Exam 3 Flashcards
How are hormones transported throughout the body?
Hormones rely on capillary network (no ducts) to move throughout the body (moves in blood stream through whole body but only targets cells that have specific receptors
Thyroid gland
largest endocrine gland, made mostly of thyroid follicles (protein and thyroglobulin rich sacs) secretes T3 & T4 in RESPONSE to TSH
What are the functions of the thyroid gland?
in endotherms increases molecular activity of the mitochondria which leads to an increase of metabolic rate, O2 consumption, heat production (calorigenic effect), appetite, growth hormone secretion, alertness, and reflex speed
In ectotherms thyroid hormone affects body temperature, growth, molting, and gonad maturation
what hormones are secreted by the thyroid gland?
Thyroid hormone: T3 (triiodothyronine) and T4 (thyroxine)
Ultimobranchial bodies location
mammals: part of thyroid, form population of parafollicular (C) cells
fish, amphibians, reptiles and birds: separated paired cell masses in the throat
Ultimobranchial bodies hormones secreted
CALCITONIN, lowers blood levels of calcium by extracting calcium from blood and depositing it in bones
Ultimobranchial bodies function
stimulate osteoblast activity and bone formation in children
Parathyroid glands location/anatomy
mammals: 4 glands in posterior of thyroid gland
other vert.: located on thyroid and dispersed along veins in neck
Parathyroid hormones
secretes parathyroid hormone (PTH), works with calcitonin, kidney keeps calcium and pulls calcium from secretion
Parathyroid hormones function
increases blood Ca2+ levels by promoting kidney retention
*teleosts instead regulate calcium using stomolactin from pituitary and store it in their scales
Thymus location/anatomy
bilobed gland in the mediastinum superior to heart, Goes through involution (shrinking) at puberty
Thymus hormones
secretes hormones (thymopoietin, thymosin, and thymulin) that stimulates development of other lymphatic organs and activity of T lymophocytes
*Site of mature T cells for immune defense
Thymus function
main function is developing immune systems in babies and kids
thymus influences 3 systems: endocrine, lymphatic, and immune
Adrenal glands mammals anatomy
fusion of 2 glands: Medulla (inner core) and cortex (outer core)
Medulla: smaller inner core of adrenal gland, high blood flow, from neural crest
Cortex: larger outer layer, high lipid and cholesterol concentration, from splanchnic mesoderm
chromaffin cells
modified sympathetic neurons without dendrites or axons
Adrenal glands anatomy in fish, amphibians, and amniotes
Fish: medulla and cortex are separate in pronephros/kidney area
Amphibians: tissues intermingle and form strands near kidneys
Amniotes: cortical cell and chromaffin cells mingle near kidney but not integrated, receive their own blood supply
Adrenal gland hormones secreted
CATACHOLAMINES (epinephrine and norepinephrine) and dopamine (from chromaffin cells in medulla)
CORTICOSTEROIDS: stress hormones and sex hormones, released from the cortex (in non-mammals cortical hormones are used to regulate sodium transport and metabolism)
Adrenal gland function
Fight or flight hormones (increase allertness and blood to heart and lungs, decrease digestion and urine production)
Stress and sex hormones
Pancreatic islets anatomy
tetrapods: composite gland with endocrine and exocrine chunks
cyclostomes and telosts: pancreatic islet tissue found along the liver, gallbladder, and bile ducts (exocrine and endocrine separate but close)
chondrichthyans and coelacanths: islets near ducts and within the pancreas
Pancreatic islets hormones
Alpha cells: secrete glucagon between meals when blood glucose concentration is falling
Beta cells: secrete insulin during and after meal when glucose and amino acid blood levels are rising
Delta cells: secrete somatostatin, which inhibits both glucagon and insulin
Pancreatic islets function
Secretes hormones to regulate blood glucose levels
Glucagon: prevents drop of blood glucose
Insulin: lower blood glucose (glucose into cells)
Somatostatin: inhibits glucagon and insulin
Hypothalamus location/anatomy
Shaped like a flattened funnel and forms floor and walls of third ventricle of brain
