Bio 224- Midterm Flashcards
(146 cards)
0
Q
Desmosomes
A
Adhering junctions that spot-rivet
-anchor cells together in tissue
-subject to considerable stretching
Cells in tissues are recognized by homophilic binding of cadherins
-a common transcriptome cells of the same tissue
1
Q
Organ
A
Body structure that integrates different tissues and carries out a specific function
2
Q
Tight junctions
A
- impermeable junctions that join the lateral edges of epithelial cells near their luminial borders
- the main group of proteins the Claudins and the Occludins
- -Associate w/ different peripheral membrae proteins located on the intracellular membrane
- -anchor the actin component of the cytoskeleton joining together the cytoskeletons of adjacent cells
3
Q
Tight Junctions and Tissue Permeability
A
- Allows precise control over the substances that can pass through a particular tissue
- Passage of materials through is regulated
- –prevents movement of materials b/t the cells
- –Form highly selective barriers that separate two compartments of highly different chemical composition
4
Q
The blood-brain barrier
A
A seperation of cirulating blood from the brain extracelluar fluid (BECF) in the central nervous system (CNS)
-consists of tight junctions around the capillaries that do not exist in normal circulation
-restrict the diffusion of microscopic objects (bacteria) and large or hydrophilic molecules into the cerebrospinal fluid
-allow the diffusion of small hydrophobic molecules (o2, CO2, hormones) and actively transport glucose
(Limits passage of particles)
5
Q
Gap Juncions
A
Communicating junctions made up of connexons
- Form (small) tunnels that permit movement of charge carrying ions and other small molecules b/t two adjacent cells
- allows passage of small materials b/t cells
6
Q
Gap junctions & Conductivity
A
- the conductivity system of the heart express high level of Gap Junctions
- the sinoatrial (SA) node
- –a group of cardiac cells on the wall of the right atrium that generate electrical impulses propagated to the myocardium in a coordinates fashion
- the atrioventricular (AV) node connects the atrial and ventricular chambers
- the bundle of His transmits impulses from the AV node to the Purkinjie fibers;
- –Provide electrical conduction to the ventricles, causing the cardiac muscle to contract at a paced interval
7
Q
The Extraxellular Matrix (ECM)
A
- Part of the connective tissue that provides structural support to animal cells
- The ECM includes:
- -the interstitial matrix
- -the basement membranes
8
Q
The Extracellular Matrix
The Interstitial matrix
A
Form the intracellular spaces filled with the gels of polysaccharides and fibrous proteins, such as collagen and elastin
-act as compression buffers against the stress placed on the ECM
9
Q
The Extracellular Matrix
The Basement members
A
Sheet-like depositions of ECM over which epithelial cells rest
10
Q
ECM is also the main components of
A
cartilages and bones
11
Q
Cell Composition of the ECM
Fibroblasts
A
- the most common cell type in connective tissue ECM
- maintain and provide a structural framework
- synthesize
- -glycosaminoglycans, proteoglycans, and glycoproteins
12
Q
Cell composition of the ECM
Chondrocytes
A
Found in cartilages, produce the cartilaginous matrix
13
Q
Cell composition of ECM
Osreoblasts
A
involved in bone formation
14
Q
Functions of ECM
A
- Support, segregating tissues from one another
- Regulate intercellular communication
- Stores a wide range of cellular growth factors that can be liberated without de novo syntheses
- Formation of the ECM is an essential process for normal body growth and wound healing
15
Q
Body Fluids
A
Plasma: the extracellular liquid of blood
Serum: plasma minus the clotting factors
16
Q
Muscle
A
consist of cells that are specialized to contract
17
Q
Nervous
A
initiate and conduct electrical signals
18
Q
Epithelial
A
protect structures and to secrete and absorb ions and organic molecules
19
Q
Connective cells
A
connect, surround, anchor and support
20
Q
Indirect (Humoral) Cell Communication
A
Mediates by chemical ligands (something that binds to another things)
-Bind to specific receptors located in target cells/tissues
Info is in general slow, and the response prolonged lasting from a few hours up to weeks
21
Q
Ligands
A
- something that binds to another thing
- binds to a receptor-very specific
- several molecules that are similar in shape, ligan will only fit/bind to specific shape
22
Q
Low affinity
A
