nervous system functions
-directs immediate responses to stimuli
-coordinates or moderates activities of other organ systems
-provides and interprets sensory information about external conditions
nervous tissue
neurons and neuroglia
message that are sent across the plasma membranes of neurons are called
action potential
Define action potential
a change in charge across the membrane of a neuron
what causes a change in charge across the membrane of a neuron?
sodium rushing in
Central Nervous System (CNS) consists of
the brain and spinal cord
Peripheral Nervous System (PNS) consists of
cranial nerves and spinal nerves
two parts of the peripheral nervous system
efferent/motor
afferent/sensory
two parts of the motor/efferent division of the peripheral nervous system
somatic & autonomic
two parts of the autonomic nervous system
sympathetic and parasympathetic
what propagates an action potential
when a neuron is stimulated past a certain threshold
define chemical synapse
a type of synapse in which messages are transmitted from one neuron to another by chemical neurotransmitters
synapse
the junction between the axon tip of the sending neuron and the dendrite or cell body of the receiving neuron
three main types of neurons
sensory neurons
motor neurons
interneurons
sensory neurons transmit signals from > to
from sensory receptors to the central nervous system
sensory receptors
Specialized cells unique to each sense organ that respond to a particular form of sensory stimulation.
(touch, pain, temperature, hearing, sight, smell, and taste)
motor neurons transmit signals from > to
from the central nervous system to the rest of the body (ex. skeletal muscle, glands)
internuerons transmit signals
between neurons
three basic parts of a neuron
soma (cell body)
axon
dendrites
dendrites function
receives impulses
axon function
send signal from the neuron to the next cell
Axons are insulated by
myelin sheath
Oligodendrocytes
Type of glial cell in the CNS that form the myelin sheath
(can for myelin sheath for many axons)
myelin sheath
covers the axon of some neurons and helps speed neural impulses
nodes of ranvier
gaps of unsheathed axon between schwann cells
Schwann cells
type of glial cell in the PNS that wraps around the axon to form a myelin sheath
(can form myelin sheath for only one axon)
the spinal cord is encase in
vertebrae
vertebrae function
protect/support spinal cord
three parts of the brain
hindbrain, midbrain, forebrain
Hindbrain includes
medulla, pons, cerebellum
midbrain (mesencephalon)
integrates sensory signals and orchestrates responses to these signals
vision and hearing
forebrain includes
cerebrum, thalamus, hypothalamus.
cerebral cortex (cerebrum)
-grey, wrinkled surface that is densely packed with neurons
-located in upper forebrain
-connections between neurons grow as we learn and develop
-surface is wrinkled to increase surface area (convolutions)
-higher thinking
the brain is divided into ___ hemispheres
2
the brain is divided into ___ lobes
4
Four lobes of the brain
frontal, parietal, occipital, temporal
frontal lobe functions
-short term memory
-working memory
-information processing
-decision making
-planning
-judgement
parietal lobe functions
-sensory input
-spacial positioning of the body
occipital lobe functions
-visual input
-visual processing
-visual output
(nerves from the eyes enter directly into this lobe)
temporal lobe functions
-auditory input
-auditory processing
-auditory output
Cerebellum
the "little brain" at the rear of the brainstem;
functions
balance and coordination
storing implicit memories (ie learned techniques)
processing sensory input
brain stem consists of (3 parts)
midbrain, pons, medulla oblongata
brain stem functions
breathing, heart rate, blood pressure
information passes through the brain stem
Pons location
between midbrain and medulla oblongata
information is sent across the pons from > to
cerebrum to medulla and cerebellum
medulla oblongata
Part of the brainstem that controls vital life-sustaining functions such as heartbeat, breathing, blood pressure, and digestion.
connects the brain to the spinal cord
Somatic Nervous System (SNS)
the part of the peripheral nervous system that controls voluntary movement of skeletal muscles
autonomic nervous system
the part of the peripheral nervous system that controls the glands and the muscles of the internal organs (such as the heart). Its sympathetic division arouses; its parasympathetic division calms.