hypothalamus relation with pituitary gland
pituitary gland is suspended from hypothalamus by a stalk (infundibulum), pituitary gland carries out most of the functions of the hypothalamus
pituitary gland anatomy
kidney bean attached to hypothalamus by infundibulum
composed of 2 structures of independent origins
anterior pituitary (adenohypophysis)
Posterior pituitary (neurohypophysis)
hypothalamus function
master regulator of endocrine system
Regulates primitive functions from water balance and thermoregulation to sex drive and childbirth
(*sends directions to pituitary gland who then sends hormones to regulate the rest of the body)
Anterior pituitary gland location
linked to hypothalamus by hypophysial portal system (2 capillary beds before heart, hypothalmic releasing and inhibiting hormones regulate anterior pituitary secretions
Follicle stimulating hormone (FSH)
Anterior pituitary gland, secretion of ovarian sex hormones, development of ovarian follicles, and sperm production
Luteinizing hormone (LH)
anterior pituitary gland, stimulates ovulation, progesterone secretion, testosterone secretion
Thyroid-stimulating hormone (TSH)
anterior pituitary gland, secretion of thyroid hormone & growth of thyroid gland
Adrenocorticotropic hormone (ACTH)
anterior pituitary gland, stimulates adrenal cortex to secrete glucocorticoids (especially cortisol), important in stress response
Prolactin (PRL)
anterior pituitary gland, -stimulates mammary glands to make milk
Growth hormone (GH)
anterior pituitary gland, stimulates mitosis and cellular division
- Six different hormones are secreted by the anterior pituitary gland. Name three of these and describe their target organs and their functions.
o Prolactin (PRL): stimulates mammary glands to make milk
o Luteinizing hormone (LH): targets reproductive system, stimulates ovulation, progesterone secretion, testosterone secretion
o Thyroid stimulating hormone (TSH): secretion of thyroid hormone and growth of thyroid gland
posterior pituitary location/anatomy
much smaller than anterior pituitary, nerve tissue not a true gland, nerve cell bodies in hypothalamus pass down the stalk as hypothalamo-hypophysial tract, hypothalamic neurons secrete hormones that are stored in neurohypophysis (AKA posterior pituitary) until released into blood
Posterior pituitary hormones
Antidiuretic hormone (ADH) - increases water retention, thus reducing urine volume and preventing dehydration concentrates urine by pulling water into kidney tubules
Oxytocin (OT) - promotes feelings of emotional bonding between partners, Stimulates labor contractions during childbirth, Stimulates flow of milk during lactation, love sex and birth
pineal gland (epiphysis) location/anatomy
in brain, attached to roof of 3rd ventricle beneath posterior end of corpus callosum
*in many vertebrates it is located just under the skin on the top of the head (containing photoreceptors)
pineal gland hormones
melatonin, may also regulate other hormones and the immune systemp
pineal gland function
influences timing of puberty in humans (undergoes involution at 7)
plays role in circadian rhythms (synapses with optic nerve fibers)
may help regulate other hormones and the immune system
informs about seasonal rhythms for mating
Gastrointestinal tract hormones in amniotes vs fishes
amniotes: gastrin, secretin, cholecystokinin (CCK)
fishes: bombesis
gastrin
secreted by stomach, which stimulates secretion of enzymes and hydrochloric acid
secretin
when chyme moves to the intestines, stimulates bicarbonate release to buffer low pH (so pancreatic enzymes can be effective)
cholecystokinin (CCK)
activated by intestine, secreted by CCK cells Stimulate pancreas to secrete juice Stimulate gallbladder to release bile
bombesin
replaces gastrin and is secreted by stomach to release gastric acid
Bombesin has a wide range of effects apart from the stomach (thermoregulation, digestive motility) so replacement by gastrin allows hormones to become more specialized
ovaries homones
theca cells make androstenedione converted to estradiol by granulosa cells (most common form of estrogen) after ovulation the remains of the follicle become the corpus luteum and secrete progesterone
