exam 4 laforge

what is function of cell body (soma)?

• Contains nucleus

• Controls neuron activities

• Performs metabolism and protein synthesis

what do dendrites do?

• Receive incoming signals

• Carry signals toward the cell body

whats an axon?

• Long extension that carries signals away from the cell body

• Sends signals to other neurons

what is myelin sheath?

• Fatty coating around the axon

• Insulates axon

• Speeds up impulse conduction

what are nodes of ranvier

• gaps in myelin

• faster signal jumping saltatory conduction

what is axon terminal?

• End of the axon

• Releases neurotransmitters

• Communicates with the next neuron

whats a synapse?

• Space between neurons

• Where neurotransmitters cross

• Site of neuron-to-neuron communication

what are neurotransmitters?

• Chemical messengers

• Travel across synapse

• Bind to receptors on next neuron

astrocytes

• Remove extra neurotransmitters

• Maintain chemical balance

• Form blood–brain barrier

microglia

• Immune cells of the nervous system

• Destroy germs + clean up debris

oligodendrocytes

• Make myelin in the CNS

• Insulate multiple axons

• Speed up signals

schwann cells

• Make myelin in the PNS

• Help nerves regenerate

• Insulate one axon at a time

ependymal cells

• Line brain ventricles

• Produce and circulate CSF

satellite cells

• Surround neuron cell bodies in the PNS

• Provide support + regulate environment

glial cells

• neuron helpers

• doesnt send signals

What is the sympathetic nervous system?

• “Fight or flight”

What is the parasympathetic nervous system?

• “Rest and digest”

Main difference between sympathetic & parasympathetic?

• Sympathetic = activates body

• Parasympathetic = calms body

• Opposite effects

What neurotransmitter does parasympathetic use?

Acetylcholine (ACh)

What neurotransmitters does sympathetic use?

• Epinephrine (adrenaline)

When is sympathetic active?

• Stress

• Danger

• Exercise

• Emergencies

When is parasympathetic active?

• Eating

• Relaxing

• Sleeping

• Calm moments

sympathetic body interactions

• increases heart rate

• slows digestion

• dilates pupils

parasympathetic body interactions

• decreases heart rate

• stimulates digestion

• constricts pupils

What does Thyroid-Stimulating Hormone (TSH) do?

• Stimulates: Thyroid gland

• Reaction: calcitonin → boosts metabolism

What does Adrenocorticotropic Hormone (ACTH) do?

• Stimulates: Adrenal cortex

• Reaction: Releases cortisol → increases stress response & blood sugar

What does Growth Hormone (GH) do?

• Stimulates: Bones & muscles

• Reaction: Growth, protein synthesis, cell division

What does Follicle-Stimulating Hormone (FSH) do?

• Stimulates:

  • Ovaries → egg/follicle development

  • Testes → sperm production

• Reaction: Prepares egg; makes sperm

What does Luteinizing Hormone (LH) do?

• Stimulates:

  • Ovaries → ovulation

  • Testes → testosterone release

• Reaction: Egg release; increases testosterone

What does Prolactin do?

• Stimulates: Mammary glands

• Reaction: Produces milk

What does Antidiuretic Hormone (ADH) do?

• Stimulates: Kidneys

• Reaction: Saves water → reduces urine output

What does Oxytocin do?

• stimulate uterine smooth muscle

  • labor and delivery

3 diff hormone interaction

synergistic, permissive, antagonist effect

synergistic effect

• Two hormones work together

• Combined effect is stronger than either alone

permissive effect

One hormone enables another to work

antagonist effect

• One hormone opposes another

• Example: Insulin lowers blood sugar; Glucagon raises it

What are lipid (steroid) hormones?

• made from cholesterol

• Fat-soluble → cross cell membranes

• Examples: Cortisol, Testosterone, Estrogen

• Bind inside cells → change gene activity

What are protein (peptide) hormones?

• Water-soluble → cannot cross membranes

• Bind cell surface receptors → use second messengers

How do protein hormones affect the brain?

• Usually cannot cross blood–brain barrier

• Act indirectly via receptors on blood vessels or brain regions

Examples of lipid (steroid) hormones

Cats Take Every Piece Alone

• C = Cortisol

• T = Testosterone

• E = Estrogen

• P = Progesterone

• A = Aldosterone

Examples of protein (peptide) hormones

I Got Hungry Please Order

• I = Insulin

• G = Glucagon

• H = Growth Hormone (GH)

• P = Parathyroid Hormone (PTH)

• O = Oxytocin

Testosterone (lipid hormone) effects

• Male: sperm production, muscle growth, deep voice

• Female: small amounts → libido, bone health

Estrogen & Progesterone (lipid hormones) effects

• Female: menstrual cycle, breast development, fertility

What is Multiple Sclerosis (MS)?

