Autonomic and Endocrine Systems Flashcards
Organisation of nervous system
-sensory (afferent) neurons transfer information from the PNS to the CNS
-motor (efferent) neurons transfer information from the CNS to the muscle and glands
-motor neurons can be divided into somatic and autonomic neurons where somatic means voluntary and autonomic means involuntary
-autonomic motor neurons can then be divided into sympathetic and parasympathetic motor neurons, and these alter how your body is functioning
Alarm response (sympathetic division)
Heart
-increase heart rate and contraction force - pump more blood around body
Eyes
-dilate pupils - more aware of surroundings (increased sensory awareness)
Mouth
-decreases saliva - changing energy balance in body to deal with immediate threat rather than using energy for digestion
Lungs
-dilate bronchi and breath faster - oxygen in and carbon dioxide out more quickly, faster breathing
Skin:
-constrict peripheral blood vessels - stops blood flowing fast into extremities but keeping blood flowing into muscles and places that need it
-contract arrector pili muscles - little hairs on skin → hairs stand up
-increase sweat secretion - gets rid of heat
Gut:
-decrease digestion - changing energy balance in body to deal with immediate threat rather than using energy for digestion
-increase blood sugar - more glucose for ATP production
-increase blood pressure and water retention - kidneys change water retention balance because we want to make sure we can keep our blood pressure high to feed our muscles and internal organs in case we are getting damaged or to allow us to get away from things
Relaxation response (parasympathetic division)
Heart
-decrease heart rate and contraction force
Eyes
-contract pupils
Mouth
-increase saliva
Lungs
-constrict bronchi, breath more slowly
Skin
-dilate peripheral blood vessels - more blood to periphery, warmer on surfaces
Gut
-increase digestion
Autonomic vs somatic motor neurons
-autonomic neurons control the body’s internal responses to allow us to adapt to change all the time
-autonomic nervous system effects smooth muscle, cardiac muscle and glands and is involuntary with internal sensory input
-the somatic motor neuron is myelinated and uses acetylcholine as its neurotransmitter
-the autonomic nervous system uses a myelinated pre ganglionic neuron and a unmyelinated post ganglionic neuron and uses two neurotransmitters: acetylcholine and norepinephrine, it first sends a signal to the ganglion which sends a signal to many other places at once
Autonomic motor neuron nerve synapses
Sympathetic division
-acetylcholine is generally neuron used by preganglionic neuron and ganglion
-postganglionic neuron to effector cells that are not sweat glands use norepinephrine
-for sweat glands acetylcholine is used for the second synapse
Parasympathetic division
-acetylcholine is only neurotransmitter used
Raynaud Disease
-sympathetic system gets turned on and does not get turned off as quickly as it is supposed too, results in excessive stimulation of sympathetic system following emotional stress or exposure to cold
-chronic vasoconstriction → fingers and toes become ischemic (lack of blood) and appear white
Endocrine System organs and starting points
-hypothalamus and pituitary gland are starting points for many endocrine organs
-hypothalamus controls internal organs via: autonomic nervous system and pituitary gland
-hypothalamus regulates: behaviour patterns, circadian rhythm, body temperature, eating and drinking
-endocrine organs secrete hormones into bloodstream
-hypothalamus, pituitary gland and adrenal glands are the foundation of endocrine system
-endocrine organs include the pineal gland, skin, liver, small intestine, pancreas, thyroid, thymus, heart, stomach, kidney, ovary, testes
Hormone types and control of hormone release
-endocrine hormones are released into bloodstream, circulate and exit blood system to affect tissues in other parts of the body
-paracrine hormones means nearby
-autocrine hormones affect own behaviour
Control of hormone release
-synthesis, storage release → circulation in blood → desired response (target cell with receptors) → hormone disposal and usually negative feedback signal for synthesis of hormone
Lipid soluble hormones
-circulate through blood via transport protein, lipid soluble hormone can then diffuse straight into cell (hydrophobic so can pass through plasma membrane)
-activated receptor-hormone complex can alter gene expression and newly formed mRNA directs synthesis of specific proteins on ribosomes
-if cell has nuclear receptors, gene expression can be altered
