WACE - human bio

action of steroid hormone

lipid-soluble, diffuse directly through membrane and attach to receptor inside cell (nuclues/cytoplasm) and creates hormone-receptor complex and binds to a section of DNA causing changes in gene expression;protein synthesis. they are slow but long-lasting

action of protein/amine hormone

water-soluble, cannot diffuse directly and attaches to receptor on membrane creating a hormone-receptor complex causing release of a secondary messenger in cell triggering enzyme activity and change cells functioning. It is fast but short-lasting and reversible

thyroxine

target cell: all body cellsfunction: increase metabolism and heat to have control of body temperature

oxytocin

target organ; uterus and mammary glandsFunction: contraction of uterine muscles during childbirth and release of breastmilk

Calcitonin

target organ: kidneys and bonesfunction: decrease levels of calcium in blood by decreasing rate of calcium absorption by kidney and rate of bone breakdown

Parathyroid

target organ: bonesFunction: increase levels of calcium in blood by increasing rate of absorption by kidney and bone breakdown

antiduretic hormone

target cell: kidneyfunction: increase water reabsorption by increasing permeability of DCT and CT into blood

Insulin

target cell: cells/bloodfunction: decrease blood sugar levels

Glucagon

target cells: cell/bloodfunction: increase blood sugar levels

testosterone and oestrogen

target organ: most tissuesfunction: testosterone - secondary sex characteristics /production of sperm and oestrogen - secondary sex characteristics/regulation of menstrual cycle

Luetinising hormone

target organ: ovaries and testesfunction: ovaries - ovulation and maintenance of corpus luteum and testes - release and production of testosterone

follicle stimulating hormone

target organ: ovaries and testesfunction: ovaries - stimulate release of follicle and growth and testes - stimulate and release production of sperm

growth hormone

target cells: all cellsfunction: growth of cells and rate of protein synthesis

thyroid stimulating hormone

target organ: thyroid glandfunction: release of hormones from thyroid gland

cortisol

target organ: most cellsfunction: regulate blood sugar level and promote metabolism/stress hormone

aldesterone

target organ: kidneyfunction: sodium reabsorption and water reabsorption

adrenaline and noradrenaline

target organ: most cellsfunction: fight/flight response

prolactin

target organ: mammary glandsfunction: production of breastmilk

adrenocorticotropic hormone

target organ: adrenal cortexfunction: release of hormones from adrenal cortex

thymosin

target organ: T cellsfunction: development/maturation of T cells

what is the main role of the endocrine system

to maintain homeostasis by secreting hormones that regulate body functions. E.g. metabolism and water balance

how do hormones differ from nerve impulses

hormones are chemical and travel through bloodstream, they are slower but longer lasting whereas nerve impulses are electrical and travel through nerve fibres they are faster but short-lasting

why do hormones only affect specific target cells

the target cells have receptors that are specific to the hormones shape

what is the difference between endocrine glands and exocrine glands

endocrine glands are ductless and secrete into extracellular fluid (bloodstream) whereas exocrine glands contain ducts and secrete into lining of epithelial tissue

what connects hypothalamus to pituitary gland

infundibulum

how does the hypothalamus control the anterior pituitary

through a network of blood capillaries in hpps which goes through infundibulum and hypothalamus sends releasing and inhibiting factors which stimulate/inhibit production of hormones

what is the function of the hpps

it is responsible for being a network of blood capillaries that carries hormones from hypothalamus to anterior pituitary

how does the hypothalamus control the posterior pituitary

through nerve impulses that travel down neuron to release hormones producd in hypothalamus that are stored in posterior pituitary to be released into bloodstream, when nerve impulse arrives the hormones are released from posterior lobe into bloodstream

why is hypothalamus the link between nervous and endocrine system

it recieves nerve signals and sends hormonal signals to control bodily functions

what is the difference between steroid and protein/amine hormones

steroid hormones are lipid-soluble and able to diffuse through cell membrane directly, attach to receptor inside cell and is slow but longer-lasting whereas protein/amine hormones are water-soluble and cannot diffuse directly through cell membrane and attach to receptor on membrane and is fast but short-lasting and easily reversible

what is steroid hormones effect on cells

diffuse through cell membrane and attach to receptor in cell cause hormone-receptor complex and binds to region of dna causing a change in gene expression and rate of protein synthesis to make new proteins

what is protein/amine hormones effect on cells

attach to receptor on membrane and form hormone-receptor complex releasing secondary messenger causing a change in enzyme activity

what type of feedback controls most hormone secretions

negative feedback

effect of glucagon and insulin on blood sugar levels

insulin - decreases blood sugar levels through increasing glucose uptake
glucagon - increase blood sugar levels through glucose being released from liver

effect of adh on water balance

adh increases water reabsorption of kidney by increasing permeability of DCT and CT to prevent dehydration

effect of thyroxine on temperature regulation

it increases metabolic rate to generate heat and control body temperature

effect of cortisol on body during stress

it raises blood glucose and energy levels in body to help cope with long-term stress

effect of parathyroid hormone

increases calcium levels in blood by increasing absorption by kidney and rate of bone breakdown

what is synthetic hormone

it is a man-made hormone that chemically mimicks effects of natural hormone

what is recombinant dna

it is a hormone produced using recombinant DNA techonology, human genes inserted into bacteria to produce a hormone

