Revision Flashcards
Negative feedback
- blood pressure drops
- brain detects change, signals heart to inc HR + constrict blood vessels
- pressure restored
Positive feedback
- blood pressure drops
- blood flow to heart dec
- heart unable to pump enough blood to maintain pressure
- blood flow to cardiac muscles decrease
- pressure decreases further
CNS
- brain and spinal cord
- intergrative and control centres
PNS
- cranial nerves and spinal nerves
- communication lines between the CNS and rest of body
sensory (afferent) div
- somatic and visceral sensory nerve fibres
- conducts impulses form receptors to the CNS
motor (efferent) division
- motor nerve fibres
- conducts impulses from the CNS to effectors (muscles and glands)
Autonomic nervous system (ANS)
- visceral motor (involuntary)
- conducts impulses from the CNS to cardiac muscles, smooth muscles and glands
Somatic nervous system
- somatic motor (voluntary)
- conducts impulses from the CNS to skeletal muscles
Sympathetic division
- mobilises body systems during activity
Parasympathetic division
- conserves energy
- promotes housekeeping functions during rest
- local potentials
- usually generated in the neurons dendrites accumulate and reach the trigger zone of the axon
- action potential
- trigger zone depolarises to threshold and generates an AP
action potential propagation
- the AP is propagated down the axon to the axon terminals
astrocyte
- anchor neurons and blood vessels
- regulate extracellular environment
- facilitate formation of blood brain barrier
- repair damaged tissue
ogliodendrocyte
- myelinate certain axons in CNS
microglial cell
- act as phagocyte
ependymal cell
- line cavities
- cilia circulate fluid around brain and spinal cord
- some secrete this fluid
absolute refractory period
membrane potential -70→ 30
- Na+ channels activated
- K+ channels activating slowly
30 → -70
- Na+ channels inactivated
- K+ channels avtivated
relative refractory period
- Na+ channels in resting state
- K+ channels remain activated
acetylcholine
- acetyl-CoA & choline
- excitatory
- CNS: brain and spinal cord
- PNS: neuromuscular junction and ANS
catecholamines (norepinephrine, epinephrine, dopamine)
- tyrosine
- excitatory
- CNS: brain and spinal cord
- PNS: ANS (symp. div)
AP propagation - myelinated axons
- more energy sufficient - reliable
- SALATORY CONDUCTION: insilating prop. of myelin sheath inc. efficiency & speed
- AP propagates from 1 node of ranvier to next by generating currents that open ion channels
AP propagation - unmyelinated axons
- passive, slow & unreliable
- ionic current flows across each adjacent segment of membrane
- step by step depolarisation & repolarisation of each voltage gated ion channel in membrane
Cerebrum
- frontal, parietal, temporal, occipital lobes
- higher mental functions
diencephalon
- thalamus, hypothalamus, epi & sub thalamus
- maintains HOMEOSTASIS
cerebellum
- coordination & movement
brainstem
- diencephalon, midbrain, pons, & medulla oblongata
- helps maintain homeostasis, responsible for some reflexes
Sympathetic nerve fibres
- thoracic and lumbar spinal cord
- short preganglioic: acetylcholine
- long postganglionic: norepinephrine
Parasympathetic nerve fibres
- brainstem or sacral spinal corn
- long preganglionic
- short postganglionic
- both acetylcholine
spinal cord and reflex arc
- PNS detects stimulus and delivers stimulus to CNS
- CNS integrates information
- PNS delivers motor response to effector organs
pulmonary circuit
- right side of heart receives deoxygenated blood from body & pumps to lung for gas exchange
- oxygenated blood returns to left side of heart
systemic circuit
- left side of heart receives oxygenated blood from the lungs and pumps to body
- deoxygenated blood returns to right side of heart
heart conducting system 1
Sinoatrial (SA) node generates an action potential, which spreads to atrial cells and the atrioventricular (AV) node
