Endocrine System. Nervous SystemEndocrine System Both Fast Action Short-term Effects Only target...
-
Upload
elfrieda-ferguson -
Category
Documents
-
view
220 -
download
0
Transcript of Endocrine System. Nervous SystemEndocrine System Both Fast Action Short-term Effects Only target...
Endocrine System
Nervous System EndocrineSystem
Both
Fast Action
Short-term Effects
Only target cells get signal & respond
Neurons
Slow Action
Long-term Effects
All cells get signal-only target cellsrespond
Glands & Hormones
Monitor Stimuli
Process Info
Respond to Stimuli
Maintain Homeostasis
Functions include:
Sensation Integration center Reaction (Response)
A network of billions of nerve cells linked together in a highly organized manner to act as the control center of the body.
Sensation:
Monitors stimuli (inside and outside the body)
Integration:
Processes and Interprets sensory information
Response/Reaction:
Activates muscles or glands
Central nervous system (CNS) Brain & Spinal Cord
Peripheral nervous system (PNS) Cranial nerves-
neck & head
Spinal nerves- spinal cord to lower extremities
Somatic nervous system VOLUNTARY (generally) Conduct impulses from the
CNS to skeletal muscles
Autonomic nervous system INVOLUNTARY Conducts impulses from
the CNS to smooth muscle, cardiac muscle, and glands.
Sympathetic NS“Fight or Flight”
Parasympathetic NS“Rest and Digest”
These two systems are antagonistic.
Typically, we balance them to keep ourselves in a state of dynamic equilibrium.
Two cell types:
1. Neuroglia (“glial cells”)Supporting cells90% of CNS
2. NeuronsFunctional, signal-conducting cells
OVERVIEW
Glial cells
Neuron
Example: Schwann cells
• Form myelin sheaths around the larger nerve fibers in the PNS.
• Vital to neuronal regeneration
Neuroglia
The most specialized cells in animals The longest cells:
Blue Whale neuron = 10-30 meters Giraffe neuron = 5 meters Human neuron = 1-2 meters
Nervous system allows for 1 millisecond response timeNervous system allows for 1 millisecond response time
Neurons are:
2003-2004
signaldirection
myelin coating
Multiple Sclerosisimmune system (T cells) attacks myelin coating loss of signal
Multiple Sclerosisimmune system (T cells) attacks myelin coating loss of signal
Axon coated with insulation made of myelin cells
= speeds signal signal hops from node to node
330 mph vs. 11 mph
Resting potential Neuron at rest: - inside of the neuron is negative relative to the outside. - concentrations of ions attempt to balance out on both
sides of the membrane - ions cannot balance because the cell membrane allows
only some ions to pass through ion channels.
There is a charge imbalance. (The resting membrane potential of a neuron is about
-70 mV).
At rest, there are more sodium ions outside the neuron and more potassium ions inside the neuron.
Stimulus causes potential difference to move toward 0 mV.
When potential difference reaches -55 mV (threshold level), neuron will fire an action potential.
When threshold level is reached, an action potential of a fixed sized will always fire. "ALL OR NONE".
Between the opening of the Na+ channel activation gate
and the opening of the inactivation gate, a Na+ channel CANNOT be stimulated.
This is the REFRACTORY PERIOD. Action potential is unidirectional.
- Toilet handle triggers flushing. Voltage-gated channels trigger an action potential if the membrane is stimulated with enough voltage.
- If pressed hard enough, a complete flush will occur. Pushing harder on the handle will not make a bigger flush. This is true for the action potential: all-or-none.
- Flush involves movement of "materials" through plumbing.The action potential involves movement of Na+ and K+ ions through voltage-gated channels.
- The force for fluid movement in the toilet is water pressure. The ‘pressure’ for ion movement is an electrochemical gradient.
- Toilets can clog so materials cannot move.Drugs and toxins can prevent ion movement and “clog” the action potential.
Unmyelinated neurons undergo continuous chemical conduction
Myelinated neurons undergo saltatory conduction - alternating electrical conduction and chemical conduction.
In this situation, the wave of depolarization travels along the axon
Analogous to dominos falling
In unmyelinated axons:
Saltare is a Latin word meaning “to leap.”
The Myelin Sheath is segmented. There are ‘myelin-free’ regions along the axon, called the nodes of Ranvier, or Myelin Sheath Gaps.
