

Stimulus strength is indicated by the ______ of APs. With a ____ stimulus, there will be an increase in the frequency of APs.

All or nothing.

Threshold. Amplitude.

Frequency. Greater/Larger.

What is a refractory period?

What is an absolute refractory period?

What is a relative refractory period?

A refractory period sets an upper limit for maximum frequency.

An ARP is the period of time during an AP when the membrane will not respond to a second stimulus - inactivation of Na+ channels

Another AP cannot be generated until the preceding one is finished.

A RRP is the period of time during an AP when a second AP can be produced, but only which a must stronger stimulus.

1. stimulus depolarizes membrane to produce AP

2. positive charges are conducted to an adjacent region of the membrane

3. adjacent membrane regions are depolarized to produce another AP; however, the membrane area that just produced an AP is now refractory and cannot produce another AP

Define the structural units of the neuron.

1. cell body (soma) - 

2. dendrites - 

3. axon (hillock, terminal)

4. synapse

5. tract/nerve

1. cell body (soma) - enlarged portion of the neuron which contains the nucleus and other organelles

nuclei - a group of cell bodies within the CNS

ganglia - a group of cell bodies within the PNS

2. dendrites - branched processes that extend from the cell body, afferent

3. axon - a single process that extends from the cell body, efferent

axon hillock - site where an AP is most likely to occur, occurs right after the cell body on the neuron

axon terminals - end of the axon

4. synapse - the gap between neurons

5. tract - a group of axons in the CNS

nerve - a group of axons in the PNS

Describe the following classifications of neurons:

Pseudounipolar 

Bipolar

Multipolar

Pseudounipolar - usually sensory nerves, found in a ganglia

cell body hangs off an axon with two dendritic branches 

Bipolar - rare, found in the eye

cell body is found between two axons/ two dendritic brances

Multipolar - most neurons

cell body is directly connected to dendrites and axon

sensory/afferent neurons carry information from the sensory receptors to the ____

motor/efferent neurons carry info from the CNS to the ___ _____

interneurons are found within the CNS and connect the ____ and ____ neurons

to the CNE

to the effector organs

afferent and efferent neurons

What are Schwann cells and what do they do?

What are nodes of Ranvier and what occurs at them?

What are satellite cells?

These are all supporting cells within the _____ nervous sytem.

Schwann cells wrap around the axons to form the MYELIN SHEATH, they protect the axons

Nodes of Ranvier are the spaces between the Schwann cells; where action potentials are conducted 

Satellite cells surround the neuron cell bodies within ganglia in the PNS

Peripheral nervous system.

Supporting cells of the CNS are called ____

What are oligodendrocytes and what do they do?

What are microglia and what do they do?

Astrocytes?

Ependymal cells?

They are called glia.

oligodendrocytes are similar to Scwann cells but they form a myelin sheath around axons of the CNS

microglia - phagocytes that help to get rid of foreign substances in the CNS

astrocytes help to maintain a normal external environment around neurons; maintain the blood brain barrier

ependymal cells - line the cavities of the brain and spinal cord, make cerebrospinal fluid (CSF)

At rest, a neuron has an excess of positive charges on the ______ of the membrane and an excess of negative charges on the _____.

A negative resting membrane potential indicates that the inside of the cell is more ___ than the outside.

The concentration of (Na+/K+) is greater inside the cell, while the concentration of (Na+/K+) is greater outside the cell.

Outside, inside

negative

Potassium, Sodium

At RMP, ___ is 75x more permeable than ___

Potassium moves ___ to ___ the cell

When this happens, the interior is left with a ____ charge

Potassium, sodium 

inside, outside

negative

The sodium/potassium pump's official name is ______.

It pumps _ Na+ out for every _ K+ in.

The pump maintains the _____ _____ for these ions.

Sodium/Potassium ATPase

3, 2

concentration gradients

Define depolarization.

Define hyperpolarization.

Define repolarization.

Resting membrane potential for a sensory neuron is ___ mV.

Depolarization is when the membrane potential becomes less negative/more positive.