heart conducting system 2
After AV node delay, the AP is conducted to the AV bundle then to right and left branches
heart conducting system 3
AP spreads from the bundle branches along the Purkinje fibres to the contractile cells of the ventricles
P wave
atrial depolarisation
QRS complex
ventricular depolarisation (masking atrial repolarisation)
T wave
ventricular repolarisation
R-R interval
entire duration of a cardiac AP
P-R interval
duration of atrial repolarisation and AV node delay
Q-T interval
entire duration of a ventricular AP
Preload
- length or degree of stretch of sarcomeres in ventricular cells before they contract
- determined by vol of blood coming in from the pulmonary
Frank-starling law
increased ventricular muscle cells stretch, leads to more forceful contraction
afterload
- force that right and left ventricles must overcome in order to eject blood into respective arteries
- determined by pressure in systemic circuit
contractility
- hearts intrinsic pumping ability, or ability to generate tension
- determined by the heart’s intrinsic pumping ability
systemic blood pressure
- pumping of heart generates blood flow
- pressure arises from resistance
- systemic BP is highest in the aorta and declines until it reaches 0 at the right atrium
- most pronounced change in BP occurs in arterioles
factors regulating blood pressure - peripheral resistance
Peripheral resistance
- blood vessel length
- vessel diametre
- blood viscosity
- obstruction in vessels
Response to low BP & vol
- Sympathetic nerve fibres release epinephrine and norepinephrine
- ADH & renin-angiotensin- aldosterone system (RAAS) help inc BP & vol
response to high BP & vol
- sympathetic input to heart and blood vessel is inhibited
- ANP reduces BP & vol
Type I alveolar cells
90% of cells in alveolar wall,
- very thin → allows for RAPID diffusion of gases → huge surface area; inc gas exc efficiency
Type II alveolar cells
- 10% of the cells - synthesis of SURFACTANT → reduces surface tensions on alveoli
Macrophages
mobile phagocytes derived from bone marrow; clean up & digest derbris that made its way into alveolus
pulmonary ventilation
- inspiratory muscles contract
- thoracic vol inc
- lung vol inc
- interapulmonary pressure decreases to below atmospheric pressure
- air flows into lungs
Boyle’s law
Relationship between pressure and volume
Dalton’s law
- Law of partial pressures
- Total pressure = sum of all partial pressure of a gaseous mixture
Henry’s law
Degree to which a gas dissolves in a liquid is proportional to both its partial pressure and its solubility in liquid
Charles’ law
When temp inc. so does pressure of a gas
Response to inc. aretrial P CO2
- CO2 and/or H+ inc above normal range
- central chemoreceptors detect inc. in PCO2and/or H+
- chemoreceptors relay info to the DRG which stimulates VRG
- VRG triggers hyper-ventilation & additional CO2 is lost
skeletal muscle
contractions move body by pulling on bones - voluntary
cardiac muscle tissu
contractions in heart propel blood through vessels
smooth muscle tissue
contractions move fluids and solids along digestive tract and regulate the diametres of small arteries
Excitation-contraction coupling
- end-plate potential stimulates an action potential
- the AP is propagated down T-tubules
- T-tubule depolatisation leads to opening of Ca2+ channls in SR, Ca2+ enter the cytosol
ATP and the powerstroke 1
- energy from ATP breakdown places myosin into loaded or ‘cocked’ position
ATP and the powerstroke 2
- myosin head binds to active sites
ATP and the powerstroke 3
- ADP+P is released from myosin head causeing ‘powerstroke’ where myosin head uses stored energy to return to resting position
ATP and the powerstroke 4
- ATP attaches to myosin head, detaching from active site
ATP and the powerstroke 5
- attached ATP is then broken down/ hydrolysed to place the myosin head back into loaded position
