Control of Body Function Flashcards
in evolution what does common ancestry account for?
similarities
in evolution what do adaptive modifications account for?
most differences
define speciation
process by which individuals from a single population diverge enough to be considered 2 or more distinct populations which no longer conform to a single species definition
what makes identification of species more difficult?
species hybrids which produce offspring that are fertile
define a species
populations that can no longer exchange genes/interbreed
what are the causes of species no longer being able to exchange genes/interbreed?
anatomical compatibility
behavioral isolation
spatial isolation
separated in time
what is homology?
structures which come from the same embryological origin. They do not necessarily serve the same function
what is analogy?
structures with the same function but different embryological origins
define convergent evolution
two species with similar structures that are derived from different areas but appear related/the same
define biome
worlds major communities of living things
what do biomes contain?
multiple habitats and may niches
define habitat
specific neighborhood where an animal is found
what is included within a habitat?
all living and non-living factors or conditions of the environment
define niche
environmental conditions and resources that define the requirements of a species to practice it’s way of life, particularly for its population to persist
define generalist
survive in a wide range of circumstances and make use of a variety of resources
define specialist
narrower range of conditions and resources but are able to use these more effectively than other species
what is competitive exclusion?
two species are unable to co-exist when competing for identical resources
what is evolutionary convergence?
animals in similar circumstances will evolve similar structures to solve similar problems even if the origins are very different
how is heat loss prevented in penguins feet?
counter current flow so blood in the foot is cold and then warmed by descending blood on it way back to the body. Keeps the body temperature elevated
define extinction
where a species no longer exists
what is a mass extinction event?
one where a large number of species go extinct in a short period of geological time - very rare
what is done with living species to monitor extinction?
monitored by ICUN to establish risk of extinction
what list are threatened species put on by ICUN?
red list
what are the 7 categories used by the ICUN to identify species status?
least concern near threatened vulnerable endangered critically endangered extinct in the wild extinct
what are 5 main reasons that species become extinct?
competition loss of prey human activity natural disasters climate change
what is much of the information about extinct animals gained from?
fossilisation
what can be used from fossils to suggest function?
size, shape and extent of bony features
what is prehension?
act of bringing food into the oral cavity
what are the two areas of the mouth which may be used for prehension?
lips
tongue
what cranial nerve innervates prehensile lips?
facial nerve (CNVII)
what does the facial nerve (CNVII) control?
muscles of facial expression
what cranial nerve innervates prehensile tongue?
hypoglossal nerve (CNXII)
what does the hypoglossal nerve (CNXII) control?
muscles of the tongue
what is mastication?
chewing food
what nerve controls the muscles of mastication?
trigeminal nerve (CNV)
what is salivation?
the production and secretion of saliva
what is salivary gland stimulation primarily secreted by?
parasympathetic neurons
what is salivation initiated by?
tactile stimulus in the mouth
taste
thoughts of food
sensation of hunger
what 2 cranial nerves control salivation?
facial (CNVII)
glossopharyngeal (CNIX)
what cranial nerve controls the parotid gland via the otic ganglion?
glossopharyngeal (CNIX)
how many phases are involved in swallowing?
3
what are the 3 phases of swallowing?
voluntary
pharyngeal
oesophageal
what happens during the pharyngeal phase of swallowing?
soft palate rises to block of nasopharynx
pharynx and larynx elevate to accept bolus of food
what happens during the voluntary phase of swallowing?
tongue moves bolus of food to the back of the mouth
what nerve controls the voluntary phase of swallowing?
hypoglossal nerve (CNXII)
what nerve controls the soft palate rising to block of nasopharynx during the pharyngeal phase of swallowing?
vagus nerve (CNX)
what nerve controls the pharynx and larynx elevating to accept bolus of food during the pharyngeal phase of swallowing?
glossopharyngeal (CNIX) and vagus nerve (CNX)
what do constrictors do during the pharyngeal phase of swallowing?
contract in sequence to move food bolus towards oesophagus
what nerve controls constrictors during the pharyngeal phase?
vagus nerve (CNX)
what does the epiglottis do during the pharyngeal phase?