• Immune system attacks myelin sheath of neurons

• Slows or blocks nerve signals

• exposes nerve fibers

neuroglial cells in CNS

Mnemonic: “All Mighty Owls Eat”

• A = Astrocytes

• M = Microglia

• O = Oligodendrocytes

• E = Ependymal

neuroglial cells in PNS (peripheral)

Mnemonic: “Super Stars”

• S = Schwann cells

• S = Satellite cells

action potential

• Electrical signal traveling along a neuron

• Allows neurons to communicate

sodium goes on

depolarization

potassium goes on

repolarization

resting potential

• Neuron at rest → ~-70 mV

• Inside cell: more K⁺, negative charge

• Outside cell: more Na⁺, positive cha

depolarization

• Na⁺ channels open → Na⁺ rushes in

• Inside becomes more positive

• Starts the action potential

• +30 mV

repolarization

• K⁺ channels open → K⁺ leaves cell

• Inside returns to negative

• Restores resting potential

hyperpolarization

• K⁺ channels stay open a bit longer

• Membrane becomes slightly more negative than resting

• -75 mV

Sodium-Potassium Pump (Na⁺/K⁺ pump)

• Pumps 3 Na⁺ out and 2 K⁺ in

• Maintains resting potential

• Uses ATP

threshold voltage

-55 mV

• reach threshold: Na⁺ channels open → depolarization starts

direct hormone secretion

• Gland releases hormone straight into the blood

• No intermediate signal

indirect hormone secretion

• Gland releases hormone in response to another hormone

• Often involves tropic hormones

gap junction

• Direct cytoplasmic connection between cells

• Allow ions and small molecules to pass instantly

endocrine system

• A system of glands that release hormones

major endocrine glands

• Pituitary

• Thyroid

• Parathyroid

• Adrenal

• Pineal

• Pancreas

• Ovaries (female) / Testes (male)

what two systems make up internal communication

nervous and endocrine

what type of signals does nervous system use?

electrical and chemical (neurotransmitter)

how does endocrine communicate

using hormones secreted into circulation

endocrine system functions (5)

• coordinates intercellular communication

• homeostasis

• growth & development

• water retention

• reproduction

hormones

chemical messengers

hormones communicate in 2 ways

direct and indirect secretion

exocrine glands

release excretion through ducts

• ex: sweat glands

endocrine glands

release secretions into body

type 1 diabetes

pancreas fails to produce insulin

type 2 diabetes

body insulin resistant

a mutant cell glucose gates stay closed because

insulin receptor was never injected into the cell membrane

anterior pituitary gland

protein hormone production

what controls pituitary gland

hypothalamus

3 step feedback loop - nervous system

1. sense organ gets message

2. CNS processes & reacts to message

3. CNS commands sense organ to react

CNS contains?

brain and spinal cord

PNS (peripheral)

all neurons and ganglia outside of CNS

• sensory and motor neurons

sensory neurons (PNS)

touch, temp, light, chemical taste/smell, and pain

motor neurons

visceral and somatic

somatic

conscious activity

visceral

parasympathetic and sympathetic

para and sympathetic nervous system makes?

autonomic division of peripheral nervous system

neuron properties

excitability, conductivity, secretion

excitablility

responds to stimuli (environmental change)

conductivity

spread response of stimuli to other distant cells

secretion

able to secrete neuro-transmitters to communicate nerve to nerve

sensory (afferent)

detect and transmit

interneurons

• connect sensory and motor neurons

• process and integrate info

motor (efferent) neurons

receive and react

neuroglia

• support neuron functions

• protects and gives directionality

• 6 types

grey matter

• soma of neurons are clustered

• grey bc tightly condensed organelles

• where we process info

white matter

• high concentration of axons

• have myelin which is white fat

forebrain

lateral hemisphere

• conscious thought

• behavorial reflex: emotion

• voluntary motor control

midbrain

• on top of hind brain

• low reflex, react to noises, knee reflex

hindbrain

• connects to spinal cord

• vegetative function : breathing, heart rate, vomit, cardiovascular

Cerebral Spinal Fluid (CSF)

renews the internal environment of brain

meninges

tissue between cns and boney covering

meninges layers

dura mater, arachnoid mater, pia mater

sympathetic neurotransmitter

adrenaline

adrenaline effects

• up cardiac rate

• vasoconstriction

• dilate airways/pupils

sense organs

smell, taste, vision, hearing, equilibrium

• in complex organs