Chapter 11: Control: The Nervous and Endocrine Systems Flashcards
nervous system
-detects and interprets info from the surrounding environment
endocrine system
-controls body functions through the use of chemical messengers called hormones
nerve cells
- AKA neurons
- highly specialized cells that carry impulses between body parts
- consists of cell body, dendrites, axon terminal, nucleus, myelin sheath
resting state of neuron
-polarized (inside of neuron is negatively charged)
resting membrane potential
- around -70 mV
- RMP is set up and maintained by 2 membrane proteins (Na+/K+ ATPase and the K+ leak channel)
sodium-potassium pump (Na+/K+ ATPase)
-protein channel that uses one molecule of ATP to pump 3 Na+ out of the cell and 2 K+ into the cell
leak channels
-potassium channels that are always open and will always allow K+ to leak out of the cell according to its gradient, allowing for a negative charge in the membrane
action potential
- once the threshold (-50mV) is reached with a small influx of sodium, voltage-gated sodium and potassium channels open
- sodium enters the cell with concentration gradient, depolarizing the cell further (until 35 mV) before the sodium channels shut
- voltage-gated potassium channels open, allowing potassium to exit with the concentration gradient, repolarizing the cell and reaching -90mV before closing
- membrane proteins return to the RMP
Schwann cells
-make up the myelin sheath (speeds rate at which action potential can travel down the axon)
nodes of Ranvier
-spaces between the Schwann cells that can fire an action potential
saltatory conduction
-the jumping of the axon potential from node to node that increases the traveling of the signal
refractory period
- membrane is unable to fire a second action potential until resting potential is set
- ensures that signal travels down one direction
synapse
-neuron-to-neuron or neuron-to-organ junction that releases neutrosmitter (chemical such as Acetylcholine that can lead to alzheimers disease) to pass the impulse
synaptic cleft
- small gap between neurons
- neurotransmitters are released into synapse by exocytosis where they diffuse across the synaptic cleft and bind to the receptors on the dendrites
- then usually causes the opening of sodium ion channels so sodium flows into the cells, allowing for the threshold to be reached
effects of neurotransmitters
-some cause the cell to be stimulated (reach threshold), inhibited (away from threshold)
summation
-sum of stimulatory and inhibitory input
CNS
-brain and spinal cord that process and integrate info, and then sends decisions to body through PNS
interneurons
-part of the CNS that connect sensory and motor neurons
sensory neurons
-sends info to the CNS from sensory organs
motor neurons
-neurons involved in sending info from the CNS to the organs of the body
frequency of action potential
-determines how often the threshold is reached, and therefore how strong the stimulus is
spinal cord
-primitive, reflex actions
cerebrum
-conscious mind (movement, speech, problem solving, senses)
cerebellum
-coordinates movement and balance
medulla
-involuntary actions (breathing, blood pressure regulation)
hypothalamus
- maintains homeostasis
- monitors hormone levels, temperature, etc.
