Nervous System and Endocrine System Flashcards
exocrine gland
- secrete into a duct that carries the secretion to the body surface/body cavities
eg. sweat glands, mucous glands, salivary glands
endocrine gland
- secrete hormones into the extracellular fluid that surrounds the cells that make up the gland
- usually passes into capillaries to be transported by blood
eg. pinel, thyroid, parathyroid, pancreas, testes, ovaries, adrenal, thymus, hypothalamus
hormones
- proteins, steroids or amines
- may affect all cells of the body or only particular groups (target cells) or particular organs (target organ)
protein/amine hormones
- work by attaching to receptor proteins in the membrane of the target cell
- hormone and receptor combining causes secondary messengers substance to diffuse through a cell and activate particular enzyme
- lock and key
- limited # of receptors in each membrane
steroid hormones
- work by entering target cells and combining with a receptor protein inside the cell
- may be in mitochondria/nucleus
- hormone-receptor complex activates the genes controlling the formations of particular proteins
hormones may…
- activate certain genes in the nucleus so that a particular enzyme or structural proteins is produced
- change in shape or structure of an enzyme so that is is turned ‘on’ or ‘off’
- change the rate of production of an enzyme or structural protein by changing the rate of transportation or translation during protein production
enzyme amplification
- a series of chemical reactions in which the product of one step is an enzyme that produces an even greater number of product molecules
hormone clearance
- turning off hormone is done by breaking it down
- can be done in target cells, but also liver and kidney
- excreted in bile or urine
control of hormone secretions
- regulated by negative feedback systems whereby the response produced by the secretion of the hormone is the opposite of the stimulus that caused the secretion
- some involve release of regulating factors from hypothalamus/brain (regulate function of pituitary gland)
hypothalamus
- located at base of brain
- regulates many basic functions eg. body temp, water balance, heart rate
- many functions carried out through pituitary gland
- produces many hormones
- some carried by the blood to anterior lobe of the pituitary gland, where they stimulate/inhibit the release of hormones made in the anterior lobe
- others pass along nerve fibres from hypothalamus to posterior lobe of pituitary where they are then secreted
pituitary gland
- lies just under hypothalamus and is joined to hypothalamus by a stalk called INFUNDIBULUM
- vital for normal functioning
- consists of anterior and posterior lobes
anterior lobe of pituitary
- front
- no nerved connecting it to the hypothalamus but connected by complex network of blood vessels
- controlled by releasing and inhibiting factors secreted by the hypothalamus (secreted into extracellular fluids around cells of the hypothalamus and carried by blood to the anterior lobe)
posterior lobe of pituitary
- hormones not manufactured here
- produced in special nerve cells in the hypothalamus of the brain
- cells have long extensions that pass through infundibulum to posterior lobe
- hormones move down extensions and stored ready for release into bloodstream
- release of hormone triggered by nerve impulses
follicle-stimulating hormone
ovaries: growth of follicles
testes: production of sperm
luteinising hormone
ovaries: ovulation and maintenance of corpus lutem
testes: secretion of testosterone
growth hormone
all cells: growth and protein synthesis
thyroid stimulating hormone
thyroid: secretion of hormones from thyroid
adrenocorticotropic hormone
adrenal cortex: secretion of hormones from the adrenal cortex
prolactin
mammary glands: milk production
antidiuretic hormone
kidneys: reabsorption of water
oxytocin
uterus: contractions of uterus during childbirth
mammary glands: release milk
the pineal gland
- found deep inside brain
- unknown role
- secretes melatonin
melatonin
regulates sleep patterns
thyroid gland
- located in neck
- 2 lobes on either side of trachea joined by a narrow piece of tissue
- thyroxine secreted (consists of iodine and amino acids)
thyroxine
- controls body metabolism by regulating reactions in which complex molecules are synthesised from simple ones
the parathyroid glands
- embedded in the rear surface of the lobes of the thyroid gland
parathyroid hormone
- controls calcium and phosphate levels in the blood
the thymus
- located in chest, just above hear and behind sternum
- secretes thymosins (influence maturation of disease-fighting cells)
the adrenal glands
- 2 glands; one above each kidney
- each had inner adrenal medulla and an outer adrenal cortex
adrenal medulla
- produces adrenaline and noradrenaline
adrenaline
- prepares body for fight/fight