Hyperpolarization is when the membrane potential becomes more negative/less positive.

Repolarization is a return to RMP.

RMP = -70mV

If K+ permeability is increased, the membrane is _____.

If Na+ permeability is increased, the membrane is ____.

If intracellular K+ is decreased, the membrane is ___.

The membrane is hyperpolarized.

The membrane is depolarized.

The membrane is depolarized.

Types of Integral Proteins

Define passive integral proteins.

Define chemically-gated channels.

Define voltage-gated channels.

Ion channels that are always open and allow ions to move down a concentration gradient.

Open when a substrate binds to a receptor on the channel and allows ions to move down their concentration gradients.

Open or close when they detect a change in membrane potential.

Conduction velocity is proportional to the ____ of the axon.

Conduction velocity increases in a _____ axon.

APs occur at the ____, the spaces between the myelinated regions of the axon.

Define saltatory conduction.

Diameter.

myelinated axon

Nodes of Ranvier

saltatory conduction - conduction of an AP from one Node of Ranvier to the next

What is a synapse?

In an electrical synapse the ____ signal is directly trasmitted between one cell to another.

Adjacent cells are joined together by ____ ______ (_____) that permit direct passage from one cell to the next.

Gap junctions conduct signals _________.

Electrical synapses found primarily in ____ and ____ muscle. 

A synapse is a functional connection between a neuron and a second cell. 

Electrical. 

gap junctions (connexins)

Gap junctions direct signals bidirectionally.

Electrical synapses found primary in smooth and cardiac muscle. 

A chemical synapse is where an electrical signal is changed into a chemical signal (a neurotransmitter) which diffuses across the extracellular space between two cells. 

Transmission is unidirectional across a synapse - goes from the presynaptic to the postsynaptic cell.

There are special receptors on the postsynaptic membrane and special mechanisms to change the chemical signal back into an electrical signal. 

In chemical transmission of electrical signals:

1. Action potential reaches the presynaptic terminals.

2. Depolarization activates voltage gated _____ channels resulting in an influx of _____ into the presynaptic terminal. 

3. Calcium triggers the fusion of the synaptic _____ (which can contain 10,000 molecules of neurotransmitter) wih the axon membrane leading of the release of neurotransmtters into the synaptic ____ via exocytosis.

2. calcium, calcium 

3. synaptic vesicles, synaptic cleft

What is a synaptic cleft?

How do substances cross the cleft?

A synaptic cleft is the space between the presynaptic cell and the postsynaptic membrane, about 30-50 nm. Even though this gap is small, this can take a millisecond to happen.

Substances cross the cleft because of diffusion.

Postsynaptic mechanisms for chemical transmission -

1. neurotransmitters move across the synaptic cleft and bind to ____ on the postsynaptic membrane.

2. chemically gated _____ or ____ channels open, allowing ions to flow through which generates electrical signal

3. _____ ______ ____ (EPSPs) - small polarizations of the membrane usually due to the influx of sodium

A single EPSP changes the membrane potential only a few millivolts which can't produce an AP; however, EPSPs can summate to threshold. 

1. receptors

2. sodium, potassium

3. Excitatory PostSynaptic Potentials

Termination of Synaptic Transmission (How the body gets rid of neurotransmitters from the receptor)

1. neurotransmitters dissociates from the receptor and _____ away from cleft

2. neurotransmitters are taken back into the presynaptic terminals via _____

3. degrading _____ break down neurotransmitters

1. diffuses away

2. reuptake

3. enzymes

Acetylcholine (Ach) as a neurotransmitter

1. first _____ identified 

2. stored in ____; released from _____ terminals into the synaptic cleft

3. binds to specific receptors on the postsynaptic cell which are

a. ______ - binds with Ach and nicotine

b. ______ binds with ach and muscarin

4. is degraded by an enzyme called _______ (AChE)

1. first neurotransmitter identified

2. stored in vesicles; released from presynaptic terminals

3. Nicotinic, muscarinic

4. acetylcholinesterase 

What is a nerve?