covers opening of larynx due to force of bolus
what happens during the pharyngeal phase of swallowing to the upper oesophageal sphincter?
relaxes so bolus moves into the oesophagus
where is the enteric nervous system found?
throughout the GI tract
what do submucosal plexi regulate?
local fluid and hormone release
what do myenteric plexi regulate?
motility and muscle action
what happens during the oesophageal phase of swallowing?
food in the oesophagus stimulates the myenteric plexus
peristaltic movements move bolus to stomach
what is the gag reflex?
protective mechansim
what nerve is sensory information for the gag reflex controlled by?
glossopharyngeal nerve
what nerve is motor information for the gag reflex controlled by?
vagus
what is the role of the gag reflex?
prevents objects entering the pharynx in an uncontrolled way
what stimuli cause increased gastric secretions?
taste, smell, thought of food or feeling food in the mouth
what nerve causes increased gastric secretions?
vagus nerve
what is the effect of the vagus nerve increasing gastric secretions?
hormones are released which further increase gastric secretions (positive feedback)
what other factor increases gastric secretions?
distention of the stomach
what does distention of the stomach cause?
increased vagus stimulation which also increases secretions
what happens when chyme enters the duodenum from the stomach?
stimulation of the release of various hormones
what causes bile secretions from the liver and contraction of the gall bladder?
hormones released by presence of chyme into the duodenum
vagus nerve signalling
what do distention of the stomach and presence of chyme into the duodenum stimulate?
mass movement of contents of the bowel towards the rectum
what happens when faeces distend the rectum?
local reflexes increase contractions of the colon and rectum as well as relaxing internal anal sphincter
where does distention of the rectum send sensory signals?
sacral region of spinal cord
through what nerve does distention of the rectum send sensory signals?
pelvic nerve
what does sensory signals from the rectum to the sacral region of spinal cord cause?
colon to contract and internal anal sphincter to relax
what nerve controls the voluntary aspect of defecation?
pudendal nerve
what does the pudendal nerve control?
external anal sphincter
what tracts regulate defecation reflex centre?
descending
what nerve gives voluntary control of the external urethral sphincter?
pudendal
describe neuronal control of erection in a musculocavernous penis
sexual thoughts/mating signals or sensory stimulation of the penis stimulate the sacral region of the spinal cord
pelvic parasympathetic nerves cause vasodilation of the arteries in erectile bodies. Veins are compressed reducing outflow
what do pelvic parasympathetic nerves cause during musculocavernous erection?
pelvic parasympathetic nerves cause vasodilation of the arteries in erectile bodies. Veins are compressed reducing outflow
what do sexual thoughts/mating signals or sensory stimulation of the penis stimulate?
sacral region of the spinal cord
what type of muscle is found within retractor penis muscle?
smooth and skeletal
describe neuronal control of erection in a fibroelastic penis
decreased sympathetic tone relaxes smooth muscle allowing sigmoid flexure to straighten and erection to be achieved
when is stimulation of sympathetic centres in the spinal cord increased?
as sexual tension increases
what does increase in sympathetic centre stimulation cause during erection?
seminal vesicles and prostate to release seminal fluid
what leads to semen being present in prostatic urethra?
peristaltic contraction of ductus defrens
what is the effect of semen in the prostatic urethra?
sends sensory information to the spinal cord
what is the role of sympathetic nerves in neuronal control of ejaculation?
internal urinary sphincter closes to prevent retroejaculation or release of urine
what is the role of pudendal nerves in neuronal control of ejaculation?
cause rhythmic contraction of muscles at the base of the penis to expel semen
what are the glands of the body which secrete hormones?
pituitary pineal thyroid thymus adrenal pancreas ovaries/testis
how long does the response of hormones take and their effect last?
slower than neurons but last longer
what is the difference between exocrine and endocrine secretion?
exocrine secretions are released via duct onto skin/into organ
endocrine secretions of hormones are straight into the blood stream
what are the 3 stimulants of hormone release?
humoral - molecules in the blood
neuronal
hormonal - other hormones
which of the endocrine glands in the body also have exocrine function?
pancreas
ovaries/testis
where is the pituitary gland located?
the base of the brain
how is the pituitary gland connected to the hypothalamus?
