secretes hormones that coordinate slow, long responses.

a.) reproduction

b.) development

c.) energy metabolism

d.) growth

e.) behavior

1.) hormones: secreted by endocine glands and travel thru bloodstream. they regulate growth, development, and reproduction.

2.) local regulators: secreted by paracrine and actocrine glands, travel short distances by diffusion. they regulate BP, nervous system function, and reproduction.

3.) neurotransmitters: secreted by neurons and travel short disatnces by diffusion. regulate sensation. memory, cognition, and movement.

4.) neurohormones: secreted by neurons in the brain and travel thru bloodstream.

5.) pheromones: released outside body and used to communicate with other indiv. in the species. mark the trails to food sources, warn of predators, attract mates.

1.) water-soluble: bind plasma membrane protein receptors on target cell plasma membranes

2.) lipid-soluble: diffuse thru plasma membranes and bind to internal regulators

1.) polypeptides (proteins and peptides)

2.) amines derived from amino acids

3.) steroids (cholesterols)

1.) different receptors for the hormone

2.) different signal transduction pathways

3.) different proteins for carrying out the reponse

- a hormone can also have different effects in different species

-paracrine signaling: non hormonal chemical signals (local reg.) elicit responses in nearby target cells

examples:

1.) cytokines and growth factors (proteins). immune function.

2.) nitric oxide (gas). vasodilation of peripheral blood vessels.

3.) prostaglandins (fatty acids): regulate aggregation of platelets, and early step in formation of blood clots.

-in response to internal/external stimulus, hormones are released from endocrine cells, travle thru bloodstream, and interact with target cells to cause a physiological response

- response leads to a reduction in the stimulus and the pathway stops

-insulin: reduces blood glucose levels by...

1.) promoting cellular uptake of glucose

2.) slowing glycogen breakdown to lucose in liver

3.) promoting fat storage

-glucagon: increase blood glucose levels by...

1.) stimulating breakdown of glycogen to glucose in liver

2.) stimulating breakdown if fat and protein into glucose

diabetes mellitus

-diabetes mellitus: caused by a deficiency of insulin or a decreased response to insulin in target tissues

1.) type 1 (insulin dep.): insulin deficiency due to autoimmune disorder in which the immune system destroys pancreatic cells

2.) type 2 (non-insulin dep): insulin deficiency or more commonly a reduced response of target cells due to change in insulin receptors

-signals from nervous sys initiate and regulate endo. signals

-hypothalamus: recieves info. from nervous system and initiates responses through the endocrine system

-pituitary gland: attached to the hypothalamus and stores and secretes hormones

-hormone cascade pathways: hormone stimulates the release of a series of other hormones, the last of which activates a target cell

- hormone cascade pathways are usually regulated by negative feedback

1.) thyroid hormones: T3 and T4 hormones control of metabolism and development

2.) adrenal hormones: response to stress (fight or flight) with epinephrine (adrenaline), norepinephrine (noradrenaline), corticosteroids

3.) gonadal sex hormones: gonads (testes and ovaries) produce androgens (testosterone), estrogens (estradiol), progestins (progesterone)

-neuron: cell that signal info within the body

-neurons use 2 types of signals to communicate

1.) electrical signals: long distnace communication

2.) chemical signals: short distance communication

1.) sensory neuron: carry signals into the nervous system

2.) interneurons: process signals in the nervous system

3.) motor neurons: carry signals out of the nervous system to muscles and glands

nervous system processes information in 3 stages:

1.) sensory input: sensors detect external and internal conditions and transmit sinals along sensory neurons

2.) integration: sensory signals are sent to interneurons for integration/processing

3.) motor output: motor output signals leave interneurons along motor neurons, which trigger muscles or glands

1.) cell body: most organelles and nucleus

2.) dendrites: numerous, highly branched extensions of cell body that recieve signals from other neurons

3.) axon: single, long extension that transmits signals to other cells

4.) axon hillock: where exons join cell body

5.) synapse: junction b/w 2 neurons

6.) synaptic terminal: end of 1 axon that passes info. across a synapse in the form of neurotransmitters (chem. signal)

-glia: cells that nourish, support, and insulate the nervous system

-glia cells that insulate neurons: form myelin sheaths around axons of many vertebrate neurons:

1.) oligodendrocytes: insulate the CNS neurons

2.) Schwann cells: insulate the PNS neurons

-myelin sheath: plasma membranes are mostly lipid, which is a poor conductor of electrial currents

-resting potential: membrane potential of a neuron that is not transmitting signals. it depends on ionic gradients across the plasma membrane.

