INTEGRATION OF Systems

SL & HL : C3.1 ; C2.1 ; C2.2 ; D3.3

Homeostasis

maintaining a constant internal environment

emergent properties

when a group of smaller components come together to form a complex system that has features/characteristics/behaviours that the individual parts themselves do not have

hierarchy of body subsystems

cell → tissue → organ → organ system → organism

target tissue

the tissue in which the effects of a hormone take place

examples of hormones

• adrenaline (epinephrine)

nervous system

• uses electrical impulses to pass messages

• effects are quick but do not last long

• part of system controls voluntary actions + other part controls involuntary

• affects are localised, message reaching only target muscle or gland

endocrine system

• uses chemical messengers (hormones)

• transports through bloodstream

• slow results

• effects last long

• controls involuntary actions

• can reach widespread area (effects depends on receptors)

examples of receptors that relay info to the brain on a conscious level

• photoreceptors (visual info)

• chemoreceptors (changes in blood content - located outside of blood vessels)

• mechanoreceptors (sound vibrations)

• thermoreceptors (info on changes in temperature on skin)

examples of receptors that relay info to the brain on a subconscious level

• proprioreceptors (sense balance & coordination)

• osmoreceptors (sense contents of blood)

• baroreceptors (sense blood pressure - located in arc of aorta)

state the lobes + parts of the brain

1. frontal lobe

2. temporal lobe

3. brain stem

4. parietal lobe

5. occipital lobe

6. cerebellum

cerebellum function

coordinating voluntary movement, balance, posture

• also plays role in cognitive functions like language, attention, working memory

brainstem (function)

relays impulses of the cerebrum, cerebellum, spinal cord and also functions related to the autonomic central sys (ANS)

• works at a subconscious level

• medula (part of the brainstem) controls heart rate & breathing

central nervous system (CNS) consists of…

1. the brain

2. spinal cord

the peripheral nervous system (PNS) consists of…

• autonomic nervous sys (ANS)

  • sympathetic & parasympathetic NS

• somatic nervous sys (SNS)

• sensory & motor nerves

function of sensory nerves

transmits information from our body to the central nervous system

function of motor neurons

transmit information from the CNS to muscles & glands

autonomic nervous system (ANS)

• part of the PNS

the nervous system that communicates with our body tissues without our conscious knowledge

• controls breathing, heartbeat, digestion

function of the somatic nervous system

• part of the PNS

• nervous sys that communicates from the CNS to skeletal muscles, for voluntary movements

spinal cord

• a part of the central nervous system

• a thin long bundle or nerves transmitting signals from the brain to the rest of the body

sympathetic nervous system

part of the ANS that is responsible for preparing our bodies for stressful situations

parasympathetic

controls involuntary bodily functions of autonomic NS

• promotes recovery & conserving energy

system integration

the process by which different physiological systems in the body coordinate and work together

what two systems do animals use to integrate organ systems

the endocrine & nervous system

what are the two tissue types of the central nervous system

grey matter & white matter

nerve

a bundle or neurons and supportive tissues with aprotective sheath

explain (the steps of) the reflex arc

1. stimulus is perceived by receptor

2. sensory neuron transmits impulse

3. impulse reaches spinal cord

4. impulse is processed by an interneuron

5. a motor neuron is activated, stimulating a effector (muscle or gland)

note: the brain is after notified for awareness

where is the center of the endocrine system

the pituitary gland

hypothalamus

• links the nervous + endocrine system

• contains both nervous and glandular cells

circadian rhythms

• can be synchronised base don light and darkness exposure —altho will continue even with extended exposure to either

• uses melatonin (hormone) to induce tiredness

suprochiasmatic nucleus (SCN)

small region in the brain

• visible light synchronises the rhythm of the SCN when eyes sense wavelength of light they send neural impulses to SCN

• neurons in SCN triggering the production of melatonin

effects of melatonin

• effx mostly the heart, kidney & liver

• drowsiness

• reduced production of urine (kidney)

• lower core body temp

• enhanced t-helper immune response

• reduced inflammation response

• affx sexual maturation + development (thru regulation of gonadotropin)

circadian rhythms of adults vs teens

teens have a ~2h delay in melatonin release

compare nocturnal vs diurnal circadian rhythms

when melatonin is produced the physiological responses are different

• nocturnal species react to melatonin production as the motivation for activity

• whereas dirunal species react with drowsinesss

epinephrine / adrenaline

• anime hormone produced in the adrenal gland in prep for vigourous activity

• secretion is controlled by the brain

• the response to a fight or flight situation

where is the adrenal gland located

above the kidney

effects of adrenaline / epinephrine

HEART - increased heart rate - increased strength in cardiac rhythms

LIVER - break down of glycogen into glucose to provide energy for fight or flight

LUNGS - bronchioles dilate to allow more oxygen

BLADDER - detrusor muscle relaxes - internal/external sphinders contract (trapping urine inside)