What is a ganglia?

A nerve is a group of axons in the peripheral nervous system.

A ganglia is a group of neuron cell bodies in the peripheral nerous system.

What is the autonomic nervous system?

Sympathetic - "____ or ____"

parasympathetic - "____ and _____"

The system responsible for involuntary activity.

Fight or flight.

Rest and digest.

Arrangement of the Autonomic Nervous Stem (ANS)

Consists of 2 neurons that connect the CNS to the effector cells.

preganglionic fiber - this neuron has it cell body in the ____ and synapses with the second neuron at an autonomic ganglion outside of the ____

postganglionic fiber - this second neuron extends from the autonomic ganglion to the ____ cells

CNS, CNS

effector

Neurotransmitters associated with SNS and PNS

1. all preganglionic neurons release _____

these are called ____ fibers

2. postganglionic neurons:

PNS - release ___

SNS - primarily release _____

called ______ or _____ fibers

1. all preganglionic neurons release acetylcholine

these are called cholinergic fibers

2. PNS - releases ACh

SNS - primarily releases norepinephrine (NE)

called adrenergic or catecholaminergic

Receptors

1. cholinergic recepters (activated by ___)

a. nicotinic receptors (N) located on ____ and ____ postganglionic neurons

b. muscarinic receptors (M) found on effector cells stimulated by parasympathetic postganglionic neurons

2. adrenergic receptors (activated by ____ and ____)

a. found on effector cells stimulated by ____ postganglionic neruons

b. ____ receptors (a1 and a2)

____ receptors (b2 and b2)

1. cholinergic receptors (activated by ACh)

a. located on sympathetic and parasympathetic postganglionic neurons

2. adrenergic receptors (activated by norepinephrine and epinephrine)

a. simulated by sympathetic postganglionic neurons

b. alpha

beta

Autonomic Regulation of Specific Organs 

PNS - "rest and digest"

associated with conservation of energy and maintenance of organ function durning times of minimal activity

SNS - "fight or flight"

prepares the body for responding to fear, stress, etc

Autonomic Regulation of Specific Organs

1. Heart

PNS - ___ from the postganglionic neuron binds to ____ receptor

*decreases heart ___

*decreases force of ____

SNS - ____ binds to ____ receptors

*increases heart ___

*increases force of ____

1. Heart

PNS - ACh from the postganglionic neuron binds to muscarinic receptor

*decreases heart rate

*decreases force of contraction

SNS - norepinephrine binds to beta-2 receptors

*increases heart rate

*increases force of contraction

Autonomic Regulation of Specific Organs

Lungs

a. PNS - ____ on and ____ receptor

*contracts bronchial muscle - _____ the airways

b. SNS - _____ on a ____ receptor

*relaxes _____ muscle

GI Tract

a. PNS

*Increases motility

*increases secretions

b. SNS

*decreases motility

*decreases secretion but may increase ____

Lungs

a. PNS - ACh on and muscarinic receptor

*contracts bronchial muscle - constricts the airways

b. SNS - Norepinephrine on a beta-1 receptor

*relaxes bronchial muscle

GI Tract

a. PNS

*Increases motility

*increases secretions

b. SNS

*decreases motility

*decreases secretion but may increase mucus

Autonomic Regulation of Specific Organs

4.  Blood Vessels

a. PNS

·         no direct innervation of vascular (around arteries and veins) smooth muscle

b.     SNS alpha receptor

·         constriction of most blood vessels

·         dilation of blood vessels that supply the skeletal muscles

Eye

a.       SNS – dilate pupil

b.      PNS muscarinic – constrict pupil

Normal control is mostly PNS – so blocking causes…

4.  Blood Vessels

a. PNS

·         no direct innervation of vascular (around arteries and veins) smooth muscle

b.     SNS alpha receptor

·         constriction of most blood vessels

·         dilation of blood vessels that supply the skeletal muscles

Eye

a.       SNS – dilate pupil

b.      PNS muscarinic – constrict pupil

Normal control is mostly PNS – so blocking causes…