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76 Cards in this Set

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What are the 2 main control systems?
Nervous

Endocrine
What are a few differences between the nervous and endocrine systems?
Nervous - rapid response via action potentials and neurotransmitters, controlled consciously or subconsciously

Endocrine - slower more prolonged response,uses hormones and feedback loops
If we cut the cerebrum in half what can you see?
the Cerebral cortex
Explain the cerebral cortex
2-4mm of grey mater
follows contour or gyri and sulci
increases amount of grey mater for given area
conscious thought and recognition of stimuli
What are the steps in sensory response?
receptor
sensory/afferent neuron
CNS for integration
spinal cord - sensory tracts
brain - cerebral cortex, parietal/occipital/temporal lobe
conscious awareness of stimuli
What are the steps in motor response?
cerebral cortex - conscious decision to move, frontal lobe
spinal cord - motor tracts descending
motor -efferent
How does the sensory enter the spinal cord?
via the dorsal nerve root
How does the motor exit the spinal cord?
via the ventral nerve root
Spinal cord tracts are either....
ascending or descending
Ascending is associated with what?
sensory
Descending is associated with what?
motor
What do the tracts of the spinal cord do?
take info up or down the spinal cord
Where does the spinothalamic tract take info?
spinal cord to the thalamus
Where does the corticospinal tract take info?
cerebral cortex to spinal cord
Where does the Spinocerbellar tract take info?
Spinal cord to cerebellum
What is a reflex?
involuntary response to a stimuli
rapid, predictable and unlearnt
uses a specific neural pathway
minimal processing
cannot be improved by repetition
What is the neural pathway a reflex takes?
reflex arc
What is a reaction?
voluntary response to stimuli
slower, lots of neural processing
not predictable
can be improved with practice
What are the 5 basic components to a reflex arc?
1. sensory receptor detects stimuli
2. sensory neuron conducts action potentials through nerve and dorsal root of SC
3. in the SC sensory neuron synapses with an interneuron
4. the interneuron synapses with a motor neuron
5. a motor neuron axon conducts action potentials through the ventral root and SN to the effector organ
What are the 2 classifications of reflexes?
Somatic
Autonomic
What is a monosynaptic
one synapse
What is a polysynaptic?
a synapse with one or more interneurons
What muscle do Somatic reflexes deal with?
skeletal muscle
What is the purpose of somatic reflexes?
remove body from painful stimuli
keep balance
SC or brain as the integration center
What are the names of a few somatic reflexes?
Stretch reflex
Golgi tendon reflex
withdrawal reflex
crossed extensor reflex
What do autonomic reflexed involve the control of?
smooth muscle
cardiac muscle
body viscera
What is autonomic reflex used for?
maintaining body function e.g. HR, BP blood CO2 levels
movement of food through gut
defecation and micturition reflex
The brainstem is composed of 3 parts, name them
Medulla Oblongata
Pons
Midbrain
Damage to the brainstem can cause death, T or F?
True
explain the medulla oblongata
Most inferior part of brainstem and is a continuation of SC
lots of white matter - ascending and descending tracts
lots of nuclei for integration - regulates HR, BVD, respiratory, hiccups, coughing, sneezing, swallowing, vomiting
explain the pons
bridge between medulla/midbrain and cerebellum
sleep centre for REM
pontine respiratory centre
explain the midbrain
between the pons and diencephalon
has important nuclei for movement
reflex areas include superior and inferior colliculli
What is superior colliculli for?
visual, coordinates head and eye movements
What is inferior colliculli for?
auditory, startle reflex turn head towards sound
What are the 3 parts to the diencephalon?
Thalamus
Hypothalamus
Epithalamus
explain the hypothalamus
important in homeostatic mechanisms
autonomic control,
regulates body temp, sleep-wake cycles, food intake, water balance and thirst
regulates pituitary secretions
The hypothalamus is the link to the endocrine system through which gland?
pituitary gland
What is the pituitary gland joined to the hypothalamus by?
infundibulum or pituitary stalk
how many parts is the pituitary gland divided into?
2
How big is the pituitary gland?
pea size
What are the 2 parts of the pituitary gland called?
Anterior - (adenohypohysis) grows from roof of mouth and made from glandular cells
Posterior - (Neurohypophysis) down growth from brain is neural tissue
explain the Anterior pituitary (AP) in more detail
made from glandular tissue
secretes 7 hormones in response to releasing/inhibiting hormones from hypothalamus
releasing factors travel to AP via a network of capillaries called hypothalamohypophyseal portal system
this stimulates cells in AP to secrete hormones into blood
What are the 7 hormones of the AP and what are their target tissue?
Growth Hormone (GH) - most body tissue
Thyroid stimulating hormone (TSH) - thyroid gland
Andrenocorticotropic Hormone (ACTH) - Adrenal gland cortex only
Follicle stimulating Hormone (FSH) - Ovaries and testis
Luteinizing Hormone - ovaries and testis
Prolactin - Ovaries and mammory glands
Melanocyte-stimulating hormone (MSH)- skin cells
How many hormones does the Posterior Pituitary (PP) secrete?
2, hormones made in cell bodies located in hypothalamus are transported down middle of axons to be released from PP in a process called neural secretion
axons tract down through what?
infundibulum/ pituitary stalk
What is this tract of axons called?
hypothalamohypophysial tract
Where are the PP hormones made?
in the hypothalamus
What are the 2 main groups of cell bodies in the hypothalamus?
Supraoptic nuclei
paraventricular nuclei
explain the supraoptic nuclei
above optic chiasma
produces antidiuretic hormone (ADH)
stimulates kidneys to retain H2O
explain the paraventricular nuclei
parallel to ventricles
produce oxytocin
influence on smooth muscle, uterus and mammary glands
What are the 3 types of communication for the endocrine system?
Autocrine
paracrine
Endocrine
What cells do the autocrine cells affect?
same cells that secrete them
What cells do the paracine cells affect?
nearby cells
What cells do the endocrine cells affect?
cells distant to source
what is the differnce between endocrine and exocrine glands?
endocrine glands are ductless
exocrine have ducts to secrete non hormonal products
What are the 3 types of chemical hormones?
amino acid based
steroid based
eicosanoids
explain which chemical hormones are water soluble and where they are made
Amino acid based - water soluble exempt hormones secreted by thyroid gland, made from AA, peptides, protein
Steroid based - lipid soluble, made from cholesterol
Eicosanoids - lipid soluble, made from fatty acids
What does the chemical composition determine?
how they are transported
how they affect target tissue
explain water soluble hormones
dissolve in plasma
travel as free hormones
degrade rapidly
have short half life
explain lipid soluble hormones
must bind to protein
keeps confined in blood
process of binding is reversible, releases hormone in the tissues where needed
Hormones attach to receptors or ____________ of their target cells
binding sites
Where can receptors be?
inside the cell
on the membrane of target cell
What are the 3 things that hormones and change/activate?
change the activity of the organelles - increase production of mitochondria/ribosomes
change the cell membrane permeability - increase uptake of something
activate a particular cell mechanism - increase/decrease production
How do we get changes to occur in the cell?
indirectly - via cell mediator/second messenger
directly - influencing DNA
Which method is used depends on the what of the hormone?
membrane solubility
What method do non lipid soluble hormones have to use?
indirect as can't get through lipid bilayer of membrane