-only affects cells that have the nuclear receptors in the cell
Water soluble hormones
Water soluble hormones
-do not need carrier protein as they are soluble in plasma, but cannot get through plasma membrane so the cell has to have a receptor on its surface for it (transmembrane complexes linked to internal structure - G protein and adenylyl cyclase)
-when hormone binds to receptor, G protein structure alters activating enzyme, enzyme converts ATP to cAMP (internal messenger)
-cAMP affects a number of other enzymes (protein kinases)
-phosphorylated enzymes (from protein kinase phosphorylation) catalyse reactions that produce physiological responses
-phosphodiesterases - deactivate cAMP - cause the process to only work when the hormone is bound to the receptor
Cholera
-bacterium that infects gut, produces cholera toxin that binds to G proteins on transporters on gut epithelium locking them in an activated state
-leads to high cAMP levels internally, causes them to pump Cl- into intestines
-water follows out, chronic diarrhoea
Hypothalamus and pituitary gland
-hypothalamus is a number of nuclei sitting in base of brain, controls endocrine system by influencing pituitary gland
-two lobes of pituitary gland (anterior and posterior lobe)
-stalk connects the lobes to brain called infundibulum
-network of capillaries around base of hypothalamus and over anterior and posterior pituitary gland
-pituitary being fed by capillaries that have come from another capillary network over the hypothalamus called hypophyseal portal veins - veins connect a capillary bed to another capillary bed - portal system
-reason for portal system is that it allows hypothalamus to communicate with anterior pituitary using hormones
-hypothalamus controls endocrine system using hormones it can release through the capillary network through the portal system to affect the pituitary gland
-9 hormones (releasing and inhibiting hormones to control pituitary gland) produced by hypothalamus
-pituitary gland produces 7 hormones (controlling endocrine organs)
-together regulate growth, development, metabolism, homeostasis
Adrenal glands
-sit on top of the kidneys
-organ has capsule around to keep its integrity, outer layer called cortex
-different cells in inner section called medulla → different cells and functions
-medulla and cortex do different things in endocrine functions
The adrenal medulla
-sympathetic nervous system has preganglionic neurons coming from spinal cord that terminate in the adrenal medulla
-they synapse with cells in the adrenal medulla not postsynaptic neurons
-when those cells are triggered in the medulla they release two hormones into the bloodstream: norepinephrine and epinephrine
-modified postganglionic ‘neurons’ acting as secretory cells
-extending the sympathetic alarm response
-stimulated by: acetylcholine (neurotransmitter) from preganglionic neurons
-hormones released: epinephrine (adrenaline) and norepinephrine
-principal actions: enhance sympathetic autonomic alarm response
Adrenal cortex hormones
Hormones A:
-mineralocorticoids (e.g. aldosterone) - hormones that affect the balance of metal ions in the body, stimulated by increased K+ and angiotensin II in blood (hormone),
-principal actions: increase Na+ and water and decrease K+ in blood to increase blood volume and pressure
Hormones B:
-glucocorticoids (e.g. cortisol) - stimulated by ACTH (adrenocorticotropic hormone) from pituitary gland (corticotropin releasing hormone (CRH) from hypothalamus)
-principal actions: resistance reaction to stress, control (dampen) inflammation, alters balance of different types of immune responses we can generate - so that immune system do not get out of control or use too much energy at a time we may need it in dealing with the danger with our sympathetic alarm activation
-CRH from hypothalamus to pituitary gland, ACTH from pituitary to adrenal gland
Actions of cortisol and Negative feedback control
-high concentrations of cortisol down regulates production of ACTH (turns of signal with negative feedback)
-high concentrations of cortisol effects hypothalamus by inhibiting release of CRH
The stress response
First stage: alarm response
-immediate burst
-sympathetic autonomic activation: mobilise resources for immediate physical activity, increases production of glucose and oxygen, activates sensory system for alertness and activity, so that we can ward off danger or flee
-sustained through action of adrenal medulla
Second stage: resistance reaction - reduce tissue damage (adrenal cortex)
-also an inducible system
-slower, longer lasting
-associated with hypothalamus, pituitary and adrenal cortex, effects are of cortisol