infundibulum
what are the 2 parts of the pituitary gland?
anterior and posterior
what makes the posterior pituitary neuronal?
extension of the hypothalamus
how are hormones released from the posterior pituitary?
stimuli increases or decreases action potential in hypothalamic neurons
action potentials are conducted down neurones to the posterior pituitary
hormones stored in the axon terminals are released into the blood
give 2 examples of hormones released from the posterior pituitary
ADH
oxytocin
what sort of tissue makes up the anterior pituitary?
glandular
how are hormones released from the anterior pituitary?
hypothalamic neurones release inhibitory or releasing hormones
hormones flow through hypophaseal portal circulation to anterior pituitary
they pass into the pituitary cells and stimulate or inhibit the release of hormones into the blood
give 4 examples of hormones released from the anterior pituitary
prolactin
LH
FSH
growth hormone
what is the role of ADH?
decreases urine output by acting on kidney tubules to increase water reabsorption and so reduce plasma osmolality and increasing blood volume
how is ADH released from the posterior pituitary?
changes in osmolality or blood pressure are detected by osmo and baroreceptors
increased osmolality or decreased BP increase action potentials in ADH neurones
action potential is passed to the posterior pituitary
ADH is released into the blood
what stimulates the release of oxytocin?
stretch of uterus/cervix or stimulation of nipples
what is the role of oxytocin?
increase uterine contraction and milk release
how is oxytocin released from the posterior pituitary?
stimulation causes increase in action potentials in oxytocin neurones
action potentials pass to posterior pituitary
oxytocin is released in blood
what is the role of prolactin?
increases milk production
how is prolactin released from the anterior pituitary?
suckling baby initiates sensory nerve pathway to hypothalamus
releases hormones to the anterior pituitary leading to prolactin release
where is FSH released from?
anterior pituitary
what is the role of FSH?
stimulation of follicogenesis and oestrogen production
what does oestrogen cause?
thickening of endometrium and secretion of LH (and FSH) at the correct time
what is the role of the LH surge?
causes ovulation and corpus luteum development
what is produced by the corpus luteum?
progesterone
what is the role of progesterone?
maintains endometrium and negatively feeds back to hypothalamus and so reduces LH and FSH production
what makes ovaries endocrine organs?
release of oestrogen and progesterone
what does FSH stimulate in men?
Sertoli cells to increase spermatogenesis
what does LH stimulate in men?
interstitial cells of testis to secrete testosterone
what does testosterone stimulate?
Sertoli cells as well as developing sex organs and secondary sexual characteristics
what hormone inhibits LH and FSH release?
testosterone
what hormone inhibits FSH secretion?
inhibin
where are Leydig/interstitial cells located?
in surrounding connective tissue in testis
where are Sertoli/Sustentacular cells located?
in semiphorous tubule of the testis
where are germ cells cells located in the testis?
immature cells at the periphery and mature as the reach the lumen
what does the pineal gland manufacture and release?
melatonin
how is melatonin released from the pineal gland?
light enters the eye
signals to the hypothalamus which sends impulses via sympathetic neurones to the pineal gland
what effect does light have on pineal gland stimulation?
increased light = reduced signals
decreased light = increased signals
what is the role of melatonin?
helps control sleep/wake cycles
affects FSH and LH release from anterior pituitary
why is the pineal gland larger in sheep than in humans?
as it controls the seasonal breeding patterns
where is the thyroid gland positioned in the body?
anterior to the first few tracheal rings
what is the thyroid gland comprised of?
2 lobes connected by an isthmus
what does the thyroid gland contain?
follicles with walls made from follicular cells (simple cuboidal epithelium)
what are follicles filled with?
thyroglobulin (thyroid hormone precursor)
what cells sit between follicles?
parafollicular cells
what hormones do the follicular cells release?
T3 and T4 (thyroxine)
what hormones do the parafollicular cells release?
calcitonin
what is the role of calcitonin?
decreases Ca2+ levels in the blood
how are thyroid hormones released from the thyroid gland?
in response to stressors/hypothermia releasing hormones travel from hypothalamus to anterior pituitary
TSH is released from the anterior pituitary
what is the role of TSH?
increased synthesis of T3 and T4
what is the role of T3 and T4?
act on target tissues to increase metabolism, increase body temperature and increase normal growth and development
what reduces TSH and releasing hormone production?
negative feedback
how many parathyroid glands are there?