functions of estradiol and progesterone
Development of female reproductive system and physique including adolescent bone growth
Regulate menstrual cycle, sustain pregnancy
Prepare mammary glands for lactation
Intersitial cells
cells nestled between seminiferous tubules, release testosterone and other steroids
testosterone
Stimulates development of male reproductive system in fetus and adolescent, and sex drive
Sustains sperm production
Evolutionary trends in the endocrine system across vertebrates
Endocrine organs often more dispersed/less compacted in fishes and amphibians than in amniotes:
Adrenal glands – adrenocortical tissue and chromaffin
cells go on to form cortex and medulla in amniotes
Incorporation of parafollicular cells into thyroid gland
Pancreatic islet cells within pancreas
Functions of hormones differ across vertebrate groups:
Prolactin stimulates milk production in mammals
but promotes growth and pigment development in
reptiles and amphibians
New hormones replace function of old ones in some systems:
Example: gastrin replaces bombesin and CCK in
stomach in birds and mammals; CCK moves to
intestine
CNS components and terminology
central nervous system containing brain and spinal cord
a collection of nerve fibers traveling together is a tract in CNS
a collection of nerve cell bodies is a nucleus in CNS
PNS components and terminology (PNS)
PNS is broken into sensory division (containing visceral sensory division and somatic sensory division) and motor division (containing somatic motor division and Visceral motor division (made of sympathetic and parasympathetic divisions) )
a collection of nerve fibers traveling together is a nerve in PNS
a collection of nerve cell bodies is a ganglion in PNS
visceral sensory
*return signals from body organs, blood vessels, airways
division of PNS, monitor the internal environment and organ systems.
visceral motor
*sends signals to visceral muscles in gut, heart, exocrine glands, ect.
division of PNS, controls involuntary functions mediated by the activity of smooth muscle fibers, cardiac muscle fibers, and glands.
somatic sensory
*returns signals from external stimuli (olfactory, mechanical, thermal)
division of PNS, conscious perception of touch, pressure, pain, temperature, position, movement, and vibration
has two major components: a subsystem for the detection of mechanical stimuli (e.g., light touch, vibration, pressure, and cutaneous tension), and a subsystem for the detection of painful stimuli and temperature.
somatic motor
*sends signals out to govern locomotor response
division of PNS, allows you to move and control muscles throughout your body. It also feeds information from four of your senses — smell, sound, taste and touch — into your brain
Receptors vs effectors
The nervous system RECIEVES information from one or more receptors
the nervous system TRANSMITS information to one or more effectors, can be mechanical (muscles) or chemical (glands)
Neuroglia (nerve +glue)
microglia, oligodendrocytes, schwann cells, ependymal cells, astrocytes, satellite cells
*glial cells do not transmit impulses and instead support , nourish, insulate neurons and bind together nervous tissue
microglia
macrophages that clean debris, CNS
oligodendrocytes
cells insulate axons, CNS
schwann cells
insulate axons, PNS
astrocytes
pass nutrients between blood capillaries and neurons, guide neuron development and regulate chemical communication, CNS
ependymal cells
line the central canal of the brain and spinal cord (CNS)
satellite cells
surround sensory ganglia, PNS
dendrites
receive incoming electrical signals, centrally located around a large nucleus
axon
part of neuronal process, specialized for long-distance transmission of stimuli, one long axon per neuron, carry impulses AWAY
Myelinated nerves
wrapped in myelin sheath (made of schwann or oligodendrocytes), allows for faster conduction, neuroglial cells produce myelin sheath
mylin
plasma membrane of glial cells, mostly lipid, segmented made of oligodendrocytes in CNS and schwann cells in PNS, neurilemma is thick outermost coil of myelin sheath that contains schwann cells nucleus
how is the presence of myelin sheaths distributed across vertebrates?