easily detach
23
Q
high affinity
A
hard to detach
24
Hormones
- from greek word, to excite
- -signaling molecules synthesized and secreted by specialized cells that are released into the blood and exert specific biochemical actions on target cells located at distant sites
- they are produced be the endocrine glands and by teh neurons as well, which are termed neurohormones
25
Growth Factors
Hormone-like molecules released into the interstitial space exerting specific biochemical actions on target cells located at close sites
- Paracrine regulators
- Some hormones also work as paracrine regulators
26
Cytokines
Regulatory peptides:
- Historcally described in the immune system and studied outside the framework of the traditional chemical messengers
- -B/c they are not produced by specialized gland
- -Can be made by almost any body cell with another (non signaling) primary function, and are generally involved in development and immunity
- -exert a variety of local, paracrine, as well as at distance effects, like hormones
27
Neurotransmitters
signaling molecules produced by neurons that transmit signals across a synapse
-some can also have hormonal actions when are secreted into the general cirulation
28
Neural cell communication
The neuron is the functional unit of the nervous system
(it generates electrical and chemical signals)
-Neuron's chemical signals are termed neurotransmitters, which are secreted into a virtual compartment termed synpase
-the info sent by the neurons is very fast and very short lived
29
Neuromodulation
When neurotransmitter diffuse through large areas and regulate a diverse population of neurons of the central nervous system (effects wider area
-this is in contrast to classical synaptic transmission, in which on presynaptic neuron directly influences a single postsynaptic partner (only effects within the synapse)
30
Transient direct linkup of surface markers
Cells of the immune system have specialized markers on the surface membrane that allow transiently interaction with cells that have compatible markers
-phagocytes of the body's defense system specifically recognize and selectively destroy only undesirable cels, such as microbial invaders, while leaving the body's own healthy cells alone
31
Pheromones
-Are gland chemical signals released into the enviroment
-Travel through the air or water to sensory cells in another animal
Ex:
--signaling of readiness to mate
--Marking of territories
32
Circadian Rhythms
Clock found in superchiasmatic nucleus (SCN) of the brain
33
Signalling Molecules
| Hydophilic
secreted by endocrine glands, which goes directly into the blood stream
-cannot cross the membrane (need a transport tunnel)
34
Signalling Molecules
| Lipophilic
able to cross the membrane
- usually small molecules
ex: amino acids
35
Signalling Molecules
secreted by endocrine glands, which go directly into the blood stream
- Hydrophilic
- lipophilic
- Gaseous
36
Amines (amino acids)
-derived from tryosine or trypophan
-incluse thyroid hormones and some of the neurotransmitters
Noradrenalin/norepinephrine
Adrenaline/epinephrine
Serotonin
37
Proteins/peptides soluble in water
```
Circulate freely into the blood stream
-most hormones
-neurohormones
-cytokines and growth factors
EX: Insulin & Oxytocin
```
38
Steriods
-Cholesterol derivatives from the gonads & adrenal cortex glands:
--Less soluble in water use carriers
EX: Estradiol, Progesterone, Cortisol, and Testosterone
39
Retinoids
Derived from vitamin A and are mainly paracrines regulators involved in development and differentiation
40
Eicosanoids
Derivatives of fatty acids, are paracrine regulators
| -prostaglandins regulate vertebrate smooth-muscle among other effects
41
Gases as signalling Molecules
Three inorganic gasses, though normally considered toxic pollutants have now been found to be produced in animals as natural messengers
- nitric oxide, as small, highly reactive, short-lived gas molecule paracrine in many animal phyla
- carbon monoxide and
- hydrogen sulfide are paracrines
42
Cell signalling receptors
| Voltage-gated ion channels
Multimeric cell membrane bound proteins
- act through synaptic signalling on electrically excitable cells
- respond to voltage changes in the cell's membrane potentials
- open channel through the membrane for ion passage (Na+ or K+) creating electrical charges
43
Negative feedback
-after recieving the signal, a change occurs to correct the deviation by depressing it
