Week 9 Flashcards
Endocrine cells
secretes hormones into blood
Nerve and endocrine cells - interaction
work together to ensure proper functioning of body system
Nerve and endocrine cells - communication
most intercellular communication takes place by chemical signals that travel to another cell
Target cell
cell that signal molecules bind to in order to trigger response
Nerve control
fast and quick
impulses are delivered to highly defined target cells
Endocrine control
slow and last a long time in the blood, can alter gene transcription
broadcast to all cells potentially
Nervous system functions
controls movement of skeletal muscles
Endocrine system function
controls prolonged activities
Paracrines
chemicals secreted by one cell that affects neighbouring cells
Autocrines
chemicals that are secreted into intercellular fluids that diffuse to receptors on very same cell
Hormones
carried throughout the body by blood circulation
Neurotransmitters
move across the synaptic cleft, secretion may be controlled by impulses that originated far from release site
Pheromones
released into environment and affect other individuals
Exocrine glands
secrete substances into a duct or body cavity
Endocrine cells
secrete substances into blood
Hormone
chemical substance, secreted into blood by endocrine cells that regulate the function of other cells
act at very low blood concentrations
Neurosecretory cells
resemble neurons
propagate action potentials
cell bodies are in CNS
direct interface between nervous and endocrine system
Nonneural endocrine cells
stimulated to secrete hormones by other hormones
Peptide and protein hormones
water soluble and easily transported in blood
packages in vesicles and released to blood by exocytosis
cant cross cell membrane
Steriod hormones
synthesised from cholestrol lipid soluble, bound to carrier proteins in blood
Amine hormones
modified amino acids
may be lipid soluble or water soluble `
Hormone binding - on target cell surface
binds to part of the receptor protein outside membrane
many receptors are G protein linked
G protein linked receptors
initiate second messenger signaling cascades inside target cell
Hormone binding - inside target cell
lipid soluble hormones can diffuse through cell membrane
Negative and positive feedback effect on receptor proteins
can influence number of receptor protein per cell
negative feedback stabilizes concentration of hormones
Hormones - different cells
can have different effects
Peptide hormones - timing
synthesised prior to use and stored, can be released quickly
Steroid hormones - timing
usually synthesised on demand, initiation of secretion is slow
How hormones are removed from blood
liver and kidneys can degrade hormones enzymatically, or hormones are excreted
Peripheral activation
hormones are converted to more active forms after they are secreted
Pituitary gland
master gland
secretes hormones that control other glands
Posterior pituitary
extension of brain, hormones are synthesised and secreted by brain neurosecretory cells
Hypothalamus hormones
antiduirectic
oxytocin
antidiurectic hormone
controls water excretion of kidney
oxytocin
stimulates uterine contractions during birth and milk flow
Anterior pituitary - cells
hormones are synthesised by nonneural endocrine cells
Tropic hormones
tropins that control other endocrine glands
Adrenocorticotropin
controls adrenal cortex
Thyroid stimulating hormone
controls thyroid gland
LH and FSH
control gonads
Anterior pituitary hormones
Adrenocorticotropin Thyriod stimulating Lh FSH Growth hormone prolactin melanocyte stimulating
Growth Hormone
promotes growth
Melanocyte stimulating hormone
changes skin colour cells in amphibians
Hypothalamo - hypophysial portal system
controls that secretion of anterior pituitary hormones
Neurosecretory cells in hypothalamus
secrete hormones into blood capillaries in hypothalamus
Neurohormones from hypothalamus
releasing hormones
inhibiting hormones
Negative feedback control
concentration of hormones secreted by target glands provides information to hypothlamus to increase or decrease production of hormones
Neurons
excitable cells that generate and transmit electrical signals
make contact with target cells
Cell membrane polarity
electrical
outside is more positive than inside
Action potential
electrical signals
state of reversed polarity
Synapse
cell to cell contact point specialised for signal transmission
dendrites
carry signal to cell body
cell body
contains nucleus and organelles
axon
conducts action potentials away from cell body
Presynaptic axon terminals
make contact with other
Glial cells
not excitable
help orient neurons toward their target cells
provide metabolic support for neurons
regulate composition of extracellular fluids and perform immune function
assists signal transmission across synapse
Oligodendrocytes
glia that insulate axons in brain and spinal cord
Schwann cells
insulate axons in nerves outside brain and spinal
myelin
nonconductive sheath
white matter
myelin coated axons
grey matter
areas of cell bodies
Current
flow of electric charges from place to place
current is based on flow of ions
Voltage
exists if positive charges are concentrated in one place and negative charges are concentrated in different place
Membrane potential
voltage across membrane
can change rapidly
Resting potential
-60 mV
negative means that inside cell is electrically negative relative to outside
potassium channels are open
Sodium potassium pump
uses energy from ATP to move 3 Na ions to outside and 2 K to inside
Action potential
rapid large change in membrane potential that reverse membrane polarity
only travels in one direction
Refractory period
after action potential, Na channels cannot open again for a brief period of time
cant depolarise
Nodes of Ranvier
gaps where axon is not covered by myelin
Chemical synapse
narrow space between cells that an action cannot cross
Electrical synapse
cells are joined by gap junctions where cytoplasm is continuous; signal cross with no delay
Neuromuscular junctions
chemical synapses between motor neurons and skeletal muscle cells
Neurotransmitter types
amino acids
biogenic amines
peptides
Centralisation
integrating neurons clustered together in centralised organs
Cephalisation
major integrating areas became concentrated towards anterior end of animal
CNS
brain and spinal cord
composed of mostly neurons and glial cells
interact with sensors and effectors
Effectors
cells and tissues that perform actions to carry out orders
PNS
neurons outside CNS
brings sensory information from sense organs to CNS and carry orders from CNS to effectors
Interneurons
neurons confined to CNS
Sensory neurons
sensory receptor cells or neurons that carry signals from sensory cells to CNS
Efferent neurons
convey signals from the CNS to muscles or other effectors
Motor Neurons
carry signals to skeletal muscles
Autonomic nervous system
controls effectors other than skeletal muscles
Vertebrate ANS divisions
enteric
sympathetic
parasympathetic
Enteric division
nerve cells internal to gut wall
Sympathetic
fight or flight
parasympathetic
rest and digests
ganglion
axons of preganglionic neurons synapse on second neuron outside the CNS in collection of nerve cell bodies
Sympathetic neurontransmitter
postganglionic - norepinephrine
preganglionic - acetylcholine
Parasympathetic neurontransmitter
preganglionic and postganglionic - acetylcholine
Spinal reflex
afferent information converts to efferent activity without going through the brain
Cerebral cortex
outer most layer of cerebral hemisphere
Testosterone
steroid excreted by testes and ovaries
levels correlated with aggression and territorality
Oestrogen
main female hormone
controls menstruation and cycle
parental behaviour
Oxytocin
immediately prior to birth
stimulates uterus to contract
elicits maternal behaviour
corticosteriods
steroids produced by adrenal cortex
involved in stress response, immune reaction
rapid expression
Forebrain
ceberal cortex
cerebrum
thalamus
hypothalamus
Midbrain
tectum and tegmentum
Hindbrain
pons
medulla oblongata
cerebellum
frontal lobe
movement and planning
parietal lobe
sensory input
temporal lobe
language and memory
Occipital lobe
vision
Left hemisphere
linear thinking mode
Right hemisphere
holistic thinking mode