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The Brain (Cranial nerves (cranial-nerves1, IV. Trochlear - Motor - Serves…
The Brain
Cranial nerves
IV. Trochlear - Motor - Serves the supirior oblique eye muscle
V. Trigeminal - motor and sensory - sensory from face and mouth, chewing
VI. Abducens - motor - abducts the eye
VII. Facial - motor and sensory - facial expression, taste
VIII. Vestibulochlear - sensory - hearing, balance
IX. Glossopharyngal - motor and sensory - taste, gag reflex
X. Vagus - sensory and motor - gag reflex, parasympathetic innervation, viscara autonomic
XI. Accessory - motor - muscles in head and neck
III. Oculomotor - motor - serves muscles of eye
II. Optic - sensory - vision
I. Olfactory - sensory - smell
XII. Hypoglossal - motor - lower throat swallowing
Four parts
Brain stem
Medulla oblongata - all sensory that goes through brain goes through this
Respiratory center - works in conjunction with pons, controls the rate of respiration
Vasomotor center - controls dilation and constriction
Cardiac center - helps with heart rate and force of contraction
Coughing, vomiting, sneezing, swallowing
Pons - links brain stem with cerabellum
Pons make a bridge between midbrane and madula oblongata
Coordinates voluntary movements
Apneustic and Pneumotaxic center - helps regulate respiration
Midbrain - above pons, below diencephalon .
Cerebral peduncles - vertical pillars that hold up cerebrum. They carry motor impulses between cerebral cortex, pons, and spinal cord
Corpora quadrigemina (superior/ inferior colliculi) - visual and auditory reflexes
Superior part - responsible for visual, movement of eyeball
Inferior part - auditory, turning head to hear sound
Cerebellum
Coordination of muscular activity - making smooth movements
Balance and equilibrium
Diencephalon
Links between two cerebral hemispheres
Thalamus
Relay station for sensory impulses except olfactory(smell)
Hypothalamus
Maintains homeostasis by regulating visceral activities
Monitors heart rate, blood pressure, blood osmotic pressure (water & electrolytes), body temp, pituitary, ANS, rage and aggression
Epithalalamus
Most dorsal part
Pineal gland- secretes melatonin which synchronize the body's rhythmic changes or biological clock
Cerebrum
Largest part of brain
Cerebral gray matter
Folds of brain increase amount of gray matter
Is divided into four lobes
Cerebral white matter
Mostly myelinated axons
Corpus callosum - unites the cerebral hemispheres
Cerebrospinal fluid
Provides a liquid cushion fro boyancy
Increases brains weight by 90%
Made by choroid plexuses (made by neuroglia cells)
Each one is inside of a ventricle
Moves through ventricles
Lateral ventricles (2)
Behind the corpus callosum (have one on each side of hemisphere)
Third ventricle
Formed by a space where we put the two hemispheres together
Formed between hypothalamus and thalamus on each side
Fourth ventricle
Formed by the junction of cerebellum with the brain stem
Flow
Choroid plexus(in all ventricles), lateral ventricle, third ventricle, through interventricular foramen, fourth ventricle, through cerebral spinal fluid, to subarachniod space, to saggital sinus
Meninges
Dura mater
Two layered sheet of fibrous connective tissue
Dural sinuses
No epidural space
Arachniod mater
Subdural space
Subarachniod space
Pia mater
Gentle mother
Small blood vessels
Dural folds
Tentorium cerebelli
Seperates the cerebral hemespheres
Blood brain barrier
Tight junctions with capillary endothelial cells
Makes them least permiable of all capillaries in body
Selective about what gets into brain
Can enter - Glucose, fats, fatty acids, oxygen, carbon dioxide, fat soluble molecules, essential amino acids, and some electrolytes
Cannot enter - Bloodborne wastes, proteins, certain toxins and most drugs
Autonomic nervous system
Controls involuntary functionS. Heart rate, digestion, urination , etc
Motor goes to somatic or ANS
Somatic reflexes stimulate the skeletal muscles
Somatic reflex- 1, receptor 2, sensory neuron 3, Integration center 4, motor neuron 5, effector
Difference between sympathetic & parasympathetic
Pupil- S-dialation. P-constriction
Lens- S- far focus. P- near focus
Salivary glands- S- very viscous. P- very watery
Heart- S- increased rate and pressure. P- decreased rate and pressure
Lungs- S- dilation of respiratory pathways. P- constriction of respiratory pathways
Gastrointestinal- S- decreased mobility. P- increased mobility
Kidneys- S- decreased filtration rate. P- Increased filtration rate
Male genitalia- S- ejaculation. P- erection
Sweat glands- S- increased activity. P- no innervation
Arteries to skeletal muscle- S- dilation. P- no innervation
Veins- S- variable depending on neurotransmitter. P- no innervation
Vascular smooth muscle- S- variable depending on neurotransmitter. P- relaxation
Reflexes
All involve pathway called arc
Input contains receptor and sensory neuron
Autonomic- receptor on organ or gland
Processing center
Integration center / gray matter
Output
Autonomic uses 2 neurons (pre & post ganglionic fibers) (sympathetic has 1)
Two divisions of ANS
Sympathetic and parasympathetic
Regulate normal functions and homeostasis
Dual innovation - most organs glands or smooth muscle save invite from both the parasympathetic and sympathetic
Usually opposing effects
Each have own set of nerves that connect to major visceral organs and body
Enteric NS- works without instruction from CNS
Sympathetic division
Fight or flight.
Preganglionic anon linked to post ganglionic neuron
Preganglionic runs from T1-L2. Short in length
Post ganglionic- long
Sympathetic trunk ganglia
Two columns of ganglia that run along spinal cord
Cervical ganglion, superior, metal, and inferior
Postganglionic goes from the ganglionic to the head and thoracic organs
3 other ganglia
Celiac
Superior mesentric
Inferior mesenteric
The postganglionic connected below the diaphragm
Most postganglionic neurons Passt through plexuses on to Target organs
Parasympathetic division
Resting and digesting
Murder arises from the cranial and sacral
4 ganglia (that connect to target organs in the head)
Ciliary - eye
Pterygopalatine - roof of mouth
Submandibular
Otic- salivary glands
The preganglionic neuron is linked to the post ganglionic anon
Preganglionic nerves arise from central nerves, three, seven, nine, and 10. Also arise from S2-S4 & are long
Postganglionic are short
Neurotransmitters and receptors
Help regulate our unconscious activity
3 major neurotransmitters
Acetylcholine ACh - binds to cholinergic receptors
E - epinephrine
Bind to adrenergic receptors (bind adrenaline)
NE - norepinephrine
In sympathetic division
Adrenergic
Alpha receptors (first receptors)
Alpha 1 - responsible for excitation
Alpha 2- inhibitory
Alpha blocker ( find two alpha receptor on smooth muscle and decreases vasoconstriction )
Beta receptors
Heart, excitation. Lungs, and addition of bronchioles, construction. Beta blockers, propanolol, lolpressor, and albuterol, peoventil, and ventolin.
Anna parasympathetic division
Cholinergic (ACh)
First receptors are nicotinic receptors. Can be opened by nicotine
Acetylcholine binding produces simulation
Muscarinic
Acetylcholine binding produced a simulation or inhibition
Visceral function
Baroreceptors - stretch receptors. Located in digestive tract, bladder, carotid artery, & lungs. Function- stimulate or inhibited a reaction from a particular organ
Chemoreceptors - regulate different chemicals within body Location- Respiratory center of the madula oblongata. Function- regulate breathing