-varibale being regulated brings about response that moves the varibale in the OPPOSITE direction
Ex: decrease in body temp leads to response that increases body temp
-also prevents responses from overcompensating
44
Positive Feedback
-Accelerate or enhance the output created by a stimulus
-Push levels out of normal range
(Rare, happens in child birth)
45
Feedforward Regulation
-Animals body begins preparing for a change in some variable before it occurs
-anticipatory
-speeds up responses and minimzes devations from the set point
-may result from or modified by learning
Ex: Dog had same response with food with the bell that was normall rang when food was coming
46
Homeostasis
- everything goes to maintain homeostasis
| - A process in which the body's internal environment is kept stable
47
Most Homeostasis is regulated by the release of hormones released from
- Hypothalamus
- Pituitary gland
- Pancreas
- Thyroid and parathyroid
- Adrenals
48
Regulators
Maintain parameters at a constant level over wide ambeint environmental variations
49
Conformers
allow the environment to determine parameters
| Ex: cold blooded animals
50
Avoiders
change their location in the environment
| Ex: birds migrating
51
Regulation of Body Temp
-Hypothalamus monitors the body temp to determine variation of normal body temp (37degrees)
52
Response to temp variation could be
- Stimulation of glands that produce sweat to reduce temp or
| - Signalling various muscles to shiver to increase temp
53
What is the advantage of homeostatic regulations? (temp)
-allows an organism to function effectively in a broad range of environmental conditions
(although it does take more energy)
54
Endotherm
an organism that produces heat through internal means, such as muscle shivering or increasing its metabolism
55
Ectotherm
An organism in which internal physiological sources of heat are relatively small or quite negligible in controlling body temp.
-rely on environmental heat sources
56
Homeotherm
Organism which maintains a stable internal body temp regardless of external influence
-temp is usually higher than enviroment
57
Poikilotherm
Organism whose internal temperature varies considerably.
| -usually the variation is a consequence of variation in the ambient environmental temperature
58
Homeostasis and blood pressure
Blood vessels can sense resistance of blood flow against the walls when blood pressure increases
- blood vessels act as the receptors and relaying this message to the brain that sends a message to the heart and blood vessels, both of which are the effectors
- the heart rate would decrease as the blood vessels increase in diameter and blood pressure would fall back into normal range
- opposite would happen when blood pressure decreases.
59
Homeostasis
| Set-point
normal value for the ligand
60
Homeostasis
| Sensor
the receptor
61
Homeostasis
| Integrator
the G proteins
62
Homeostasis
| Effector
AC
63
The Nervous System
-A network of specialized cells that coordinate functions and transmit signals between different organs
64
The Nervous System allow to exert control over the animal body too:
- sense what is going on in the outside world
- initiate actions that influence events and respond to demands, and
- regulate internal processes-all while maintaining homeostasis
65
Central nervous system (CNS) consists of:
brain and spinal cord in vertebrates
66
Peripheral Nervous system consists of:
All Neuron's & projections of their plasma membrane that are outside the CNS
67
Neurons
- Functional units of the nervous system
- Electrically excitable cell (respond to stimuli)
- Generate, send and receive information through electrical & chemical signals (to and from other cells or neurons throughout the body)
- all animals except sponges have neurons
- number varies widely as a function of size and behavioral complexity
68
Are cell membranes polarized?
yes
69
Membrane potential, transmembrane potential or membrane voltage are all
The difference in electrical charges at both sides of the biological membrane
-in excitable cells the difference is in the range of -40 mV to -80 mV
70
Transmission of Electrical and Chemical Signals
Transmitted in the form of Action Potentials
- A short lasting event in which the electrical voltage of the cell membrane rapidly rises, and fall, following a consistent trajectory (sudden change in polarity)
Action potentials occur in several types of animal cells, called excitable cells
-neurons, muscle cells, and endocrine cells as well as in some plant cells.