e.g. most AA and proteins
What method do lipid soluble hormones have to use?
direct

e.g steroids, thyroid hormones
explain the indirect method of hormone action- second messenger mechanism.
Hormone is the first messenger outside cell
cell has receptors on outside of membrane
hormone attaches to receptor
activates G protein
Adenyl-cyclase converts ATP------>cAMP
cAMP acts as second messenger
cAMP is degraded and effects stop
to continue need more hormone
NON LIPID SOLUBLE
explain direct messenger mechanism
hormone can get through membrane
attatches to receptor inside cytoplasm
both hormone and receptor complex pass nucleus
activates specific genes
steroid hormones
What are the 3 stimuli that control hormone release?
Humoral stimuli
Neural stimuli
Hormonal stimuli
explain humoral stimuli
secrete in direct response to changing blood levels
e.g parathyroid (Ca++)
explain neural stimuli
nerves can directly stimulate
less common
e.g. adrenal medulla (sympathetic)
explain hormonal stimuli
in response to hormones by other endocrine organs
explain negative feedback loop
as concentration of Y increases this feedbacks to gland B which in turn increases the secretion of hormone X which reduces the levels of Y. a rising level of Y triggers the response to reduce levels of Y
Do most hormones use a negative feedback loop?
Yes
explain positive feedback loop
hormone secretion continues when increase levels of hormone/substance
reinforces the secretion and therefore reinforces effect
e.g. labor, milk ejection, blood clotting