efferent nerves
motor nerves
afferent nerves
sensory nerves
three types of muscle
skeletal, cardiac, smooth
what three properties do all muscle tissue types have in common
1) excitability
2) contraction (shorten)
3) elongation (relaxation)
skeletal muscle characteristics
voluntary, striated, multinucleated
smooth muscle characteristics
Not striated
Spindle-shaped
single, central nucleus
More actin than myosin
involuntary
cardiac muscle characteristics
branched
striated
involuntary
a muscle contains many
muscle fasicles wrapped in perimysium
a muscle fasicle contains
muscle fibers separated by endomysium
a muscle fiber contains
a bundles of myofibrils
Myofibrils contain
microfilaments
(myosin and actin)
striations are formed by
myosin and actin protein filaments
when an action potential reaches a muscle fiber ______________ _________ are released
calcium ions
myosin heads bind to
actin
atp provides
energy for muscle contraction
(and all cell activities)
Functions of the male reproductive system
produce, maintain, and transfer sperm and semen
produce and secrete male hormones
external structures of the male reproductive system
penis, scrotum, testes
the penis contains
the urethra
erectile tissue
the scrotum is
a sac of skin and smooth muscle that houses the testes
the testes produce
sperm and testosterone
internal structures of the male reproductive system
epididymis
vas deferens
ejaculatory ducts
urethra
seminal vesicles
prostate gland
bulbourethral glands
Epididymis function
stores sperm and transports it from the testes
vas deferens function
transports mature sperm from the epididymis to the urethra
ejaculatory duct
tube through which semen enters the male urethra
seminal vesicles secrete
alkaline fluid
fructose
clotting proteins
(fructose and mucus)
prostate gland secretes
milky white fluid with proteins and enzymes
bulbourethral (Cowper's) glands secretes
fluid to neutralize the acidity in the urethra
FSH stimulates what in the male
spermatogenisis
LH stimulates what in the male
testosterone production
female reproductive system functions
-produce ova
-transfer ova to the fallopian tubes for fertilization
-receive sperm from the male
-provide a protective and nourishing environment for the developing embryo
embryo
the developing human organism from about 2 weeks after fertilization through the second month
external parts of the female reproductive system
labia majora
labia minora
bartholin's glands
clitoris
labia majora and minora
outer and inner skin fold, protects vaginal opening
Bartholin's glands
produce a mucus secretion to lubricate the vagina
clitoris
organ of sensitive erectile tissue anterior to the opening of the female urethra
internal parts of the female reproductive system
ovaries
fallopian tubes
uterus
vagina
ovaries function
produce oocytes
secrete hormones
fallopian tubes function
tubes through which eggs reach the uterus; fertilization usually occurs in the fallopian tubes (ampulla)
vagina
A muscular, elastic passageway that extends from the uterus to the outside of the body
Cervix
Entrance to the uterus
endometrium
inner lining of the uterus
develops due to estrogen
ovarian cycle phases
follicular phase, ovulation, luteal phase
follicular phase (ovarian cycle)
period of follicle growth (days 1-14)
stimulated by FSH
follicular cells secrete (female repro)
estrogen
estrogen proliferates
endometrium
Ovulation is induced by a peak in the secretion of
LH
luteal phase
corpus luteum develops from remants of follicle after secondary oocyte and corona radiata are ovulated.
period of corpus luteum activity (days 14-28)
corpus luteum secretes primarily
progesterone
(also estrogen)
note* estrogen and progesterone inhibit FSH and LH secretion
What hormone maintains the thickness of the endometrium during pregnancy?
progesterone
What happens if the secondary oocyte is not fertilized?
corpus luteum regresses into corpus albicans, stops secreting progesterone, follicles stop secreting estrogen.
Drop in these two hormones causes menstruation (shedding of endometrium)
uterine cycle phases
menstrual, proliferative, secretory
menstrual phase
estrogen and progesterone drop due to lack of fertilization and endometrium is shed
proliferative phase
endometrium is rebuilt due to estrogen secretion by the follicular cells
(follicles are developing due to FSH involved in ovarian cycle)
secretory phase
the phase of the menstrual cycle during which the endometrium engorges (becomes more vascular) and secretes nutrients to prepare for implantation.
hCG (human chorionic gonadotropin) function
to keep corpus luteum active and secreting estrogen and progesterone (to maintain uterine lining) until placenta can take over secretion of these hormones.
parturition
childbirth
prolactin is inhibited by what during pregnancy? why?
inhibited by high levels of estrogen and progesterone
to keep mother from lactating during pregnancy