Nervous & Endocrine Flashcards
Glial Cells “Nerve Glue”
Support neurons physically and metabolically (4 types)
Membrane Potential
When a neuron is a rest
Resting Membrane Potential
Potential difference in a resting membrane : -70 mv in a resting neuron
membrane is polarized
Ion pumps help maintain resting potentiall
Maintaining Ion balance is expensive energetically even at rest
Electrical Signals: What are the two types?
- Graded potential
2. Action potential
What is a graded potential
If a cell is not stimulated the it is graded: signal not large enough to cause action potential.
Act as signals over very short distances
Important in initiating action potentials.
What is a action potential?
If you can feel anything that is an action. Enough stimuli are carried through to cause transfer of signal through neuron to cause an action.
Stimulus causes depolarization signal, action potential, then repolarization, then depolarized, follow by return to resting state
Structure of Neuron
Dendrites
Synapse
cell body
axon hillock
axon
Hormonal Signalling structure
Endocrine cell
Hormone receptors
Differences between Nervous and Endocrine system
Nervous Electrical impulse along defined path Receptors on postsynaptic cell Rapid signals (<1 sec) Short acting
Endocrine Hormones in blood stream Receptors on target tissues Long duration Slow signals (secs to hrs)
Similarities in Nervous and Endocrine
Both: Rely on release of chemicals Primarily regulated by negative feedback Regulate activities of cells, tissues, organs, organ systems in response to challenges to homeostasis Initiated with a stimulus Whole‐animal integration
Neuron four parts what are their function?
- Dendrites: receive input signal from other neurons.
2 Cell body: site of integration of synaptic potentials - Axon: Conduction component, propages action potentials
- Presynaptic terminals: Output (secretion of neurotransmitter.
Action potentials. what influences singling speed?
Axon diameter, larger axon faster at conducting signal
Degree of myelination-insulation
Myelination
Myelin is the sheath of the axon which increased the rate of propagation
it acts as an insulator
What is the synapse
Point of contact of a neuron with another neuron or an effector
Synaptic Transmission
Presynaptic signal (action potential) effects postynapic cell:
Rapid
excitatory or inhibitory
usually chemicals, but can be electrical
What is the difference between graded and action potentials?
Graded potentials:
- localized (polarized ) signals that do no propagate enough trigger action potentials down he neuron chain.
- Cell is not stimulated
Action potential:
-If you can feel anything that is an action. -Enough stimuli are carried through to cause transfer of signal through neuron to cause an action.
-Stimulus causes depolarization signal (graded) and if it is large enough-> action potential is triggered, then repolarization occurs and then is depolarized, follow by return to resting state.
Vertebrate Nervous System:
What are the two major parts?
Central: (CNS)
Peripheral Nervous System: (PNS)
Central nervous system: (CNS)
Brain and Spinal cord
Neurons interact to achieve integrative functions
Peripheral Nervous System: (PNS)
All process and cell bodies outside of CNS
Types of neurons: 3
Sensory neurons
• Convey information to CNS
Motor neurons
• Convey information CNS ->
effectors (i.e. muscles)
Interneuron • Found completely within the CNS • Link between sensory & motor neurons
Peripheral nervous system: Types
Somatic
Autonomic
Somatic: Outside body
Controls skeletal muscle
locomotion
Somatic sensory receptors:
Touch, hearing, vision, taste, olfaction
Autonomic: Inside body
Unobservable and Inate (ex breathing heartbeat)
Enteric-gut
Sympathetic: (ex: fight or flight response)
Parasympathetic (Rest)
Sympathetic Vs parasympathetic?
Sympathetc: (prepares body for action) Prepares body for action (heart rate, fight or flight, release of norepinephrine)
parasympathetic: (prepares body for rest and digestion)
- release of acetylcholine
Sympathetic Vs parasympathetic in regards to dive response
Autonomic conflict?
Decrease in hear rate–> parasympathetic (rest) Vagus nerve rules in diving although sympathetic action still occurs. Bradycardia controls.
Vasoconstriction, tachycardia–> sympathetic (action)
Conflict heart rate fluctuation at depth is risky (susceptibility to diving injuries). Actually not dangerous: change is action of perfusing at surface.
Parasympathetic (rest)- Vagus nerve rules in diving although sympathetic action still occurs.
benign arrhythmias are common
What are hormones and what are some effects of hormones?
Hormones are chemical messengers with regulatory effects in cells or organs.
Some affect multiple organs and some are specific to just a few targeted tissues.
Multiple: Growth hormone, Thyroid, insulin.,
Specific areas targeted: adrenocorticotropic (ACTH)
thyroid-stimulating hormone (TSH)
Pituitary Gland
“master gland”- Communicates with other gland in body
releases hormones that affect other glands
Two pieces: anterior and posterior pituitary
Controlled by hypothalamus (brain)
Adrenal glands structure
Two glands on top of kidneys: Have external cortex and internal Medulla
Adrenal gland function
Fight or flight hormones: adrenaline and nonradenalin
increases blood glucose and heart rate
Divert blood from non-essential organs
Emidiate response
Adrenal hormones produced: 3
Glucocorticoids: Cortisol- for metabolism
Mineralocorticoids: Aldosterone- mineral balance
Gonadocorticoids: Androgen and estrogen: small amounts
The main hormone form the adrenal medulla also functions as a neurotransmitter int he sympathetic nervous system. What is the name of this hormone?
Norepinephrine
What three categories of hormones are released by the adrenal cortex?
Glucocorticoids: Cortisol- for metabolism
Mineralocorticoids: Aldosterone- mineral balance
Gonadocorticoids: Androgen and estrogen: small amounts
What are Islets of Langerhans
Specialized pancreas cells that secrete:
Insulin: lowers blood sugar, stimulates protein production, amino acids
Glucagon: increased blood sugar
Diabetes Mellitus: Types and what they are:
Type 1: less common. Destruction of beta cells, do not release insulin-no glucose regulation.
Type 2: common (lifestyle). Insulin resistance–> beta cells still work but targeting cells are less sensitive
Gestational diabetes:
-usually disappears after childbirth.
What is stress? lol
Stressor:
- stimulus that threatens homeostasis
- physical and psychological
Stress response:
-achieving stability through change
Stages of stress:
Immediate:
- sympathetic (seconds):fight or flight
-sympathetic-adrenomedullary(Sam)( 20-30 seconds) takes a little longer: stimulates rapid mobilization of metabolic resources (ex. increase in o2 stores for fight or flight, redirecting of blood to important organs.
Prolonged:
-HPA-axis–>. its, hrs, wks
regulate metabolism, immune response and general homeostasis