Excitation
ACh triggers an end-plate potential in the motor end-plate
excitation-contraction coupling
resulting AP in the sarcolemma travels down the T-tubules and triggers Ca2+ release from the SR into cytosol
prep for contraction
Ca2+ bind to troponin, which moves tropomyosin away from active sites of actin
contraction
- actin and myosin bind, and myosin undergoes a powerstroke
- ATP detaches actin and myosin, and the cycle repeasts, leading to contraction of the muscle fibre
relaxation
- neurons stops releasing ACh, and the AChE degreades the ACh in the synaptic cleft
- cytosolic conc. of Ca2+ returns to the resting level. active sites of actin are blocked, muscle fibre relaxes
mechanisms of action - hydrophilic
- hydrophilic hormone (1st messenger) binds to its receptor in the plasma membrane
- receptor activates a peripheral protein
- peripheral protein activates an enzyme
- enzyme catalyses formation of a second messenger
- second messenger initiates a series of events in the cell that leads to changes in its activity
mechanisms of action - hydrophobic
- hydrophobic hormone diffuses into the target cell
- hormone binds to an intracellular receptor and enters the nucleus of the cell
- hormone-receptor complex interacts with the DNA to initiate a cellular change
Regulation of hormone secretion - hormonal stimuli
- growth hormone-releasing (GHRH) stimulates secretion of growth hormone (GH) from an anterior pituitary cell
- HORMONAL INHIBITION: somatosatin inhibits secretion of growth hormone from an anterior pituitary cell
Regulation of hormone secretion - humoral stimulus
Glucose uptake by a pancreatic cell triggers insulin secretion
Regulation of hormone secretion - neural stimulus
Sympathetic neruons stimulate secretion of epinephrine and norepinephrine from an adrenal medulla cell
Hypothalamus and anterior pituitary gland FB
- 1st cont: hypothalamus releases hormones
- 2nd cont: anterior pituitary releases hormone
- 3rd cont: target organs release hormones
- effects:
hormone lvl inc.
effects on other cells - return to normal range
Thyroid and parathyroid glands FB
- stimulus: exposure to cold
- receptor: receptors in hypothalamus detect change
- 1st cont : hypothalamus release TRH
- 2nd cont: anterior pituitary secretes TSH
- 3rd cont: Produce T3& T4/ secrete T3&T4 in blood
- effects: increased levels of T3&T4 in blood → inc metabolic rate
thymus
Releases thyroid hormones (T3, T4, cell growth & protein production) and CALCITONIN (reduces blood calcium levels)
parathyroid gland
releases PARATHYROID HORMONE (inc blood calcium levels)
Adrenal glands - CORTISOL
increase nutrients in blood stream
Adrenal glands - ALDOSTERONE
increase sodium reabsorption in kidney
Adrenal glands - ANDROGENIC STEROIDS
can affect gonads and other tissues
Adrenal glands - EPINEPHRINE & NOREPINEPHRINE
sympathetic effects
Blood glucose regulation - insulin
- stimulus: Blood glucose level rises
- beta cells of pancreas release insulin into the blood
→ INSULIN - liver takes up glucose and stores as glycogen
- blood glucose level decline
proximal convoluted tubule
- reabsorb nutrients from filtrate
Loop of henle
- establishment of an osmotic gradient in renal medulla
- gradient promotes water reabsorption
distal convoluted tubule
- makes adjustments to tubular fluid composition → combination of secretion and reabsorption
collecting duct
- carries tubular fluid through the osmotic gradient in renal medulla
papillary duct
- collects tubular fluid from multiple collecting ducts and delivers to a minor calyx
Glomerular filtration rate
NET FILTRATION PRESSURE (NFP)
- glomerular hydrostatic pressure (GHP)
- glomerular colloid osmotic pressure (GCOP)
- capsular hydrostatic pressure (CHP) - generated
Regulation of glomerular filtration rate - autoregulation
- myogenic and tubuloglomerular FB sys.
