The Brain
2 Main Parts: Cerebrum (conscious) The rest of the brain (unconscious)
(a) Unconscious Brain 1.Medulla Oblongata (Brain stem)… #8 Heartbeat Respiration rate Blood pressure regulation Vomiting, coughing, etc
2. Hypothalamus… #13 Associated with homeostasis Hunger/thirst Sleep Body temperature Blood pressure Pituitary gland
3. Thalamus… #5 Relay between spinal cord and brain using the Reticular Activating System (RAS) Screen sensory impulses
4. Cerebellum… #7 Muscle coordination and balance (inner ear)
Cerebrum Basics
(b) Conscious Brain (Cerebrum) Right and left hemispheres 4 surface lobes on each side Let’s take a look at each lobe…
**Label the lobes on both diagrams, if possible! 1. Frontal Lobe…#1 Intellect Voluntary muscles (skeletal) 2. Parietal Lobe…#4 Sensory (from skin) 3. Temporal Hearing, smelling, speech 4. Occipital…#6 Vision
Left and right hemispheres connected by the CORPUS CALLOSUM… #2
Neurotransmitters Chemicals that communicate info through the brain and body Relay signals between neurons Control everything from your heart beat to digestion!
Excitatory Neurotransmitters Initiate impulses in adjacent neurons Examples: acetylcholine, norepinephrine, epinephrine, dopamine *They get the neurons firing! (Depolarization sequence)
Inhibitory Neurotransmitters These inhibit the firing of impulses Can help stop responses such as tremors and seizures Examples: Serotonin, GABA A balance of inhibitory and excitatory neurotransmitters in needed for proper brain function!
Drug Interactions Nicotine Shaped like acetylcholine (neurotransmitter) Binds to receptors, increasing action potentials Increases dopamine release - Stimulate muscle movement, breathing, heart rate, learning, and memory
Alcohol Mimics GABA's effect by binding to GABA receptors Acts as an inhibitor Simulates endorphins (like GABA and serotonin) as a naturally produced pain killer
Marijuana Chemical produced called THC Binds to cannabinoid receptors Affects cerebellum (coordination), cerebral cortex (concentration, perception) and hippocampus (memory, learning)
Cocaine Acts by blocking dopamine transporters (clear dopamine out of the synapse) Dopamine builds up in synapse Amplified signal to neurons = feelings of euphoria
Fentanyl Similar to morphine but 50-100x more powerful Belong to Opioid group of drugs (painkillers) Increases dopamine levels Dangerous forms are being synthesized in labs many overdose deaths Deaths associated with respiratory distress
Neuroendocrine Control (Hormones) Epinephrin (Adrenaline) Source: Adrenal medulla (central portion of adrenal gland) Effects: “fight or flight” response Increased heart rate Increased [glucose] in blood Decreased blood flow to digestive tract & skin Increased breathing rate Increased circulation to voluntary muscles
Control: Secretion of adrenalin by adrenal medulla controlled by hypothalamus Signal travels via brain stem spinal cord sympathetic nerve fibers adrenal medulla
2. The Pituitary Gland… #12 *Controlled by the HYPOTHALAMUS
Posterior Pituitary Hormones: ADH, Oxytocin ADH- results in kidneys retaining water Oxytocin- causes contraction of the uterus (childbirth) & milk production at mammary glands
(b) Anterior Pituitary Hormones: GH- growth hormones (whole body) FSH & LH- teste/ovary development LTH (lactogenic hormone)- develops mammary glands TSH (thyroid stimulating hormone) ACTH- stimulates adrenal gland
Negative Feedback Loops Sensor Organ Response Homeostasis Stimulus (internal or external)
Example: ADH Release Stimulus: [water] decreases in blood low blood volume Sensor: Hypothalamus Organ: Pituitary gland (posterior) Response: Release ADH effects collecting duct of nephron (in kidneys) Homeostasis: Retain water blood volume increases *Once blood [water] increases, pathway is shut down = self regulatory!!