4 positioned on the posterior surface of thyroid gland
what do parathyroid glands secrete?
parathyroid hormone
what is the role of parathyroid hormone?
increases Ca2+ levels in the blood through action on bone, kidney and small intestine
where are the adrenal glands positioned in humans?
superior/cranial pole of each kidney
what are the adrenal glands formed of?
central medulla and outer cortex
what is released from the adrenal medulla?
adrenaline and noradrenaline
what stimulates the hypothalamus to release adrenaline and noradrenaline?
stress, physical activity and low blood sugar
how are adrenaline and noradrenaline released from the medulla?
hypothalamus is stimulated, leads to sympathetic stimulation of the adrenal medulla.
what are the effects of adrenaline and noradrenaline?
increased blood glucose
increased heart rate
increased blood flow to muscles
reduced blood flow to gut and skin
what type of hormones are released from the adrenal cortex?
steroid
what are 3 examples of hormones secreted from the adrenal cortex?
aldosterone
cortisol
androgens
when is aldosterone secreted?
when blood volume is low
what is the main role of aldosterone?
water retention to increase blood volume
what are the 2 main effects of cortisol?
increased protein and lipid breakdown and glucose production
reduced immune response and inflammation
what is the role of androgens?
responsible for male secondary sex characteristics and promotes axillary and pubic hair growth in females
where is the thymus located?
in the neck and cranial/superior thorax
what does the thymus release?
thymosin
what is the role of thymosin?
development of the immune system
what happens to the thymus as the animal matures?
it regresses
what are the 2 main functions of the pancreas?
endocrine
exocrine
what is the endocrine function of the pancreas controlled by?
ANS, digestive hormones and levels of blood nutrients
what is produced in pancreatic islets?
glucagon and insulin
where in the pancreas is glucagon produced?
alpha cells
what is the effect of glucagon?
increase blood glucose levels
where in the pancreas is insulin produced?
beta cells
what is the effect of insulin?
reduce blood sugar levels
what is involved in the exocrine function of the pancreas?
exocrine cells secrete digestive enzymes
what is the role of gastrin?
increases stomach secretions
what is the role of secretin?
decreases gastric motility and secretions
what effect does secretin have on the pancreas?
stimulates production of alkaline secretions
what is gastrin release stimulated by?
distention of the stomach and presence of digesta
what is the role of cholecystokinin?
decreases gastric motility
what effect does secretin have on the liver?
increases bile secretion
what effect does cholecystokinin have on the pancreas?
stimulates release of gastric enzymes
what effect does cholecystokinin have on the gallbladder?
stimulates release of bile from gall bladder
what is the origin of a muscle?
attachment to the stationary end of a muscle
what is the belly of a muscle?
thicker middle region of muscle
what is the insertion of a muscle?
attachment to the mobile end of muscle
how can the muscle action be predicted?
origin and insertion
joints and regions the muscle crosses
muscle fibre orientation
what can functional muscle groups/compartments tell us?
about innervation as each group/compartment is innervated by specific nerves
what can functional muscle groups/compartments be catergorised by?
location or function
what are the 4 compartments of the upper/thoracic limbs in anatomical position?
anterior compartment of upper arm
posterior compartment of upper arm
anterior compartment of forearm
posterior compartment of forearm
what is the function of the anterior compartment of upper arm?
elbow flexors
what is the function of the posterior compartment of upper arm?
elbow extensors
what is the function of the anterior compartment of forearm?
carpal and digit flexors
what is the function of the posterior compartment of forearm?
carpal and digit extensors
what are the 5 compartments of the lower/hind limbs (pelvic limbs)?
anterior compartment of the thigh medial compartment of the thigh posterior compartment of the thigh anterior compartment of the leg posterior compartment of the leg
what is the function of the anterior compartment of the thigh?
knee (stifle) extensors
what is the function of the medial compartment of the thigh?
thigh adductors
what is the function of the posterior compartment of the thigh?