regulation of glomerular filtration rate - central regulation
- RAAS & sympathetic nerve input
RAAS SYSTEM
- drop in BP & fluid vol
- liver releases angiotensinogen
- renin relase from kidney
- renin acts on angiotensinogen to form ANGIOTENSIN I
- ACE (angiotensin-converting enxyme) release from lungs
- ACE acts on angiotensin I to form ANGIOTENSIN II → also acts directly on blood vessels stimulation vasoconstriction
- angiotensin II acts on the adrenal gland to stimulate release of ALDOSTERONE
- aldosterone actso on the kidneys to stimulate reabsorption of NaCL & H2O
aldosterone
- determines potassium conc. in ECF
Oral cavity (mouth)
- ingestion
- mechanical digestion (mastication)
- propulsion (swallowing)
- secretion
pharynx
- propulsion (swallowing)
esophagus
- propulsion (swallowing)
- limited secretion
stomach
- propulsion
- chemical digestion
- mechanical digestion
- secretion
- limited absorption
small intestine
- chemical digestion
- mechanical digestion
- absorption
- secretion
- propulsion
large intestine
- absorption of water, electrolytes & vitamins
- propulsion
- limited secretion
- defecation
GI neural regulation - Sympathetic (fight or flight)
- main innervation via the thoracic and splenic nerve plexus
- effect on GIT: decreases secretion and motility, increases sphincter closure
GI meural regulation - Parasympathetic (rest and digest)
- main innervation via the vagus nerve, some input from facial, glossopharyngeal & sacral
- effects on GIT: increases secretion and motility, decreases sphincter closure
Swallowing - voluntary phase
the tongue pushes the bolus posteriorly toward the oropharynx
swallowing - pharyngeal phase
the bolus enters the oropharunx; soft palate and epiglottis seal off the nasopharynx and larynx respectively
swallowing- esophageal phase
peristaltic waves move the bolus down the esophagus to the stomach
defecation regulation: long reflex
- involves spinal cord
- parasympathetic motor fibres from the SACRAL REGION induce intensifying peristalsis in descending and sigmoidal colon and rectum; also relaxes internal sphincter
defecation regulation: short reflex
- via myenteric plexus causes muscularis to contract and internal sphincter to relax → relatively weak
catabolism
- group of reactions where one substance is broken down into smaller parts
- exergonic reactions → release energy
- cells can harness the energy relased to drive other processes
- energy released is ATP
anabolism
- group of reactions which cause smaller mulecules to be combined to make a larger molecule
- ENDERGONIC reacutions USE energy
early prophase I
chromosomes form with two sister chromatids
mid-late prophase I
during synapsis, homologous chromosomes form tetrads and CROSSING OVER occurs
metaphase I
tetrads align randomly at equator
anaphase I
random orientationin metaphase I leads to INDEPENDENT ASSORTMENT
telophase I
cytokinesis may follow, resulting in two genetically different haploid cells w/ sister chromatids still attached
prophase II
chromosomes remain condensed
metaphse II
chromosomes line up along equator
anaphase II
sister chromatids separate
telophase II
cytokinesis follows
regulation of reproductive system
- Hypothalamus: GONADOTROPIN RELEASING HORMONE (GnRH)
- Pituitary gland releases FOLLICLE STIMULATING HORMONE (FSH) & LUTEINIZING HORMONE (LH)
- stimulates ovaries and testes to produce their hormones including TESTOSTERONE, and ESTROGEN & PROGESTERONE
spermatogenesis
- spermatogonium undergoes mitosis to produce diploid primary spermatocytes
- one primary spermatocyte undergoes meiosis I to produce two haploid seconday spermatocytes
- the two secondary sparmatocytes each undergo meiosis II to produce a total of 4 haploid spermatids
- spermatids elongate as they being spermiogenesis
- spermatids continue to undergo spermiogenesis to eventually become mature sperm cells
high testosterone negative FB loop
- hypothalamus releases gonadotropin releasing hormone →stimulates the pituitary to secrete LH & FSH
- LH stimulates the Leydig cells to produce testosterone
- FSH causes cells within the seminiferous tubules to release androgen-binding protein → high conc. of testosterone near spermatogenic cells
regulation of lactation
- controlled by NEUROENDOCRINE REFLEX
- production of milk by mammary glands is a positive FB sys
- hypothalamus release PROLACTIN-RELEASING HORMONE & OXYTOCIN
- anterior pituitary responds by releasing prolactin
Oxytocin
(hypothalamus) helps release milk from mammary gkands
prolactin
(anterior pituitary) stimulates milk production
Factors regulating blood pressure - Cardiac output and blood volume
Cardiac output
- Stroke vol
- HR
Blood vol
- water loss
- water gain
