tissue that is the framework for all other tissues in organ structure
composed of specialized neurons to conduct electromagnetic signals (impulses) 3 types: sensory, motor, interneurons
central nervous system
the command center; includes brain and spinal cord
peripheral nervous system
collects info and carries out responses; includes sensory neurons and motor neurons
carry impulses to the central nervous system
carry impulses from the CNS to effectors
consist of sympathetic and parasympathetic divisions
divert activities to "housekeeping" processes such as digestion. slows overall body function (tune out, turn off) ex. calming, conserving energy, slow heart rate, digesting
diverts activities to overall heightened function during times of heightened awareness (tune-in, turn on) ex. stress situations (heart rate sped up, dilate pupils)
nerves that communicate electrically by impulses
primarily act on voluntary (conscious) activities such as skeletal muscles (by motor neurons). carry signals from skin, skeletal muscles and tendons.
involuntary and primarily act on visceral functions. Carry signals from respiratory and GI systems, cardiac muscles, and glands
conveys messages and controls some responses directly
sudden, involuntary movements of muscles in response to a stimulus
bundles of neurons that can integrate some sensory to motor functions
get info from axons and receptors (receives messages from other cells)
carries info to synapse; action potential
Neuroglia (Schwan cells):
wraps around axon and forms myelin sheath (which speeds up neural impulses)
cells life-support center
form junctions with other cells
node of ranvier
gaps in myelin sheath which help conduct nerve impulses; saltatory transmission (action potentials from one node to next)
gap between 2 neurons- transfers info between 2; 3 parts: presynaptic membrane (at terminus), the postsynaptic membrane (dendrite and cell body), and space between (synaptic cleft) - release neurotransmitter
release of neurotransmitters
action potential changes membrane potential allowing for calcium to flow in because of diffusion; increased concentration on the inside causes vesicles to fuse with membrane and by diffusion, neurotransmitters are pushed out into synaptic cleft to bind with receptor on postsynaptic membrane
strength/duration/frequency of action potential
controls amount of neurotransmitters released
An electrical difference exists across the axon plasma membrane.
Chemicals ligands that convey the message across the synapse.
The level of depolarization needed to produce action Caused by open and closing ion channels
Neuromuscular junction, exitory, depolarize
Amino acids (GABA)
inhibitory, hyperpolarize axon
regulation of sleep, emotional stress
released in areas of the brain controlling body movements + other areas
divided further into the diencephalon and telencephalon.
center for association and learning.
three categories of receptors
mechanoreceptors, chemoreceptors, and energy-detecting receptors
4 steps of converting sensory transduction
1. Stimulation, 2. transduction, 3. transmission, and 4. interpretation.
produces a graded receptor potential. A single potential or a sum of potentials may exceed a threshold to produce an action potential
Pain receptors alert the body to damage or potential damage. Nociceptors (pain)
convey duration information. (action potentials slow-but-steady over the duration of stimulus)
convey information on intensity and rate. (action potentials increase or diminish very quickly)
provide information about the relative position or movement of body parts and the degree of muscle stretching.
monitor blood pressure
Ear structure and lateral line in fishes contain ______.
detects tastes and analyzes potential food.
Sour (pH) , Salty , Sweet, Bitter, Umami
tastebuds (which are on the tongues papillae) have 5 categories:
Smell, or olfaction
involves chemoreceptors located in the upper portion of the nasal passages. Their axons connect directly to the cerebral cortex. (can identify a vast number of complex molecules)
right enters through the
iris and associated ciliary muscle
light intensity controlled by the
focuses light on the retina
rod cells and cone cells
detect shades of gray
used for visual acuity and color vision
in the _____, photoreceptors synapse with bipolar cells, which in then synapse with ganglion cells. The ganglion cells send action potentials to the brain.
where visual processing takes place
a region of the retina responsible for high acuity, each cone cell is connected to a single bipolar cell/ganglion cell,
can detect infrared radiation (heat) due to the detection done by the pit organ
sharks and duck-billed platypuses
can detect electrical currents using electroreceptors
can detect magnetic fields to navigate along
are signaling molecules carried by the blood and may have distant targets. ex. Pancreas produces insulin and insulin receptors are on cells all around the body
regulators that act locally ex. A cell releases a signal and the cells adjacent to it receive the signal.
released into the environment communicate between individuals of the same species
can act as both circulating hormones and neurotransmitters.
can be categorized as lipophilic or hydrophilic.
activate intracellular receptors.
activate receptors on target cell membranes
Anterior pituitary (adenohypophysis)
Releases regulatory factors that stimulate growth, and hormones that stimulate other endocrine glands; portal blood system carries regulatory factors from hypothalamus
oxytocin & ADH; direct nerve connection from hypothalamus
regulates basal metabolism and development. (thyroxine)
the adrenal gland
releases both protein (catecholamine) and steroid hormones.
(ex. cortisone) modulate some aspects of the immune response and maintain glucose homeostasis (ex. Cortisol).
Epinephrine and norepinephrine,
trigger "alarm" responses
primary regulators of carbohydrate metabolism.
insulin and glucagon.
crucial to circadian cycles, can control the dispersion of pigment granules and the daily wake-sleep cycles.