Endocrine & Nervous System Flashcards
Homeostasis
- Tendency for the body to maintain relative constant internal environment
- Dynamic process
Components of Feedback Systems
- Sensor
- Control centre
- Effector
Sensor
Body structure that detects changes
Control Centre
- Body structure that set range which variable should be maintained
- Sends signals to effector when there are changes
Effector
Body structure that responds to signal from control centre to change
Negative Feedback System
- Works to reverse change
- Thermoregulation
- Blood glucose
- BP
- pH
Positive Feedback System
- Works to increase change
- Blood clotting
- Childbirth, cramps
Nervous System uses
Electrical signals (nerves)
Endocrine System uses
Chemical signals (hormones)
Gland
Secretes specific chemical
Hormones
- Chemical made in glands that are secreted into blood
- Indirectly affect cells by initiating a series of events
Steroid Hormones
- Cholesterol
- Soluble in lipids
- Hormones binds to receptor inside nucleus to activate/inhibit gene
Protein Hormones
- Amino acid chain
- Soluble in water (insulin, GH)
- Hormones attaches to binds to cell membrane receptors to send signal for change
Hypothalamus makes & connects to
Neurohormones that move through portal veins into pituitary
Pituitary Gland, consists of
- Posterior lobe: stores ADH & oxytocin made by hypothalamus
- Anterior Lobe: makes its own hormones that are released under control of the hypothalamus
Thyroid Hormone
- Primary thyroid hormone = T4
- T4 turns into T3
- T4 finds when cells need to consume O2 & nutrients
Negative feedback loop for Thyroid
- T3 inhibits anterior pituitary
- T4 inhibits hypothalamus
Islets of Langerhans
- Endocrine cells in prancreas
- Alpha cells make glucagon
- Beta cells make insulin
Insulin works by
Decreasing lvls by makes cells put protein channels into membrane to allows glucose in through, facilitates diffusion
Glucagon works by
Increasing glucose levels
Adrenal Glands compose of
- Cortex: outer layer
- Medulla: inner layer
Adrenal medulla
- Short term stress
- Triggered by amygdala & hypothalamus
- Releases epinephrine
Adrenal cortex
- Long term stress
- Glucocorticoids, mineralocorticoids, gonadocorticoids
Coracoid hormones
- Mineralocoraticoids: increases BP
- Gondacorticoids: supplement sex hormones
- Glucocorticoids: increases sugar
Mineralocorticoids: Aldosterone
- Cholesterol hormone
- Reabsorption of Na through H2O to increas BP
Gondacorticoids
Promotes secondary sexual characteristics
Glucocorticoids: Cortisol
- Cholesterol hormone
- ACTH from pituitary gland causes release of cortisol
- Cortisol raises sugar through breakdown of muscle protein into glucose
Testes composed of
- Seminiferous tubules: sperm is made
- Interstitial cells: secretes testosterone
Androgens
Male sex hormones
Oogenesis
Making of an ovum
Ovarian Cycle
- Follicular stage: FSH stimulates follicle to mature, releasing estrogen & progesterone
- Estrogen lvls cause LH surge
- LH surge causes follicle to move through fallopian tube
Uterine Cycle
Estrogen, progesterone stimulate development of uterine lining
Corpus Luteum
- Follicle becomes this
- Makes progesterone, which allows lining to stay
Andropause
Decline in testosterone around 40 yrs
Glial Cells
Support neurons
Schwann Cells
Form myelin by wrapping around axon
Neurilemma
Outermost membrane of schwann cells, promoting regeneration of damage axons
Types of Neurons
- Sensory neurons
- Interneurons (links)
- Motor neurons
Nerve
Bundles of individual axons to form nerve fibres
Resting Membrane Potential
- Outside axon: positive, lots of Na
- Inside axon: negative, lots of K + anions
- -70mV
- Polarized
- Maintained by actively pumping
Nerve Impulses Start by
- Stimulus causing Na channels to open, flowing into cell
- Depolarizes
- Voltage gated channels open to start action potential
Action potential
- Change in charge
- -50mV
- Na flows in, K flows out
Voltage Gated Sodium Channels
- Na rushes in, raising to +40 mV
- Na channel close & K channels open from change in charge, K flows out
- Hyperpolarized, -90mV
Refractory Period
- Na-K pumps repolarizes membrane back to -70mV
- Neuron can’t fire
Nodes of Ranvier
Space btwn schwann cells
Salutatory Conduction
Conduction of impulse along myelinated neuron
Neurotransmitters are made
By neurons & stored in synaptic vesicle at the end
Releasing of neurotransmitters
- Depolarization reaches causing voltage gated Ca channels open, flowing in
- Ca causes vesicles to fuse w/cell membrane
White matter is in
- Inner region of brain areas
- Outer region of spine cord
Grey matter is in
- Outside areas of brain
- Core of spinal cord
Spinal Cord
- Link brain w/peripheral
- Primary reflex centre: coordinates incoming/coming info
Meninges
3 layers of tough, elastic tissue enclosing the brain
Blood Brain Barrier
- Glial cells & blood vessels separate blood from brain & spinal cord
- Glial cells selectively allow things to pass
Cerebrospinal Fluid
- Dense, clear liquid from plasma
- In cavities of brain, centre of spinal cord
- Move hormones, WBC, nutrients across blood brain barrier
- Shock absorber
Main regions of Brain
- Hindbrain: coordination & homeostasis
- Midbrain: processing sensory input
- Forebrain: thoughts, emotions
Cerebellum
- Lower, back part of brain
- Controls balance, coordination
- Voluntary movements
Medulla Oblongata
- Base of brain stem
- Maintains homeostasis
Hypothalamus
- Above pituitary
- Survival behaviour
Cerebrum
- Senses are sorted & interpreted
- L & R hemispheres
- Consciousness
Cerebal Cortex
- Thin layer of grey mater covering brain
- Info processing
- Memory, attention, awareness, personality, language
PNS Consists of
- Somatic
- Automatic
Somatic NS
- Voluntary control
- All myelinated
Autonomic NS
- Controls involuntary glandular secretions, smooth muscles
- Controlled by hypothalamus, medulla oblongata
Sympathetic NS
- Releases norepinephrine, epinephrine
- Increases BP, HR
Parasympathetic NS
- Restores, converse nrg
- Acetylcholine
Type 1 Diabetes
Pancreas doesn’t make insulin/not enough insulin
Type 2 Diabetes
Body is resistant to insulin
Pons
- Part of brain stem
- Connects brain to spinal cord