VASODILATION - arterioles carrying blood to skeletal muscles dilate

VASOCONSTRICTION - arterioles carrying blood to gut, kidney, skin constrict —let less blood to flow

negative feedback mechanism

• restores the balance of homeostasis by reversing/opposing the input effects

positive feedback mechanism

• the input/effects of the stimulus are reinforced —causing more imbalance/distance from homeostasis

ex. labour/childbirth (muscle contractions)

peristalsis

the involuntary movement of food in the alimentary channel

explain the control of peristalsis

• excitatory motor neu in the smooth muscles cause the muscles behind the bolus to contract (pushing the bolus)

• inhibitory motor neurons cause the smooth muscles (infront of the bolus) to relax (allowing the bolus to pass through

ligand + how they work

a chemical that binds to another specific molecule

• their receptors can be inside or outside of a cell (depending on the molecs polarity)

• their receptors have specifcity —only a specific receptor can receive the signal of a particular ligand

• once binded the receptor changes in shape slightly, stimulating a response in the cell

examples of ligands

• hormone

• neurotransmitter

• cytokines

• calcium ions

types of hormones

• amine

• peptides & protein

• steroid

amine hormones

• small (one amino acid)

• synthesized by modified amino acids

• water soluble

• cannot pass thru membrane - receptors are on the outside of the cell

ex. epinephrine/adrenaline (from amino acid tyrosine)

peptide & protein hormones

• water soluble

• a chain of amino acids

ex. insulin (secreted by pancreas for lower glucose levels), glucagon (pancreas secreted for increases glucose lvls)

FSH & LH as glycoproteins

• secreted by anterior pituitary gland

• regulate menstrual cycle and production of egg and sperm

steroid hormones

• lipids derived from cholesterol (structurally similar)

• insoluble in water

• can pass thru membrane - receptors are inside cell

• bound to transport proteins to travel thru blood stream

ex. testosterone andoestradiol

what are the (5) chemical classes of neurotransmitters

• amine

• amino acid

• peptides

• esters

• gases

amino acid NTs

main inhibitory and excitatory messengers of nervous system

example of amino acid NTs

glutamic (excitatory)

glycine (inhib)

amine NTs

small molecules that are modified amino acids

examples of amine NTs (and function)

• dopamine

• serotonin (sleep, mood, wakefulness)

peptide NTs (neuropeptides)

made up of small chains of amino acids

• synthesized and released by neurons

example of neuropeptides + function

• endorphins (alleviate pain, improve mood, enhance sense of well-being)

ester NTs + example + function

• alcohol binded with an acid

acetylcholine (muscle contraction)

gasses NTs

• gas molecs that serve as NTs

• toxic at high concentrations

  • kept at v long doses

examples of gasses NTs + function

• nitric oxide (NO) (relaxes smooth muscles, causing vasodilation)

• carbon monoxide (CO) (reduces effects of inflammation)

• hydrogen sulfide (H₂S) (relaxes smooth muscles causes vasodilation, involved in memory formation)

Cytokines

• small signalling proteins

• intracellular communication

• bind to receptors of receiving cell’s membrane

• one cytokine can bind to multiple types of receptors

• stimulate mvment of cells to region of inflammation/infection/trauma

• help embryonic development

• help regulate cell proliferation

calcium ions (as a chemical messenger) (Ca²⁺)

• mostly within muscle fibres/neurons

• help trigger release of NTs

in muscles: attaches to proteins of sacromere triggering muscle contraction

in neurons: triggers stimulation in neurons

steps of chemical signalling

1. reception

2. transduction

3. response

reception (as the first step of chemical signaling)

• the process by which a cell detects a signal from its environment

• ligand binding to the receptor

possible responses a cell might have as a result of chemical signalling

• change in cell movement

• change in gene expression

• change in metabolism

transduction (as the second step to chem signalling)

• the process by which a change is activated within a cell —the receptor changes in structure to activate a change in the cell

response (as the third step in chemical signalling)

• change occuring inside cell as a response to stimulation

first messengers

• signalling molecules (NTs, hormones)

• extracellular factors that bind to specific receptors —depending on the molecs polarity/hydro-phobic-philic nature, its receptors are intracellular or embedded on the plasma membrane

signalling cascade

series of metabolic reactions in which one reaction triggers the next (linearly)

G-Protein-Coupled Receptors (GPCR) + structure

• group of transmembrane receptors

• found in all eukaryotic cells

• half of pharmaceutical drugs act as ligand for GPCR receptor(s)

• all have a single peptide that is folded into a globular shape

  • 7 (embedded) units

• extracellular loop parts bind with ligands

• intracellular parts of loops attach to protein complex called G-protein

  • G-protein has 3 subunits; alpha, beta, gamma

define GPCR activity (activity vs inactivity)

active: when chem signals are present

inactive: in absence of chem receptors

Formation of GPCR when inactive

• GDP (guanosine diphosphate) is bound to the alpha subunit of the G-protein complex

  • the entire G-protein complex is bound to the nearest GPCR

GPCR activation

1. ligand binds to receptors (extracellular region)