noradrenaline
- increases rate/force of heartbeat
adrenal cortex
- 20+ hormones produces
aldosterone
- acts on kidney to reduce amount of Na and increase about of K in urine
cortisol
- promotes normal metabolism
- helps body withstand stress
- repair damaged tissues
the pancreas
- lies just below stomach/alongside duodenum
- both exo and endocrine gland
- exocrine part secretes digestive enzymes into the small intestine through pancreatic duct
- islets of lagerhands are the endocrine part of pancreas
insulin
- reduces amount of glucose in blood
- promotes uptake of glucose in the blood by the cells of the body
- determines by amount of sugar in the blood and is controlled through neg feedback systems
glucagon
- increases amount of glucose in blood
- promotes breakdown of glycogen to glucose in liver
the gonads
- testes or ovaries
- produce hormones as well as eggs/sperm
androgens
- male sex hormones
- responsible for development/maintenance of male sex characteristics
oestrogens
- female sex hormones
- responsible for development/maintenance of female sec characteristics
- regulates menstruation/pregnancy changes
nervous system
- the communication network and control centre of the body
- involved in maintaining constant environment inside the body
central nervous system
- brain/spinal cord
- control centre for NS
peripheral nervous system
- nerves that connect CNS with receptors, muscles, glands
nerve cells
- neurons
- basic structural and functional units of the whole nervous system
- neurons in brain and many in spinal cord are interneurons
interneurons
they have many branches that are able send or receive to or from adjacent neurons
dendrites
- fine short extensions of cytoplasm
- carry messages into the cell body
axon
- single, long extensions
- carry message away from the cell body
myelin sheath
- a white fatty sheath that surrounds some nerve fibres
nerve fibre
- any long extension of a nerve cell
grey matter
- consists of nerve cell bodies and unmyelinated fibres
white matter
- myelinated fibres
schwann cells
- a cell that wraps around a nerve fibre, forming the myelin sheath
nodes or ranvier
- a gap in the myelin sheath or a nerve fibre
functions of sheath
- acts as insulator
- protects the axon from damage
- speeds up the movement or nerve impulses
sensory (receptor)
- carry messages from receptors in the sense organs, or in the skin to the CNS
motor (effector)
- carry messages from CNS to muscles and glands
multipolar
- have 1 axon
- multiple dendrites extending from cell body
- most common
- most interneurons and motor
bipolar
- have 1 axon
- have 1 dendrite
- both may have extensions at their ends
- eye, ear, nose (impulses taken from receptor cells to other neurons)
unipolar
- 1 extension; axon
- cell body to one side of axon
- most sensory neurons that carry messages to spinal cord
synapses
- junction between the branches of adjacent neurons
- occur because axon or one nerve and dendrite of other
nerve impulses
- nerve impulse is an electrochemical change that travels along a nerve fibre
- speed depends on myelinated/unmyelinated and diameter of fibre
nerve impulses: action potential
- slow depolarisation of the membrane brings the potential to threshold
- sodium channels in the membrane open; sodium ions flood into the cell; membrane becomes depolarised; membrane voltage rises
- sodium channels close and membrane becomes repolarised
- membrane returns to resting state
- refractory period; brief time afterwards, the part of the nerve fibre cannot be stimulated to respond again
conduction along unmyelinated fibres
- depolarisation of one area of the membrane causes a local current flow between neighbouring areas on the membrane
- current flow causes depolarisation immediately adjacent to the site of original stimulus
- repairs so action potential moves away from point of stimulus
- refractory period prevents stimulus from travelling backward
transmission along myelinated fibres
- nerve cells insulated from extracellular fluid except at the nods of ranvier
- ions can’t flow in/out and action potential can’t be formed
- action potential jumpers from one nod of ranvier to another
transmission across synapse
- neurotransmitters released at end of axon and diffuse across gap and attach to receptors on the membrane of the next
- only from axon to dendrite or axon to cell body
Divisions of NS
- pns consists of nerve fibres which carry info to and from cns and groups of nerve cell bodies (ganglia) which lie outside the brain and spinal cord
- 12 pairs of nerves arise from brain; cranial; mixed
- 31 pairs of nerves arise from spinal cord; mixed and joined to spinal cord by 2 roots
ventral root
- contains axons of motor neutrons that have their cell bodies in the grey matter of spinal cord
dorsal root
- contains the axons of sensory neurons that have their cell bodies in a small swelling on the dorsal root (dorsal root ganglion)
