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55 terms

Lab Practical 4

STUDY
PLAY
Components of a Reflex Arc
Sensory Receptor
Sensory Neuron
Integrating center
Motor neuron
Effector
Patellar reflex
Hammer strikes tendon
Tendon bends and stretches attached muscle
Muscle contracts to relieve stretch
Flexor and Crossed Extensor Reflexes
Paired reflex
Corneal reflex
Mediated by Trigeminal Nerve V- causes the blinking action
Pupillary light and consensual reflex
Paired reflexes, shining light leads to pupil constriction in both eyes
Pupillary reflex- ipsilateral
Consensual reflex- contralateral side
Ciliospinal reflex
SNS causes vasodilation of the pupil on the same side as a stimulus
Salivary reflex
Mediated by cranial nerve Facial VII, and Glossopharangeal IX. Stimulate glands to increase saliva production at the sight or smell of food
Somatic Sensation
General- Originate form either sensory somatic receptors (skin or skeletal muscles) or visceral somatic receptors
Special- From special sense organs like eye, inner ear, nose, taste buds
General somatic receptors
Modified sensory nerve cell endings (sensory receptors and neurons are on the same cell)
(Sensory neurons are house in special places and have cells that communicate with the sensory neurons)
Meissner's Corpuscles
Location: Dermal papillae of hairless skin
Stimuli: Touch and pressure
Hair Root Plexus
Location: surrounds hair follicles
Stimuli: Touching hair
Pacinian Corpuscles
Location:Subcutaneous and submucosal tissue, joints, tendons, and muscles
Stimuli: Touch and pressure
Merkel Discs
Location: Associated with Merkel cells in stratum basale layer of epidermis
Stimuli: Touch and pressure
Ruffini's Corpuscles
Location: Dermis, ligaments, tendons
Stimuli: Stretching of digits and limbs
Muscle spindles
Location: Most skeletal muscles
Stimuli: Changes in muscle length
Tendon organs
Location: junction of tendons and muscles
Stimuli: changes in joint position and movement
Warm receptors
Location: Dermis
Stimuli: Thermoreceptor of temps between 32-48 C
Cold receptors
Location: Dermis
Stimuli: Thermoreceptor of temps 10 to -40 C
Nocireceptors
Location: every body tissue
Stimuli: pain receptors, harmful stimuli
Palm vs. Calf
Palm- has a smaller receptor field i.e. a greater density of receptors
Calf- larger receptor field has less density of receptors
Tactile localization
Has motor and sensory components along with showing a size of a receptor field
Dermatomes
An area of skin that is mainly supplied by a spinal nerve
Glaucoma
2nd greatest cause of blindness due to increased pressure in the eye
Aqueous humor builds up due to angle blockage
Open angle (chronic), Angle closure (acute), Congenital (from birth)
Layers of the eyeball
Fibrous Tunic
Middle vascular tunic
Inner retina
Fibrous tunic
Cornea- transparent portion
Sclera- tough, white portion with the sclera venous sinus (junction of cornea and sclera)
Middle vascular tunic
Iris and pupil
Ciliary body
Choroid
Ciliary body
Ciliary muscle- controls the shape of the lens
Ciliary processes- folds that protrude from the ciliary body toward the lens, secretes aqueous humor
Choroid
Most posterior part of the vascular tunic
Contains blood vessels to nourish retina
Inner retina
Ora serrata- serrated boundary between ciliary muscle and the retina
Pigmented outer later and neutral inner layer that contain photoreceptors and associated neurons
Initial segment
Also the trigger area, the beginning of an axon where the action potential is generated
astrocytes
Covers neurons and blood vessels to keep them in place, guides neurons during development, and form a blood brain barrier
In the CNS
Ogliodendrocytes
Form myelin sheaths around axons
In the CNS
Schwann Cells
Form myelin sheath around axons
In the PNS
Satellite cells
Give support to PNS neurons and regulate their chemical environment
White matter
Groups of myelinated axons in the CNS
Four regions of the brain
1. Cerebrum
2. Diencephalon
3. Brain stem
4. Cerebellum
Basal ganglia
Areas of deep gray matter composed of paired nuclei (clusters of cell bodies in the CNS)
Corpus callosum
Commissural fiber tract that connects the hemispheres
Fornix
Tract of arches association fibers
Internal capsule
Projection fibers that connect the cerebral cortex to the brain stem and spinal cord
Thalamus
Divided in half, connected by the intermediate mass
Serves as the central relay station
Epithalamus
Included the pineal gland
Hypothalamus
Controls bodily functions, homeostasis, and has a hormonal function
Has infundibulum, pituitary glands, and mammillary bodies
Infundibulum
Connects the pituitary gland to the hypothalamus
Mammillary bodies
Relay stations for taste and smell
The Brain Stem
Has the medulla oblongata, the pons, and the midbrain
Medulla oblongata
Respiratory and cardiovascular control center
Reflex centers for coughing, vomiting, and sneezing
Pons
Assist medulla in controlled breathing
Relays info to the diencephalon and the cerebrum
Midbrain
Has cerebral pundicles- (connects upper and lower brain area
Corpora quadrigemina- 4 colliculi
Cerebellum
Regulates posture and balance
Smooths skilled muscle movements
Cranial meninges
Protect the brain
Dura (periosteal and meningeal), arachnoid, and pia mater
Choroid plexus
Tiny blood vessels that allow plasma to leak through
Interventricular foramen
Goes in between the lateral ventricles and the third ventricle
Cerebral aqueduct
Goes in between the third ventricle and the fourth ventricle
Flow of the CSF
1. Epdendymal cells of choroid plexus in lateral ventricles (filtered from blood plasma
2. Third ventricle
3. Fourth ventricle
4. Can either go to the medial & lateral apertures of 4th ventricle or the central canal of the spinal cord
5. Subarachnoid space of brain & spinal cord
6. Arachnoid villi
7. Superior sagittal sinus returns CSF to blood