   • receptor cahnges in shape

   • GDP detaches from alpha subunit

2. GTP replaces GDP (binds to alpha subunit)

   • G-protein subunits dissociate (into GTP+alpha and beta+gamma ‘dimer’)

3. subunits can now diffuse laterally down/up membrane and interact with other membrane proteins (altho remain anchored to membrane themselves)

Guanosine Diphosphate (GDP)

nucleotide made from guanosine base, ribose sugar + 2 phosphate groups

epinephrine/adrenaline reception + tranduction + response

• binds to transmembrane receptor called adrenergic receptor (a GPCR)

1. alpha subunit activates adenylate cyclase (cell membrane enzyme)

   • adenylate cyclase catalyses conversion of ATP into cyclic AMP (cAMP, second messenger)

2. cAMP rapidly diffuses thru cytoplasm activating other molecs to spread signal of epinephrine/adrenaline in the cell

insulin reception + transduction

• binds with transmembrane receptor Tyrosine Kinase (RTK)

  • causing 2 tails of receptor to connect

  • intracellular tail is a tyrosine kinase enzyme

    • kinase phosphoralises molec by dephosphorylising ATP

• phosphorylated tyrosine causes metabolic reactions

possible responses of insulin chem signalling

1. signalling cascade that triggers movement of vesicles embedded GLUT to the PM

2. vesicles fuse with PM to facilitate glucose to pass thru PM

steroid hormone response

• binding of steroid hormones to receptors in cytoplasm or nucleus leads to change in gene expression

1. hormone receptor complex attaches to DNA at a specific gene

2. hormone-rec complex acts as transcription factor (turning on the transcription of DNA into mRNA)

3. mRNA is translated into protein at the ribosome

4. protein affects the cell

types of phytohormones (plant hormones)

• auxin

• ethylene

• cytokinin

• gibberellin

auxin (phytohormone)

regulates plant elongation

• travels to/thru phloem tissue

• produced at shoot of plant

• can easily enter cells of plant but cannot exit

auxin molecules more to opposite direction of light absorbtion to allow for the tissue of the opposing side to elongate — bending the plant in the direction of the light source/optimal light absorbtion

how does auxin promote plan cell elongation

1. auxin promotes synthesis of H+ ion pump

2. H+ is pumped into apoplast

3. H+ activates protein expansin (part of cell well)

4. expansin looses the H bonds within cell wall + cross linked cellulose fibres (weakening the cell wall)

5. as water is absorbed turgor pressure is established (the cell memb presses against cell wall)

6. due to weakness in cell wall, it is stretched

7. fibres of cellulose then create new H bonds

Cytokinin (phytohormone) function

increases rate of cell division

• produced in the root

gibberellin (phytohormone) function

• control of stem elongation

• seed germination

• flowering

• dormancy

ethylene (phytohormone)

responsible for fruit rippening

• example of positive feedback

• can be passed between fruits

types of neurons

• sensory

• motor

• relay

structure of neuron

dendrites (function)

• receive signal from other neurons

• relay signals to soma

soma (function)

• contains nucleus

• processes incoming signal

• generates outgoing signal

axon (function)

transmits electrical impulses (action potential) from cell body to other neurons, muscles, glands

myelin sheath

• fatty insulative layer

• formed by schwann cells (in PNS) and oligodendrocytes (in CNS)

speeds up transmission of signal thru axon

resting potential

stable, negative electrical charge under cell membrane maintained by neuron when not actively transmitting a signal

polarised neurons

neuron at resting potential (w a negative charge inside cell in comparison to outside, as a result of ion distribution imbalance)

how do sodium-potassium pumps lead to resting potential

the pump allows for 3 Na+ to exit the cell, but only 2 K+, a net charge of -1 inside of the cell

• actively transported

however there is a potassium leak channel that allows for K+ to exit the cell freely depending on the gradient

action potential

rapid temporary change in a neuron’s membrane potential, where it shifts from -ve → +ve → -ve, allowing the signal to travel along the neuron

depolarisation

process during an action potential where Na+ ions move into neuron, making the memb potential ⬇ negative (aka closer to positive)

repolarisation

a phase after that occurs immediately after depolarisation where the K+ ions exit the neuron, returning the membrane’s potential back to -ve resting state

saltatory conduction

impulses “jump” from one node of ranvier to the next, allowing for the signal to be transmitted faster

• it is energy efficient as less energy is used to allow the sodium-potassium ion pump to letting the K+ and Na+ ions to move in and out of the cell

transfer of signal between neurons

1. action potential travels down to axon terminal

2. depolarisation opens voltage-gated calcium channels (Ca2+ can enter terminal)

3. the increase in Ca2+ conc inside cell triggers synaptic vesicles with NTs inside to move towards presynaptic membrane

4. NTs are released into synaptic cleft by exocytosis

5. Nts diffuse across synaptic cleft binding to receptors of post-synaptic neuron (opening sodium channel)

6. sodium ion enter cell (depolarisation), if the depolarisation reaches threshold potential, a new act pot is generated

   • NTs are degraded by enzymes or take back to presynaptic neuron for re-uptake (ending signal transmission)