Myelinated axons: Saltatory Conduction
1. Which do you think has a faster rate of AP conduction – myelinated or unmyelinated axons?
2. Which do you think would conduct an AP faster – an axon with a large diameter or an axon with a small diameter?
The answer to #1 is a myelinated axon. Could you move 100m faster if you walked heel to toe or if you bounded in a way that there were 3m in
between your feet with each step?
What about throwing an object?
The answer to #2 is an axon with a large diameter. Could you move faster if you walked through a hallway that was 4 m wide or if you walked
through a hallway that was 1m wide?
Junction between nerve cells 1st cell releases chemical to
trigger next cell Where drugs may affect N.S.
2003-2004
animation
1. Electrical current travels down the axon
2. Vesicles with chemicals move toward the membrane and merges with the membrane of synaptic bulb
3. Chemicals are released and diffuse toward the next cell’s plasma membrane
4. The chemicals open up the transport proteins and allow the signal to pass to the next cell
http://learn.genetics.utah.edu/content/addiction/reward/neurontalk.html
Cerebrum
Corpus callosum
Cerebellum
Thalamus
Hypothalamus
Midbrain
Pons
Medulla oblongata
Spinal cord
Functions Basic body functions:
breathing, heart, digestion, swallowing, vomiting Homeostasis Coordination of movement
The “lower brain” medulla oblongata pons cerebellum
Cerebrum2 hemispheres left controls right side of body; right controls left
Corpus callosumThe connection between the 2 hemispheres
Left hemisphere “Logic side” Language, math, logic, vision & hearing Fine motor control
Right hemisphere “Creative side” Pattern recognition, spatial
relationships, non-verbal ideas, emotions, multi-tasking
Regions specialized for different functions Lobes
Frontal: speech, control of emotions Temporal: smell, hearing Occipital: vision Parietal: speech, taste, reading
frontal
temporal occipital
parietal
Occipital lobe- visual processing
Temporal lobe-memory, sound processing, auditory stimuli
Frontal lobe- higher thought functions, judgment, personality, emotion, problem-solving, planning, movement
Parietal lobe- sensation, language (left side)
Pons- breathing, relay
Organs of the Peripheral Nervous System (PNS)
1.Nerves=a true organ (made of different tissue) and performs one functionFunction: transport nerve impulses from one part of the body to another
2. Ganglia = clusters of neuron cell bodies located outside the CNS
Reflex, or automatic response
Rapid response: automated
Signal only goes to spinal cordNo higher level processing=Does not involve brain
AdvantageDon’t need to think or make decisions about: Ex’s: Blinking, balance, pupil dilation, flinching
Accidents Drugs Alcohol Disease
Contagious Hereditary
http://learn.genetics.utah.edu/content/addiction/drugs/mouse.html
Function: Chemical regulation of bodily processes-Uses hormones
-Called ductless glands (secrete directly into bloodstream)
Chemical messengers Secreted from glands/cells- in small
amounts Travel through bloodstream Act on Target cells (receptors)
▪ Effect rates of reactions/processes▪ Enzymes rates▪ Protein synthesis▪ Transport of materials across a membrane
Negative Feedback:-Response in opposite direction of stimulus-Like a thermostat-Ex. Parathyroid hormone- Regulates Calcium levels
Ca2+ rise= stops secretion of hormone
Positive Feedback:-Response in same direction as stimulus-When positive response, signals release of moreEx. Oxytocin= Uterine contractions during childbirth
-Increase strength of contraction until birth
video
GLANDPituitary(GH, PRL, TSH, ACTH, MSH, FSH, LH)
Thyroid(T4, T3, Calcitonin)
Parathyroid(PTH)
Pineal (Melatonin)
Thymus (Thymosin)
FUNCTION Growth, Skin, Breast milk,
Metabolism, Ova, Sperm, Gonads, Fluid balance
Metabolism, Growth, Ca2+ levels
Ca2+ / Phosphate levels
Inhibit secretion of FSH and LH, animal sleep-wake cycles, other cycles
Stimulates maturation of T lymphocytes
Adrenal(Epinephrine, Norepinephrine)
Pancreas (Glucagon, Insulin)
Gonads Ovaries (Estrogen)
Testes (Testosterone)
“Flight or Fight” Response- metabolism, HR, BP
Conversion of glycogen to glucose (Glucagon) and conversion of glucose to glycogen (Insulin)
Sexual development
Estrogen: female sex characteristics, ovarian cycle, and menstrual cycle
Testosterone: male sex characteristics and sperm cell production