71
In neurons, action potentials play a central role in cell-to-cell communication:
- in neurons are also knows as "nerve impulses" or "spikes"
- a neurons that emits an action potential is often said to "fire"
In muscle cells, an action potential is the first step in the chain of events leading to a contraction
72
Neuron Structure
```
Cells body
-contains nucleus and organelles
Dendrites (receive signal) and axons (transmit signal)
-extensions of plasma membrane
Review diagram
```
73
Dendrites
Branch projections of a neuron hat conduct the electrochemical stimulations received from other neuron cells
74
Axons
- Long, slender projection of neurons
- Conducts electrical impulses away from soma
- Distinguished from dendrites by:
- -length: dendrites are resrticted to a small region around the cell body, while axons can be much longer
- -function: dendrites usually recieve signals while axons transmit them
- -axons are rich in voltage-gated ion channels
75
Synapses
Electrical stimulation is transmitted ono dendrites by upstream neurons via connections, termed synapses
-located at various points throughout the dendritic arbor
Ligand-gates channels are abundant in post synaptic membrane
76
Glial Cells or Neuroglia
- commonly know as the glue of the NS
- non-nervous cells of the NS
- in the human brain there is roughly one glia for every neuron
77
There are about two neurons for every three glia in the cerebral grey matter, they consist of:
1. Astrocytes
2. Microglia
3. Ependymal
4. Oligodendrocytes
5. Satellite cells
6. Schwann cells
78
Schwann cells
- the principal glia cells of the PNS
| - wrap around the axons of motor & sensort neurons to form myelin sheath
79
Myelin
- An electrically insulating material that forms layers around axons
- Essential for the proper functioning of the nervous system
- Composed of:
- -80% lipids, primarily the glycolipids galactocerebroside
- -20% protein:
- ---myelin basic protein (MBP)
- ---myelin oligodendrocyte glycoprotein (MOG) and
- ---proteolipid protein (PLP)
80
Node of Ranvier
Uninsulated gap formed b/t the myelin sheaths
81
Myelination
- The production of the myelin sheath; Schwann cells myelinate the PNS
- Oligodendrocytes myelinate the axons of the CNS
- --start in the fourteenth week of fetal development
- --during infancy myelination occurs quickly and does not stop until the adolescent stages of life
- --therefore, it is essential that children under the age of two receive a diet higher in fats
82
Three main types of Neurons
| Interneurons or Association Neurons
-Form interconnections b/t other neurons in the CNS
-Tend to have many dendrites
-Axons are typically short and highly branched allowing to form complex connections with other cells
Ex: breaker box
83
Three main types of Neurons
| Motor Neurons
- Efferent: send signals away from the CNS to elicit a response
- action performed
84
Three Main Type of Neurons
| Sensory Neurons
- Afferent: detect info from the outside world or internal body conditions to the CNS
- usually a large axon that bypasses the cell body and goes directly to the CNS
85
Reflex Circuits
- Neurons transmit information to each other through a series of connections that form a circuit
- A simple curcuit is a reflex arc:
- --allows an organism to respond rapidly to inputs from sensory neurons and consists of only a few neurons
- The stimulus from sensory neurons is sent to the CNS, but there is little or no interpretation of the signal
- --few interneurons are involved
- The signal is then transmitted to motor neurons, which elicit a response, such as a knee jerk
- Reflexes are among the oldest and most important features of the nervous systems:
- --exist in simple animals, such as flatworms, as well as complex mammals, such as humans
86
Reflex Arc
- Stimulus from sensory neurons sent to CNS, little or no interpretation (few to no interneurons), signal transmitted to motor neurons to elicit a response
- Quick and automatic response
87
Role of the Plasma Membrane in the Generation of Potentials
The plasma membran acts as a barrier that separates charges
-separates charge by keeping different ions largely inside or outside the cell (ion concentraton differs b/ inner and outer of the cell)
-these differences in charges act as an electrical force measured in volts