- controls pituitary gland
somatic
- voluntary movement of skeletal muscles
- when acetylcholine binds to receptors on the muscle, this causes the muscle to depolarize and contract
autonomic
- involuntary system
- sympathetic: fight-or-flight (increases blood pressure, heartrate, breath rate, blood flows toward skeletal muscles)–> involed with noepinephrine
- parasympathetic: rest-and-digest (mostly uses acetylcholine)
ganglia
- clusters of nerve cell bodies along the nerve cord
- neurons branch from
- present in arthropods (insects) and annelids (worms)
endocrine glands
-secrete hormones that can only affect organs with a receptor for that hormone
peptide hormones
- amino acid-based
- bind to receptors outside the cell, quickly turning existing enzymes in the cell on or off
- insulin, prolactin, glucagon
steroid hormones
- cholesterol-based
- bind to receptors inside the cell (intracellular)
- bind to DNA and change which genes get transcribed
- estrogen, testosterone
pituitary gland
- master regulatory gland because its hormones control other endocrine glands
- controlled by the hypothalamus
- has 2 lobes
anterior pituitary gland
- growth hormone (GH)
- thyroid stimulating hormone (TSH)
- adrenocorticotropic hormone (ACTH)
- follicile stimulating hormone (FSH)
- luteinizing hormone (LH)
- prolactin
- for every hormone released by APG, there is a corresponding releasing hormone from the hypothalamus
growth hormone (GH)
- target: all tissues and organs
- important in children
- in adults, stimulates the cell-turnover rate
thyroid stimulating hormone (TSH)
-stimulates the thyroid gland to secrete thyroid hormones
adrenocorticotropic hormone (ACTH)
-stimulates adrenal cortex (outer layer of the adrenal gland) to secrete its hormones
follicile stimulating hormone (FSH)
- target: gonads
- causes ova to mature and release estrogen
- cases sperm to be produced
luteinizing hormone (LH)
- target: gonad
- stimulates ovaries, causes development of a corpus luteum
- stimulates testes to produce testoterone
prolactin
- released after childbirth
- stimulates mammary glands to produce breast milk
posterior pituitary gland
- oxytocin: causes uterus to contract during childbirth, causes the mammary glands to release breast milk during feeding
- antidiuretic hormone (ADH): causes kidneys to retain water (AKA vasopressin)
- oxytocin and ADH are made in hypothalamus and released by an action potential
thyroid gland
- secretes 2 hormones
- thyroxine (thyroid hormone): affects most of the body’s cells by increasing the rate of metabolism
- calcitonin: activates special cells in bone that remove calcium from the blood and use it to build new bone (reduce blood calcium levels)
hypothyroidism
- lower than normal levels of thryroxine
- don’t have enough iodine, then not enough thyroxine bc thyroxine contains iron
- causes low metabolic rate
hyperthyroidism
- overproduction of thyroxine
- produces higher than normal metabolic rate accompanied with weight loss and fast heart rate
parathyroid glands
- 4 glands that are found on the back of the thyroid gland
- secretes parathyroid hormone/parathormone (activates special cells inthe bone that dissolve the bone to release calcium into the blood)
calcium
-functions in nerve impulse conduction, heart contraction, and blood clotting
adrenal glands
- located on kidneys
- adrenal medulla and adrenal cortex
adrenal medulla
- secretes epinephrine (adreneline) and norepinephrine (noradrenaline)
- both hormones can bind to the same receptors and have the same effects on organs
- epinephrine and norepinephrine from the adrenal medulla increase and prolong the effects of the Sympathetic NS
adrenal cortex
-secretes 3 types of steroids: glucocorticoids, mineralocorticoids, and sex steroids
glucocorticoids
- target: liver
- cause production of glucose from fats and proteins to release new glucose into the blood (known as gluconeogenesis)
- target: body cells
- cause use of fats for fuel instead of glucose, causing an increase in blood glucose levels and increased body metabolism
- strong anti-inflammatory agents
- primary ex: cortisol
mineralocortocoids
- target: kidney
- primary ex: aldosterone (causes the retention of sodium in the kidneys)
- the removal of sodium from the urine causes the removal of H2O, and therefore increases blood volume and pressure
sex steroids
-produced by adrenal cortex, but mainly from the gonads
pancreas
- secretes hormones and digestive enzymes
- secretes insulin and glucagon
Islets of Langerhans
- cells in pancreas that produce insulin and glucagon
- AKA islet cells
insulin
- secreted when glucose levels are high
- affects all cells in the body, allowing for cells to take in glucose so they can use it in cellular repsiration
- stimulates the liver to store glucose as glycogen
- blood glucose levels decrease
glucagon
- released when blood glucose levels are low
- targets liver
- causes liver to break down glycogen (stored glucose) and release free glucose into the blood (called glycogenolysis)
- blood glucose levels increase
gonads
- produce gametes and secrete hormones (sex steroids)
- testes and ovaries
- male sex steroid: androgen (primary type is testosterone)
- female sex steroid: estrogens (most common is estradiol) and progesterone
- estrogen: stimulates growth of uterin lining in menstrual cycle, progesterone maintains the lining in the second half