lampreys and hagfish lack myelinated neurons but all other vertebrates have them, may have evolved in jawed vertebrates or in ostracoderms
multipolar
neuron type, one axon and multiple dendrites, most common neuron type in CNS (receives a lot, few out)
bipolar
neuron type, one axon and one dendrite, sensory, common in olfactory cells, retina, inner ear
unipolar
neuron type, single process leading away from cell body, sensory cells from skin and organs to spinal cord
anaxonic
neuron type, many dendrites but no axon, retina brain adrenal gland (chromaffin cells) all incoming no out going
Sensory (afferent) neurons
functional class of neurons, PNS, detect stimuli and transmit information to the CNS
interneurons
functional class of neurons, many, confined to the CNS and connect motor and sensory pathways, receive signals from many neurons and carry out integrative functions (make decisions on responses)
motor (efferent) neurons
functional class of neurons, PNS, send signals out to the muscles and glands (the effectors)
Sensory vs motor neurons
sensory neurons take info from PNS and send it to CNS
motor neurons take info from CNS and send it to PNS
Nerve cell regeneration
some regeneration can occur in PNS if some intact and some neurilemma remains process is very slow and come axons connect with wrong fibers
Axon distal to injury degenerates
Cell body swells; nucleus moves off center due to loss of growth factors from target cell
Axon stump sprouts multiple growth processes
Schwann cells, basal lamina, neurilemma form regeneration tube
Regeneration tube guides new growth
Contact is reestablished with target, cell body shrinks back down
Atrophied muscle fibers regrow
Resting membrane potential
difference in charge across the plasma membrane when no signals are being sent
extracellular fluid has more Na+, intercellular fluid has more K+, this causes diffusion and selective permeability, creates an electrical attraction of anions and cations
Local potential
change in membrane potential at and nearby point of stimulation
begins at dendrites and spreads to some axons, causes depolarization if enough cells respond
Depolarization of local potentials
sodium coming in cancels some of negative charge and membrane voltage drifts closer to zero
Action potential
rapid up and down shift in membrane potential that can travel a long distance, triggered by excitatory local potentials when they reach an area with high enough density of voltage gated channels
depolarization of action potentials
voltage gated ion channels open and an action potential is produced
repolariation
potassium ions exit the cell and repolarize the membrane (return to resting membrane potential)
Hyperpolarization
potassium ions slightly overshoot and hyperpolarize before membrane returns to resting potential
Synapses
gaps between neuron junctions
1st neuron is presynaptic (releases neurotransmitter)
2nd neuron is postsynaptic (responds to neurotransmitter)
neurotransmitter
chemical signals that are generated at synapses
ex) acetylcholine, norepinephrine, serotonin, dopamine
meninges
protective physical barrier around brain and spinal cord, protects from pathogens, made of three fibrous membranes (dura mater, arachnoid mater, and pia mater)
cauda equina
lumbar region thickens and branches into cauda equina (spinal nerves) in mammals
dura mater
outer layer of meninges, forms loose dural sheath (tough and thick)
arachnoid mater
middle layer of meninges, five or six layers of looser cells with collagen and elastic fibers, adheres to dura
subarachnoid space
between arachnoid mater and pia mater, filled with cerebrospinal fluid (CSF)
pia matter
innermost layer of meninges, delicate and transparent, 1-2 layers of cells with collagen and elastic fibers, follows contours of spinal cord
Gray matter
center of spinal cord had posterior dorsal horns that receive sensory information and anterior ventral horns that send out motor information, connected by gray commissure and the thoracic region have a lateral horn that contains neurons of the sympathetic nervous system
Spinal cord white matter