-resting potential inside cell = 70mv
(interior more neg. than exterior)
88
Membrane Factors Contributing to Resting Potential
| 1.Na+/K+ -ATPase pump
- transports 3 Na+ out for everyone 2 K+ moved in
- therefore
- -there are more Na+ outside of the cells, &
- -more K+ inside the cell
89
Membrane Factors Contributing to Resting Potential
| 2. Ion channels:
- voltage-gated Na+ channels
| - Voltage-gated K+ channels
90
Membrane Factors Contributing to Resting Potential
| 3.Negatively charged molecules
-such as proteins more abundant inside the cell
91
Depolarization (view diagram, theme 7 pg 5)
decrease in potential,
| membrane less negative
92
Repolarization (diagram, theme 7, pg 5)
return to resting potential after depolarization
93
Hyperpolarization (diagram, theme 7, pg 5)
increase in potential
| membrane more negative
94
Graded potential (diagram, theme 7, pg 5)
change in membrane potential relative to resting potential
| -depends of magnitude of stimulus
95
The Threshold Potential
The critical level at which the membrane potential must be depolarized in order to initiate action potential
(fire to maximum, or do nothing)
96
Voltage-gated K+ Channels (diagram, theme 7, pg 8)
Also termed Leaking channels:
-tend to be open more frequently at the resting membrane and
-most neurons have 50x more K+ channels than Na+ channels
Thus, at rest the membrane is more permeable to K+ than Na+
97
An inward flow of Na+
Change the electrochemical gradient & produce:
-a further fall in membrane potential
-more channels to open
-a greater electrical current:
-- this proceeds explosively until all of the available ion channels are open, resulting in a decrease in the membrane potential
--the polarity of the plasma membrane to reverse, and the ion channels then rapidly inactivate
--as the sodium channels close, sodium ions can no longer enter the neruon
(they are actively transported out of the plasma membrane)
98
Voltage-gated K+ channels & the evolution of the NS
Voltage-gated K+ channels opened 1 msec later then Na+ channels
- evolution of K+ channels w/ a slightly slower opening time than Na+ channels was a key even that led to the formation of nervous system
- if both opened at the same time, they would negate each other's effects
99
Conductivity: Role of the Nodes of Ranvier (diagram, theme 7, pg 14&15)
The only areas of the axon that have enough Na+ channels to elicit an action potential
100
Speed of the Signal Transmission varies based on:
- Axon diameter
- Myelination
- --myelinated faster than unmyelinated
- --not continuous- gaps at nodes of Ranvier
101
Synapses
Junction where nerve terminal meets a neuron, muscle cell, or gland
- presynaptic
- postsynaptic
102
Three different types of Synapses
| 1.Electrical synapse
- The presynaptic and postsynaptic cell membranes are connected
- Channels pass electrical current
- Thus, voltage changed in the presynaptic cells induce voltage changes in the postsynaptic cell.
103
Three Different Types of Synapses
| 2. Chemical Synapses: The Neurotransmitters
Endogenous agents that transmit signals from a neuron to a target cell across a synapse
-synthesized from simple precursors such as amino acids readily available (required a few biosynthetic steps)
Neurotransmitters are packaged into synaptic vesicles clustered beneath the membrane on the presynaptic side of a synapse:
-release upon an action potential at the synapse, but may follow gradded electrical potentials into the synaptic cleft.
-bind to receptors in the membrane on the postsynaptic side of the synapse
Ca+ channels allows more Ca+ to come into the cell & bind to vesicles.
104
summary of Neurotransmitter Secreation
- As an action potential reaches the end of a motor neuron, voltage-dependent calcium channels open allowing calcium to enter the neuron.
- Calcium binds to sensor protiens on synaptic vesicles triggering vesicles fusion with plasma membrane and subsequent neurotransmitter release from the motor neuron into the synaptic cleft;
- --Release it by exocytosis into the synaptic cleft
- -- Diffuses across cleft
105
Three Different Types of Synapses
| 3. Neuromuscular synapse
The presynaptic neuron releases a neuroransmitter that binds to receptors located in muscle cell.
