YummyKrackers for Bio Flashcards
What is the function of paracrine system?
local mediators (proteins, amino acid derivatives, fatty acids) are released by cells into the interstitial fluid (the autocrine and paracrine thing, not as fancy communication as the nervous system or endocrine system)
What kind of energy source does neurons use most?
Glucose! They don’t even need insulin to transport glucose in.
What is the order of neuron activation?
- Dendrites receive signal to be transmitted
- The cell body senses disturbance and notifies axon hillock.
- Axon hillock generates an action potential down axon, which may or may not have myelin sheath.
- Once at the axon terminal, a signal can be transmitted to a synapse where neurotransmitters may be released to send a signal to another dendrite or something
What is the purpose of the Na+/K+ pump on membranes of neurons?
It pumps 3 Na+ outside cell and 2 K+ into the cell
What causes hyperpolarization?
The slow potassium channels are less sensitive to voltage change and they take longer to open, after the depolarization step (now cell is + inside), but they are such slowpokes that they also take a long time to close and they let too much K+ flow out of the cell and this causes the inside of the cell to be even more negative than the resting potential.
What causes depolarization?
When voltage across the membrane is disturbed from a signal and activates sodium channels to change configuration and open -> more positive ions flow into the cell and further disturb voltage across membrane.
How are neurotransmitters released?
Actional potential at synapse activates Ca2+ to flow into the cell and this sudden influx of calcium ions cause the neurotransmitter vesicles to be released into the synaptic cleft
What is the function of acetylcholine as a neurotransmitter?
It has an inhibitory effect on the heart but an excitatory effect on visceral smooth muscle of the intestines
Myelin is made by what in each nervous system?
Oligodendrocytes in central nervous system
Schwann cells in peripheral nervous system
Also! Myelin is what causes white matter vs. gray matter. So white matter has lots of myelinated axons!
What is saltatory conduction?
Myelin speed up action potential by allowing action potentials to jump from node to node
What happens during a simple reflex arc?
- Sensory (afferent) neurons receives signal from receptor cells
- Interneuron transfer signal from neuron to neuron.
- Motor (efferent) neuron carries signal to muscle or gland, aka the effectors
Usually CNS has interneurons and PNS has sensory and motor functions
Which neurotransmitter does each autonomic nervous system usually use?
Acetylcholine is used by all preganglionic neurons in ANS and postganglionic neurons in parasympathetic system. So all of parasympathetic uses acetylcholine.
Epinephrine or norepinephrine is used by postganglionic neurons in sympathetic nervous system.
Light first strikes the eye at what part?
The cornea, and the cornea does most of the light bending
What is the function of lens in the eye?
To focus light. Ciliary muscles help contract and relax the lense. Our eyes are like converging lens.
What vitamin is good for the eye?
Vitamin A because it is a precursor to the pigment cells, rods and cones
Discuss the pupil reflex?
In bright environments, the circular muscles contract the iris to constrict the pupil and to screen out light (parasympathetic). In dark environments, the iris contracts and dilates the pupil to allow more light to enter (sympathetic).
What structure in the ear detects sound and converting it into a neural signal?
Cochlea, pressure is detected by vestibular membrane and the “hair” cells convert this to a neural signal
What structure in the ear is for maintaining balance?
Semicircular canals
What does the medulla oblongata do?
Controsl involuntary breathing movements
What is the difference between exocrine and endocrine glands?
Exocrine glands release enzymes into external environment through ducts.
Endocrine glands release hormones directly into body fluids like bloodstream
Difference between peptide hormones and steroids?
Peptide hormones are water soluble and move freely through the blood but can’t diffuse through he cell membrane of the target cell so they need to bind to a membrane-bound receptor -> either pemeability of ion channel increases or intracellular second messengers creates a cascade of events.
Steroid hormones are lipids so they require a protein transport in the blood stream but they can diffuse through the cell membrane easily and once in the cytosol they bind a receptor that brings it to the nucleus where it affects transcription levels.
Oh yeah! Also, tyrosine derivatives are either like peptides are lipids.
How is hypothalamus and anterior pituitary related?
A nerve signal tells hypothalamus to synthesize releasing or inhibitory hormones that are carried to the capillary bed of anterior pituitary and then anterior pituitary release peptide hormones (ONLY PEPTIDE hormones, no steroids)
What are the hormones released by anterior pituitary?
- hGH (growth of almost everything everything)
- ACTH (stress hormone, stimulates release of glucocorticoids at adrenal cortex )
- TSH (release T3 and T4 and increases thyroid size)
- FSH & LH (reproduction stuff)
- Prolactin (lactation, usually inhibited until needed)