knee (stifle) flexors
what is the function of the anterior compartment of the leg?
dorsiflex the ankle (flex hock) and extend digits
what is the function of the posterior compartment of the leg?
plantiflex the ankle (extend hock) and flex digits
what are dermatomes?
area of skin supplied by one single pair of spinal nerves
what are myotomes?
group of muscles supplied by one single pair of spinal nerves
what are spinal cord swellings also known as?
intumescence
where on the spinal cord is it enlarged?
cervical and lumbosacral region due to limbs
what does plexi mean?
network
what are the 2 main plexi in the body?
brachial plexus
lumbosacral plexus
where does the sciatic nerve originate?
lumbosacral plexus
what part of the leg does the sciatic nerve innervate?
posterior compartment of thigh
what muscles does the sciatic nerve innervate?
knee and stifle flexors
what part of the leg does the obturator nerve innervate?
medial thigh
what muscles does the obturator nerve innervate?
adductors of thigh
what part of the leg does the femoral nerve innervate?
anterior compartment of thigh
what muscles does the femoral nerve innervate?
knee/stifle extensors
what part of the thoracic limb does the musculocutaneous nerve innervate?
anterior compartment of upper arms
what muscles does the musculocutaneous nerve innervate?
elbow flexors
what part of the leg does the fibular/peroneal nerve innervate?
anterior compartment of leg
what muscles does the fibular/peroneal nerve innervate?
flexor of hock and extensor of digits
what part of the leg does the tibial nerve innervate?
posterior compartment of leg
what muscles does the tibial nerve innervate?
extensor of hock and flexor of digits
what part of the thoracic limb does the radial nerve innervate?
posterior compartment of upper arm
what muscles does the radial nerve innervate?
extensors of elbow
what part of the thoracic limb does the medial/ulnar nerve innervate?
forearm/hand and distal forelimb
what muscles does the medial/ulnar nerve innervate?
flexors of carpus and digits
what is the role of the prefrontal area of the brain?
controls motivation and foresight to plan and initiate movements
what is the role of the premotor area of the brain?
organising motor functions before they are initiated in the primary motor cortex
what is the role of the primary motor cortex in the brain?
initiation and control of voluntary movements
what is the name of the landmark in the brain that the primary motor cortex is rostral to?
central sulcus
what is the central sulcus known as in dogs?
cruciate sulcus
where are upper motor neurones located?
completely contained within the CNS
where are the cell bodies of upper motor neurones located?
in the cerebral cortex
what is the role of upper motor neurones?
initiate voluntary movement
maintain muscle tone
regulate posture
where do lower motor neurones run to?
skeletal muscle
where are the cell bodies of lower motor neurones located?
ventral horn of spinal cord or cranial nerve nuclei
where do the axons of lower motor nerves project into?
PNS via cranial or spinal nerves
where do lower motor neurones connect with muscle?
neuromuscular junction
what are descending tracts?
pathways by which motor signals are sent from the brain to lower motor neurons
what are ascending tracts?
pathways by which sensory signals are sent from sensory receptors to the brain
what do descending tracts contain axons from?
cerebrum or cerebellum
what are the 2 groups of descending tract?
pyramidal system
extra-pyramidal system
where do the pyramidal systems run through?
medullary pyramids
what is controlled by pyramidal systems?
complex, learned, voluntary movements
high degree of fine motor control
what is controlled by the extrapyramidal system?
maintaining and changing posture
rhythmical activities
semi-automatic activities (e.g. feeding)
what is the role of the cerebellum and basal nuclei?
regulate motor systems to ensure coordinated action
what are the main areas controlled by the cerebellum?
posture
muscle tone
balance
fine motor coordination (comparance)
planning and practicing rapid, complex motor actions
coordination of all somatic motor activities
in what species is the cerebellum:cerebrum ratio smaller?
animals with complex gait cycles
what are the basal nuclei formed of?
functionally related nuclei in the cerebrum , diencephalon and midbrain
what is the individual role of the basal nuclei?
planning, organising and coordinating, movement/posture
what does the basal nuclei form with other areas of the CNS?
stimulatory and inhibitory feedback loops
is the basal nuclei involved with balance?
no