106
The Neuromuscular Junction: The Motor Unit
- Connects the nervous system to the muscular system via synapses b/t efferent nerve fibers and muscle fibers
- Efferent nerves stimulate muscle contraction
- --Associated w/ the voluntary control of body movements
- -- Including all the non sensory neurons connected w/ skeletal muscles and skin
107
Neurons release Acetylcholine (ACh)
- A small polyatomic cation, ester of acetic acid and choline
- --diffuses through the synapse
- The only neurotransmitter in the motor division of the somatic nervous system
- --at neuromuscular junctions in skeletal muscle has an excitatory effect,
- -- in cardiac tissue has inhibitory effects (lowers heart rate)
108
ACh Binds the Nicotinic ACh Receptor (nAChR)
An ionotropic receptor located on the plasma membrane of the muscle fiber;
- Serve as ligand gate ion channels
- Binding of ACh to the NAChR depolarize the muscle fiber, causing a cascade of intracellular reactions that results in muscle contraction
109
Which neurotransmitter acts in both the peripheral nervous system and the central nervous system. As well as being the principal neurotransmitter in all autonomic ganglia
Acetylcholine (ACh)
110
What are secreted at a low level "baseline" in the absence of electrical stimulation
Neurotransmitters
- They are categorized by size, structure and function:
- --All neurons systems operate w/ combination excitatory & inhibitory actions of neurotransmitters (like brake and accelerator on a car)
111
Neural Response to Neurotransmitters
- Neurotransmitter binding to receptors change the membrane potential of postsynaptic cell
- EPSP: Excitatory Postsynaptic Potential
- --brings membrane closer to threshold potential
- IPSP: Inhibitory Postsynaptic Potential
- --takes membrane farther from threshold potential (usually hyper-polarizes)
- Synaptic signal ends when neurotransmitter broken down by enzymes or taken back into presynaptic cell for reuse.
112
Postsynaptic Potentials
a) An EPSP brought about by activation of an excitatory presynaptic input brings the postsynaptic neuron closer to threshold potential
b) An IPSP brought about by activation of an inhibitory presynaptic input moves the postsynaptic neuron farther from threshold potential
113
Synaptic integration
integrates multiple inputs to single neuron
114
Spatial summation
When two or more EPSP's or IPSP's are generated at one time along different regions of the dendrites and cell body, their effects sum together
115
Temporal summation
Two or more EPSP's arrive at same location in quick succession
116
Neuropeptides
- Small protein-like molecules (peptides) secreted by neurons as signaling molecules that influence the NS
- Involved in a wide range of brain functions including:
- --reward, food intake metabolism, reproduction, social behaviors, learning and memory
117
Neuropeptides Act as Neuromodulators
Do not cause the formation of EPSP or IPSP,
- they bring about long term changes that subtly modulate-depress or enhance- actually of the synapse
- can bind to neural receptors at non synaptic sites, & activate second messengers
- May alter the sensitivity to a neurotransmitter by causing changes in the receptor number
118
Neuromodulators may also act on presynaptic sites
- Influences the level of an enzyme critical in the synthesis of a neurotransmitter
- Delicately fine-tune the synaptic response & the effect may last for days, months, or year
- thus are involved w/ more long-lasting events such as learning & motivation
119
Evolution of the CNS
| Centralization
The evolution of longitudinal association of diffuse neuronal cell bodies into a distinct longitudinal nerve cord (for the CNS)
120
Evolution of the CNS
| Cephalization
The concentration of neurons in the head, the leading part of animals body that typically deals w/ more enviromental info than do other parts
121
The two control systems in the animal body
- the nervous system that coordinate rapid responses
| - the endocrine system that coordinate duration responses
122
Is electrical conduction faster and more precise than the diffusion of chemicals? and why?
Yes
| -it enables more rapid detection and a coordinated response to either perceived threats or available opportunities
123
What is the ultimate function of the nervous system?
to rapidly translate sensory info into action potentials
| -the NS has the advantage of providing rapid regulations over greater distances, and coordinating multiple organs
124
Ganglia
The info transmitted through one or more intermediate synapses form a ganglion
-a mass of nerve cell bodies composed mainly of the soma of cells and dendrite structures bundled or connected
Constitute the simplest form of a CNS, where signals come from more than one neuron can be integrated.
125
Do ganglia often interconnect with other ganglia?