- the membrane resting potential can change from its resting potential when the membranes permeability to particular ions changes

- neurons contain gated ion channels that open or close in response to stimuli to generate the signals of the nervous system

1.) ligand-gated ion channels: found in dendrites and open.close when a specific chemical binds to the channel

2.) stretch-gated ion channels: found in dendrites and open when the membrane is mechanically deformed

3.) voltage-gated ion channels: found in the axons and open/close when the membrane potential changes

-graded potential: change in membrane potential where the magnitude of the change varies with the strength of the stimulus: larger stim. causes a larger change in the mem pot.

1.) hyperpolarization: inside of the cell becomes more negative (K+ diffuses out)

2.) depolarization: inside of the cell becomes less negative (Na+ diffuses in)

- a stimulus strong enough to produce depolarizations that reach the threshold (volatge at which graded pot. become 1 act pot) volatge will trigger an action potential

-action potentials: breif all-or-none depolarization of a neurons plasma membrane that carries info along the entire axon length

action potential=neuron fires

-information is conveyed as:

1.) presence of signal in a neuron

2.) number of signals in a neuron

- there are no weak or strong signals, they're all the same intensity

-an AP travels long distances by depolarizing to threshold neighboring regions of the axon

-speed of AP increases with:

1.) axon diameter: larger diameter neurons have more ion gates

2.) axon insulation: in vertebrates, myelination causes saltatory conduction, APs jump along the axon's length

1.)electrical synapse: current flows directly from 1 cell to another via a gap junction

2.) chemical synapse (most common): release of a chemical neurotransmitter stored in presynaptic neurons

1.) diffuses out of the synaptic cleft

2.) taken up by surrounding cells

3.) degraded by enzymes in the synaptic cleft

-unlike AP, PSP are graded and do not regenerate

-summation can depolarize a neuron and cause an AP:

1.) temporal summantion: 2 EPSPs are produced in rapid succession at a single synapse

2.) spatial summation: EPSPs produced simultaneously by diff synapses on the same postsynaptic neuron add together

-a neurotransmitter binds to a receptor that is not part of an ion channel

-this binding activates a signal transduction pathway involving a second messenger in the postsynaptic cell

-effect on indirect synaptic transmission have a slower onset but lasts longer

1.)acetylcholine:common and can be inhib. or excit. depending on the type of receptor

2.)biogenic amines:active in the CNS and PNS

3.)4 amino acids: neurotransmitters in the CNS and several neuropeptides also function as neruotransmitters

4.)gases: local regulators in the PNS

1.) CNS: ganglia arranged in a brain and nerve chord

2.) PNS: sensory and motor neurons that connect the CNS with the rest of the body

-in vertebrates the CNS runs along the dorsal side of the body and the PNS(nerves and ganglia) branch out laterally

1.)white matter: axons in the cns whose myelin sheaths give them a whitish appearance

2.)gray matter: dendrites, unmyrlinated axons and neuron cell bodies

-motor neurons carry signals away from cns

a.)somatic nervous system(voluntary): carries signals to skeletal muscles

b.)autonomic nervous system(involuntary): regulates internal environment

i.)sympathetic division: fight or flight

ii.) parasympathetic: rest and digest

iii.)enteric division:digestive tract,pancreas, and gallbladder

-homeostasis,coordination of movement, and conduction of info. to higher brain centers

1.)medulla oblongata:breathing,heart and blood vessel activity, swallowing, vomiting, digestion

2.)pons: breathing

3.)midbrain:recieves and integrates sensory info.

1.)epithalamus:pineal gland and choroid plexus

2.)thalamus: main input and output center for sensory info to and from the cerebrum

3.)hypothalamus:regulates homeostasis and basic survial behaviors(feeding,fighting,fleeing,reproducing, and sleeping)

-divided into left and right hemispheres

-each has:

a.)cerebral cortex:largest and most complex part of the brain

i.)neocortex:convoluted surface of 6 parallel neuron layers (grey matter)

ii.)basal nuclei: planning and learning movement sequences (white matter)

-corpus callosum: fibers that exchange info b/w the 2 hemispheres

-sensory info is analyzed, motor commands are issued and language is generated

1.)occipital lobe: visual info

2.)temporal lobe: auditory input

3.)parietal lobe: somatosensory input (tastes, touch, pain, pressure, temp.)

4.)frontal lobe: olfactory input

-association area most impor. in humans

1.) left hemisphere: language, math, logic, and processing of serial sequences

2.) right hemisphere: pattern recognition, nonverbal thinking, patterns of speech, and emotional processing

-corpus callosum: fibers that exchange info b/w the 2 hempisheres