effectors
autonomic vs somatic
auto: heart muscle, involuntary muscle, glands
som: skeletal (voluntary) muscle
general function
autonomic vs somatic
auto: adjustment of the internal environment
som: response to the external environment
neurotransmitter at effector
autonomic vs somatic
auto: acetylcholine or noradrenaline
som: acetylcholine
efferent (outward) pathway
autonomic vs somatic
auto: two nerve fibres from CNS tot he effector with a synapse in a ganglion
som: one nerve fibre from the CNS to the effector; no synapse and no ganglion
control
autonomic vs somatic
auto: involuntary (automatic)
som: voluntary (senses)
effect on target organ
autonomic vs somatic
auto: 2 sets (sympathetic/parasympathetic)
som: 1 set
nature of message
NS vs ES
N: electrical impulses and neurotransmitters
E: hormones
transport of message
NS vs ES
N: along membrane of neurons
E: by the blood stream
cells affected
NS vs ES
N: muscle and gland cells; other neurons
E: all body cells
type of response
NS vs ES
N: local and specific
E: may be very general and widespread
time takes to respond
NS vs ES
N: rapid
E: slower
duration of response
NS vs ES
N: brief; stops when stimulus stops
E: long lasting; may continue long after stimulus has stopped
protection of CNS
- bone
- membrane (meniges)
- cerebrospinal fluid
3 layers of connective tissue forming membranes around CNS
- outer layer: tough/fibrous
- middle layer: loose mesh of fibres
- inner layer: much more delicate
cerebrospinal fluid
- occupies space between middle and inner layers or meniges
- circulates through cavities
- clear, watery
- acts as shock absorber
- supports the brain (floats)
- circulates nutrients to cells of brain
the cerebrum
- biggest part
- outer surface
- below is white matter
longitudinal fold
convolutions
sulci
longitudinal fold
a deep cleft that almost separates the cerebrum into two halves
convolutions
folds of the surface of the cerebrum
sulci
shallow downloads of the surface of the cerebrum
functions of cerebrum
- thinking, reasoning, learning, memory, attention, responsibility
functional areas of brain
sensory - interpret impulses from receptor
motor - control muscular movement
association - concerned with intellectual/emotional responses
sensory areas
- receive and process nerve impulses from sense
motor areas
- send impulses to muscles (voluntary)
association areas
- interpret information from senses and make it useful
the corpus callosum
- wide band of nerve fibres that lie under cerebrum
- allow two halves to communicate
cerebellum
- posture, balance, fine coordination
- receives sensory info from inner ear and stretch receptors in skeletal muscles
- take place below conscious level
hypothalamus
- homeostasis
- regulation of heart, digestive system, appetite, thirst, metabolism, body temp, response to fear/anger
medulla oblongata
- regulates the hear (cardiac centre)
- regulates breathing (respiratory centre)
- regulates diameter of blood vessels (vasometre)
spinal cord
- pathway for communication between muscles and glands and brain
- integration of automatic/protective reflex
ascending; sensory axons; messages up towards brain
descending; motor axons; messages down away from brain
receptors
- a structure that is able to detect a change in the body’s internal or external environment
- some of a particular type are grouped together in a sense organ eg. light in eye
- others are simple nerve endings and may be spread through parts of the body/whole body e.g. pain/temp receptors in the skin
thermoreceptors
- able to respond to heat/cold
- inform brain of temp changed outside body
- info received by the hypothalamus and cerebrum so continually aware of changes
- skin thermoreceptors are nerve endings that are sensitive to cold or hot but not both
- temp inside body is monitored by thermoreceptors in the hypothalamus; detect temp of the blood through the brain
osmoreceptors
- osmotic pressure; is determined by the concentration of substances dissolved in the water of the blood plasma
- located in the hypothalamus and are sensitive to osmotic pressure
- respond to small changes in OP and are able to stimulate the hypothalamus so that the body’s water content is maintained within very narrow limits
chemoreceptors
- stimulated by particular chemicals
- present in nose and mouth
- internal chemoreceptors are sensitive to body fluids
- important because sensitive to pH and O and CO2 conc
- involved in regulation of the heartbeat and breathing
touch receptors
- mainly in the skin
- some close to the surface
- these occur in greater conc. in lips, fingertips, eyelids, external genital organs
- nerve endings also associated with the base of each hair follicle
- respond to light touch
- adapt rapidly - after short period of time we are no longer aware of the touch