yes
- Form a complex system of ganglia know as a PLEXUS
- -provide relay points and intermediary connections b/t the peripheral and central NS
126
The Rudimentary Brain
A highly specialized ganglion
-Have multiple synaptic connections allowed for evolution of complex control of responses
The highest integrator and regulatory center
127
The CNS
- Integrates neural info
- Coordinates the activity of all parts of the bodies
- -consists of the brain and the spinal cord
- --brain protected by the skull
- --spinal cord protected by the vertebrae
- --both are enclosed in the meninges
128
The Enteric NS
- An extensive nerve network in the wall of the digestive tract
- Controls digestive actvities w/ the ANS & hormones
- --can act independently of the rest of the NS
129
Spinal Cord
- A long, thin, tubular bundle of nervous tissue, and
- Support cells that extends from the brain via the medulla oblongata
- -transmit neural signals
- -b/t the brain & rest of the body
- -also contains neural circuits that can independently control relfexes
130
The PNS
- Consists of the nerves and ganglia located outside of the brain and spinal cord
- not protected by bones or by he blood-brain barrier
- Divided into:
a) The somatic nervous system (SNS), including the sensory systems
b) The autonomic nervous system (ANS)
131
Functions of the PNS
- Connect the CNS to the limbs and organs
- Conduct motor info, which travels down
- Conduct sensory info in the reverse direction
- Coordinates certain reflexes
132
Somatic Nervous System has Three Parts:
1) Cranial Nerves
2) Spinal Nerves
3) Association Nerves
133
Cranial Nerves
- carry info in & out of the brain stem
| - -smell, vision, eye eye muscles, mouth, vision, taste, ear, neck, shoulders and tongue
134
Spinal Nerves
-carry sensory info into the spinal cord & motor commands
135
Association Nerves
Integrate sensory input and motor output
136
The Autonomic NS
- Control system below the level of consciousness
- Controls more INVOLUNTARY visceral functions:
- --HR, digestions, respiration rate, salivation, perspiration
- --some functions work w/ the conscious mind, such as breathing
137
Divisions of the ANS
- Sympathetic division
| - Parasympathetic division
138
Sympathetic division
- fight or flight
- increases HR, faster breathing, relaxed airways
- ganglion located along spinal cord, located far away from organ
- presynaptic short, postsynaptic long
139
Parasympathetic division
- Rest and digest
- Slow HR, promote digestion
- ganglion located very close to the organ that they control
- presynaptic long, postsynaptic short
140
Cholingeric Axons
Both, preganglionic sympathetic axons and preganglionic parasympathetic axons are termed cholinergic
-Neurotransmitters: Acetylcholine
141
Adrenergic Axons
All postganglionic sympathetic are termed adrenergic
- Neurotransmitter: Norepinephrine (NE)
- -Except for the postganglionic sympathetic axons of the sweat galnds, piloerectile muscles of the body hairs and the skeletal muscle arterioles that secrete acetylcholine
142
Neurotransmitters of the Sympathetic ANS
Biogenic amines, termed catecholamines, derived from phenylalanine and tyrosine
- Epinephrine- a stress hormone released by the adrenal medulla
- -as well as a neurotransmitter present at lower levels in the brain
- Norepinephrine- involved in sleep & wake, fullness, attention, and feeding behaviour
143
The adrenal medulla is a modified (blank)
Sympathetic ganglion
- like other sympathetic ganglia is supplied by cholinergic preganglionic sympathetic fibers that secretes acetylcholine
- but the adrenal medulla secretes epinephrine & norepinephrine into the circulation
144
Circulatory Effects of Epinephrine
Epinephrine bind both, alpha and beta adrenergic receptors
-Vasoconstriction through alpha-adrenoreceptors
-Vasodilation through beta-adrenoreceptors
At high levels of circulating epinephrine, predominate the effects on alpha-adrenoreceptors
-causing vasoconstriction and an increase in peripheral vascular resistance
At low levels of circulating epinephrine, predominate the effects on beta-adrenorecptor
-producing vasodilation and a decrease in peripheral vascular resistance
145
The release of Epinephrine
Stimulation of the sympathetic branch of the autonomic nervous system prepares the body for emergencies: for fight or flight
-stimulates heartbeat
-raises blood pressure
-dilates pupils
-dilates the trachea and bronchi
-stimulates glycogenolysos (liver glycogen to glucose)
-shunts blood away from the skin and viscera to the skeletal muscles, brain, and heart
-inhibits contraction of the bladder and rectum
-inhibits peristalsis in the gastrointestinal tract
Activation of the sympathetic system is quiet general b/c single preganglionic neuron usually synapses with many postganglionic neurons
The release of adrenaline from the adrenal medulla into the blood ensures that all the cells of the body will be exposed to the sympathetic stimulation even if no postganglionic neurons reach them directly