outer layer of spinal cord, surrounds the gray matter and consists of bundles of axons that course up and down the cord providing communication between different levels of the CNS (long neuron columns/tracts)
ascending tracts
part of white matter of spinal cord, carry sensory information up the spinal cord to the brain
descending tracts
really long neurons, conduct motor impulses down the spinal cord away from the brain
Which spinal nerves transmit which kind of information (sensory/motor)
Sensory information: ascending tracts (white matter), posterior (dorsal) horns (grey matter)
Motor information: Descending tracts (white matter), anterior (ventral) horns (grey matter)
Which vertebrates have different spinal cords from the rest
lampreys: spinal cord is thin and avascular, no distinction between white and grey matter (because no myelin)
Gnathostomes: spinal cord has grey matter but many nerve synapses extend into white matter (grey and white matter connected)
Amniotes: nerve synapses are all contained within grey matter, white matter contains only nerve tracts (more tracts means more control over body movements)
Endoneurium
covers each never fiber (axon)
perineurium
covers a bundle of fibers (fasicle)
epineurium
covers each collection of fascicles=nerves
nerve organization
endoneurium-> perineurium (fascicle) -> epineurium (nerve)
Afferent fibers
part of spinal nerves, enter via dorsal/posterior roots and bring in sensory information
efferent fibers
part of spinal nerves, enter via ventral/anterior roots and send out motor information
Dorsal root ganglia
collections of nerve bodies whose axons contribute to spinal nerves
Sympathetic chain ganglia
paired series of ganglia adjacent to vertebral column or notochord, connect spinal nerves along body axis
nerve plexus
complex networks of nerves that are distributed to muscle groups
cervical plexus
in the neck, C1 to C5: supplies neck and phrenic nerve to the diaphragm
brachial plexus
near the shoulder, C5 to T1: supplies upper limb and some of shoulder and neck
lumbar plexus
in the lower back, L1 to L4: supplies abdominal wall, anterior thigh, and genitalia
sacral plexus
in the pelvis, L4, L5, and S1 to S4: supplies remainder of lower trunk and lower limb
How does the spinal cord differ across vertebrates?
Lampreys: spinal nerves do not merge
Fish & amphibians: dorsal and ventral nerves on spinal cord merge, visceral motor exit dorsal and ventral
Amniotes: dorsal and ventral nerves on spinal cord merge, visceral motor exits through ventral
reflex arc
sensory neurons to interneuron to motor neurons (don’t travel to brain, just to spinal cord and back)
What does the autonomic nervous system do, and what are the two main components
Autonomic: peripheral nerves and ganglia control visceral activity (involuntary); include both sensory and motor components *breath, heart, blood, and digestion
two main components: sympathetic (fight or flight) and parasympathetic (rest and digest)
sympathetic nervous system
part of autonomic nervous system
prepares body for action (fight or flight)
Slows digestion, increases heart rate and BP, mobilizes glucose
thoracolumbar outflow
Parasympathetic nervous system
part of autonomic nervous system
restores body to restful state (rest and digest)
Stimulates digestion, slows heart rate, drops BP, stores glucose
craniosacral outflow
Thoracolumbar outflow
visceral motor neurons depart from thoracic and lumbar regions
craniosacral outflow
cranial nerves VII, IX, X along with some visceral motor neurons depart from sacral region
Enteric autonomic system
sensory and motor neurons in the walls of the digestive tract (many neurons here; well known in mammals)
*Digestive regulation nerves
myenteric plexus sits in outer wall of smooth muscle
submucosal plexus is located deep within smooth muscle
Longitudinal fissure
deep groove that separates hemispheres (center line)
gyri
thick folds on brain surface in some mammals (packs more neurons in) folds (increase SA and volume)
sulci
shallow grooves between gyri, grooves (increase SA and volume)
corpus callosum
thick nerve bundle at base of longitudinal fissure that connects hemispheres (white matter tracts between hemispheres)
two lateral ventricles
fluid filled chamber within brain, one in each cerebral hemisphere (double)