The Hindbrain, Midbrain, Forebrain.

brain

Corpus Callosum

Connects the two hemispheres of the brain, allows halves to communicate.

Brain and Spinal cord are protectd by what?

Bone (skull/vertebrae), Meninges (layers of tissue surrounding organ, Dura Arachnoid Pia), Cerebrospinal fluid (Fluid between meninges and organ, clear and odorless.)

Difference of meninges between brain and spinal cord.

Brain - no epidural space, 2 layers of dura (inner layer is continuous w/ SC dura)

How does Cerebrospinal fluid protect the brain and spinal cord?

Acts as a shock absorber, continuously circulates around the brain, helps with buoyancy and chemical stability.

Buoyancy and Chemical Stability in relation to CSF.

Buoyancy - CSF has similar density to brain, allows it to be suspended within the skull, no pressure on the bottom of the brain. Chemical Stability - Removes waste from CNS.

Ventricles

4 Chambers/Canals in the brain filled with CSF. CSF is made by neuroglial cells, many of which are found lining the ventricles.

Blood Brain Barrier

Regulates what substances get from blood to brain.

Blood Brain Barrier, what is it highly permeable to?

Highly permeable to: Oxygen, Glucose, Water, Carbon Dioxide, Caffeine, Alcohol, Nicotine.

Blood Brain Barrier, what are some obstacles for delivering?

Medications to treat blood diseases, when there is trauma and inflammation, can cause damage to BB and pathogens can get it.

Medulla Oblongata

In Hindbrain, tracts carry motor signals from cerebrum to spinal cord (stims skeletal muscles) nerve fibers decussate, receive input from taste buds, pharynx, and organs of abdominal and thoracic cavities. Motor control primitive body functions heart rate, breathing, blood vessel diameter.

Pons

Hindbrain, “bridge”, conducts signals from cerebrum to the cerebellum and medulla. Concerned with: Sleep, Hearing, Equilibrium, Taste, Eye Movements, Respiration, Swallowing, Bladder Control, Posture.

Cerebellum

Hindbrain, right and left hemispheres, connected by vermis. Muscular Coordination and balance, passage of time, judgement, memory (reflex/muscle) emotion. Only 10% of brain, has 50% of body nerve cells.

Purkinje Cells

Largest neuron in brain with a complete complex dendrite structure.

Ataxia

Damage to cerebellum, causes balance issue and wider stance/gait.

Mid Brain

Section of brain stem - Acts as connector for hindbrain and forebrain.

3 Parts of Midbrain

Tectum (colliculi), Tegmentum, Cerebral Peduncles.

What is the midbrain associated with?

Vision and Hearing, Motor Control, Sleep and Wakefulness, Alertness, Temperature Regulation.

Tegmentum

Fibers connect to cerebellum, involved in fine motor control, main mass of midbrain. IN MIDBRAIN.

Tectum

IN MIDBRAIN. 2 superior colliculi (visual attention, tracking objects in our line of sight) triggers reflex-like action to turn head and look. 2 Inferior Colliculi - info from inner ear, triggers you to turn head.

Cerebral Peduncle

IN MIDBRAIN. Nerve tract allowing communication between cerebellum and SC anchor to connect.

Forebrain

Composed of Thalamus, Hypothalamus, Cerebrum, Basal Nuclei, Limbic System

Thalamus

FOREBRAIN - Sensory input going to cerebrum goes through this, directed to appropriate processing region of cerebrum. Interconnected with limbic system that involves emotions/memory. Sends some motor msgs from cerebrum to spinal cord.

Hypothalamus

FOREBRAIN - Control center of autonomic nervous system and endocrine system, regulates homeostasis, controls visceral functions (secreting hormones, thermoregulation, food and water intake, sleep, memories, and emotion.)

Hypothalamus Hormones Secreted that regulate:

Pituitary Gland - growth, metabolism, reproduction, stress response. Direct: Labor Contractions, Lactation, Water Conservation.

What does the hypothalamus integrate for automatic nervous system?

Influences heart rate, blood pressure, GI secretions, pupils. Temperature Regulation: Vasodilation/Vasoconstriction.

What does the Hypothalamus’ hunger and fullness centers monitor and produce?

Monitor: Blood glucose and amino acid levels. Produce: Sensations of hunger or fullness.

Osmoreceptors

Monitor fluid levels in blood, stimulate thirst enter when dehydrated. In hypothalamus in forebrain. When dehydrated the hypothalamus secretes antidiuretic hormone, triggers water conservation in methods and thirst.

Hypothalamus sleep and circadian rythms and emotional behavior.

Regulates falling asleep and waking, controls circadian 24 hr rhythm, anger, aggression, fear, pleasure, contentment.

Basal Nuclei (Ganglia)

FOREBRAIN Gray matter deep inside white matter of brain, receive input from mid brain and motor areas of cerebral cortex. Send info back to these areas. Ket to voluntary movement, weed out unimportant signals.

Limbic System

FOREBRAIN - Contain amygdala, hippocampus.Since it is so close to the thalamus, there is a strong connection between our senses, memory, and emotions.

Amygdala

Important in emotion

Hippocampus

Important in memory and emotion.

Cerebrum

FOREBRAIN - Gray matter and part of white matter, folded into gyri and sulci. Provide 3x as much surface area.

Cerebral Cortex

Outer part of cerebrum, 2-3 mm layer, Gray matter, 40 % of brain mass (14-16 billion neurons)

Frontal Lobe

Voluntary functions, motivation, judgement, mood, planning

Parietal Lobe

sensory reception - pain pressure, temperature, tast and some visual.

Occipital Lobe

Visual center

Temporal Lobe

Hearing, smell, learning, memory, visual recognition, emotional behavior.