IRAT 3- integumentary and nervous systems Flashcards
What is the largest system of the body?
Integumentary
What are the two components of the integumentary system?
Cutaneous membrane(skin) and accessory structures
components of cutateous membrane
outer epidermis, inner dermis
dermis made up of:
dense irregular ct
subcutaneous layer(hypodermis)
loose ct
PEMPPSSDC- function of integumentary
protection, excretion, maintenance, production, production, synthesis, storage, detection, coordination
nervous tissue contains two kinds of cells:
neuroglia (glial cells) and neurons
neurons function
intercellular communication
neuroglia function
preserve structure of nervous tissue and essential to survival and function of neurons
CNS- central nervous system
- process and coordinate sensory data from inside and outside body
- higher functions of brain include intelligence. memory, learning, and emotion
- consists of nervous tissue, connective tissue, and blood vessels
PNS- peripheral nervous system
Includes all nervous tissue outside CNS
– Delivers sensory information to CNS
– Carries motor commands to peripheral tissues
afferent division
carries sensory info into
efferent division
carries motor commands; exits from processing center
- from cns to muscles, glands, and adipose tissue
Receptors
• Detect changes or respond to stimuli
• May be neurons or specialized cells
• May be single cells or complex sensory organs (e.g., eyes,
ears)
Effectors
- target organs that respond to motor commands
- efferent neurons trigger muscle to move
Somatic Nervous System- SNS
- controls skeletal muscle contractions
- both voluntary and involuntary (reflexes)
Autonomic Nervous System- ANS
Controls subconscious actions, contractions of smooth and
cardiac muscle, and glandular secretions ex: eating food and digesting
• Sympathetic division has a stimulating effect
• Parasympathetic division has a relaxing effect
Enteric Nervous System- ENS
- Initiates and coordinates visceral reflexes locally
• Without instructions from CNS - 100 million neurons in walls of digestive tract
cell body
– Large nucleus and nucleolus
– Perikaryon (cytoplasm)
– Mitochondria (produce energy)
– RER and ribosomes (synthesize proteins)
Cytoskeleton or perikaryon
– Neurofilaments and neurotubules
• Similar to intermediate filaments and microtubules
– Neurofibrils
• Bundles of neurofilaments that provide support for dendrites
and axon
Nissal bodies
– Dense areas of RER and ribosomes in perikaryon
– Make nervous tissue appear gray (gray matter)
Anaxonic neurons
- small
- found in brain and special sense organs
Bipolar neurons
- small and rare; one dendrite and one axon
- found in sight smell and hearing
unipolar neurons
• Axon and dendrites are fused; Cell body to one side
• Most sensory neurons of PNS
Multipolar neurons
- Have one long axon and two or more dendrites
- Common in CNS; All motor neurons control skeletal muscles
sensory neurons
afferent neurons
Introreceptors
•Sensory neuron
Monitor internal systems (e.g., digestive, urinary)
• Internal senses (stretch, deep pressure, pain)
Extroreceptors
•Sensory neuron
Monitor external environment (e.g., temperature)
• Complex senses (e.g., sight, smell, hearing)
Proprioceptors
- sensory neuron
Moniter position and movement - skeletal muscles and joints
Interneurons
- brain and spinal cord
- located between sensory and motor neurons
- involved in higher functions: memory, planning, and learning
Neuroglia
- support and protect neurons
- make up half the volume of nervous system
Astrocytes
- type of neuroglia
- have large cell bodies
- function to maintain blood brain barrier (BBB)
Oligodendrocytes
- type of neuroglia
- small cell bodies
- cooperate to form myelin sheath (protection)
- gray matter- unmyelinated axons
Ependymal cells
- type of neuroglia
- form epithelium that lines central canal of spinal cord and ventricles of brain
- produce and monitor cerebrospinal fluid (CSF)
Microglia
- type of neuroglia
- smallest and least numerous neuroglia
- fine-branched processes
- clean up cellular debris, wastes, and pathogens
Satellite cells
- PNS
- surround ganglia
- regulate interstitial fluid around neurons
Schwann cells
- PNS
- form myelin sheath around axons
- mylinating schwann cell sheaths only one axon
Resting membrane potential
membrane potential of a resting cell
Graded potential
- temporary change; change caused by stimulus
Action potential
- electrical impulse
- produced by graded potential
Extracellular fluid
- contains high concentrations of Na+ and Cl-
Intracellular fluid (cytosol)
- contains high concentrations of K+ and negatively charged proteins
Chemical gradients
- concentration gradients of ions Na+ and K+
Electrical gradients
- charges are serperated by cell membrane
- cytosol is negative relative to extracellular fluid
electrochemical gradient
- sum of chemical and electrical forces action on an ion across the membrane
Equilibrium potential
- membrane potential at which there is no net movement of a particular ion across cell membrane
- K+ = -90mV
- Na+ = +66mV
- Na+ has a small effect on resting potential
Sodium-potassium exchange pump
- powered by ATP
- ejects 3 Na+ for every 2 K+ brought in
- balances passive forces of diffusion
- stabilizes resting membrane potential (-70mV)
When does membrane potential change?
in response to temporary changes in membrane permeability
Passive ion channels (leak channels)
- are always open
- permeability changes with conditions
Active ion channels (gated ion channels)
- open and close in response to stimuli
- at resting , most are closed
Chemically gated ion channels
- also called ligand-gated channels
- open when they bind specific chemicals ex: ACh
- Found on cell body and dendrites of neurons
Mechanically gated ion channels
- respond to membrane distortion
- found in sensory receptors that respond to touch, pressure, or vibration
- when you touch something, you distort it
Voltage gated ion channels
- respond to changes in membrane potential
- found in axons and cardiac muscle cells
- open- (activated)
- closed- but capable of opening
- closed and incapable of opening (inactivated)
If a resting membrane is exposed to a chemical, what happens?? - 3 steps
- chemically gated Na+ channels open
- sodium ions enter the cell
- membrane potential rises
Repolarization
- when stimulus is removed, membrane potential returns to normal
Hyperpolarization
- results from opening potassium ion channels
- positive ions move out of, not into cell
- opposite effect of opening sodium ion channels
- increases negativity of resting potential
What is the threshold for axon??
- -60 to -55mV
Generation of action potentials- steps
- Depolarization to threshold
- activation of voltage-gated Na+ channels
- Na+ rushes into cytosol
- inner membrane surface changes from negative to positive
- Inactivation of Na+ channels and activation of K+ channels
- at +30mV, inactivation gates of Na+ channels CLOSE
- K+ moves OUT of cytosol
- repolarization begins = back to normal
- return to resting membrane potential (-70mV)
Refractory period
- don’t bother me , i’m busy
- during this period, membrane will not respond normally to stimuli