example of recombinant dna

recombinant insulin - diabetes

example of synthetic hormone

levothyroxine - hypothyroidism

advantage of recombinant hormones

they are identical to human hormones and do not cause allergic reactions

which system acts faster

nervous

which system lasts longer

endocrine

how are messages transmitted in each system

nervous - nerve impulses via neuron
endocrine - hormones via bloodstream

similarity of nervous and endocrine system

both work together to coordinate body functions and maintain homeostasis

which part of body links the two systems

hypothalamus

why would damage to pituitary gland affect multiple systems

as it releases tropic hormones which controls other endocrine glands and hormones it releases

how does negative feedback work to maintain stable levels

when hormones effect restores balance it slows production to prevent overcorrection

how does stress involve both nervous and endocrine systems

nervous system triggers release of adrenaline, endocrine system releases cortisol for a longer-term response

what would happen if insulin wasn’t produced properly

blood glucose levels would continue to rise leading to diabetes

what is the main role of the nervous system

to detect stimuli, process information and coordinate rapid responses through effectors to maintain homeostasis

what are the three main functions of the nervous

sensory input, integration and motor output

what are the two main divisions of the nervous system

peripheral nervous system and central nervous system

what does the nervous system include and do

brain and spinal cord; process information and coordinate responses

what does the peripheral nervous system include and do

cranial and spinal nerves; transmits messages between CNS and body

what are the two functional divisions of the PNS

somatic nervous system and autonomic nervous system

what does the somatic nervous system control

voluntary movement of skeletal muscles

what does the autonomic nervous system control

involuntary actions of smooth and cardiac muscle and glands

how many neurons involved in somatic motor pathway

one neuron from cns to effector

how many neurons are involved in autonomic motor pathway

two neurons - preganglionic and postganglionic with a ganglion in between

what neurotransmitters are used in somatic nervous system

acetylcholine

what neurotransmitters are used in autonomic nervous system

acetylcholine and noradrenaline

what is the main function of sympathetic nervous system

prepares the body for fight/flight responses during stress/activity

what is the main function of the parasympathetic nervous system

promotes the body for rest/digest functions, calming body after stress

what are two effects of sympathetic nervous system

increases heart rate, dilates pupils

what are two effects of parasympathetic nervous system

decreases heart rate, constricts pupils

what is a neuron

a specialised nerve cell that carries impulses throughout the body

what is the function of dendrites

recieving incoming signals and sending them to cell body

what is the function of the axon

transmits impulses away from cell body to other neurons/effectors

what does myelin sheath do

it insulates the axon and acts as a protective barrier that stops interference of nerve impulse transmission and speeds up transmission

what are the nodes of ranvier

gaps between myelin sheath, where impulses jump speeding up transmission

what maintains the resting membrane potential in a neuron

sodium potassium pump

what happens during depolarisation

sodium voltage gated channels open and sodium enters cell making it more positive

what happens during repolarisation

potassium channels, open and potassium leaves cell and inside becomes negative again

what is the all or nothing response

a neuron fires completely or not at all once threshold is reached

what is salutory conduction

an impulse jumps between nodes of ranvier in a myelinated axon for faster transmission

what happens when an impulse reaches the axon terminal

calcium channels open and neurotransmitters released into synapse

how do neurotransmitters trigger the next neuron

they bind to receptors on post-synaptic membrane, opening sodium channels

what stops contious stimulation at a synapse

enzymes break down neurotransmitters or are reabsorbed by reuptake

what is a reflex

a fast, automatic and involuntary response to a stimulus

what is the pathway of a reflex arc

stimulus, receptor, sensory neuron, interneuron, motor neuron, effector and response

why are reflexes fast

they are processed in the spinal cord not the brain

what is integration

the cns processes and interprets sensory input and deciedes on a response

what is coordination

pns carries message from cns to effectors to carry out responses

how does nervous system maintain homeostasis

by detecting changes, processing them in CNS, and sending signals to effectors to restore balance

what type of feedback controls homeostasis

negative feedback

give an example of nervous control in homeostasis

thermoregulation - hypothalamus detects temperature change, signals sweat glands and blood vessels to respond by producing sweat and dilating vessels

what is thermoregulation

the maintenance of a stable body temperature ($\sim37’C$) through negative feedback

what detects temperature changes in the body

central and peripheral (hot/cold) thermoceptors in the skin and hypothalamus

what part of the brain acts as the modulator in thermoregulation

hypothalamus

what effectors cool the body when temperature rises

sweat glands and blood vessels

what effectors help to warm the body when temperature falls

skeletal muscles and blood vessels
long-term = increased thyroxine production

is thermoregulation controlled by nervous or endocrine system

it is controlled by both systems; nervous is for fast and rapid responses in short-term and endocrine is for slow and long term responses such as thyroxine production

what is the normal blood glucose level range

4-6mmol/L

which organ detects changes in blood glucose levels

pancreas - islets of langerhans

what hormone lowers blood sugar levels

insulin released from beta cells

what hormone raises blood sugar levels

glucagon released from alpha cells

how does insulin lower blood glucose levels

through promoting uptake of glucose in cells, and forming glycogen in liver - glycogenesis