Compendium 9 Flashcards
Explain divisions of the spinal cord
Divided into cervical, thoracic, lumbar, sacral and coccygeal regions
Diameter changes from top to bottom- enlargements in cervical region and lumbar/sacral region that correspond with nerves that supply limbs
Cervical- supply nerves to arms
Lumbar/sacral- supply nerves to legs
Explain structure of the spinal cord
Starts at foramen magnum ends at 1st or 2nd lumbar vertebrae
Pointy end called CONUS MEDULLARIS which finishes at 2nd lumbar vertbrae
Very end region called CAUDA EQUINA which are branches of spinal nerves extending from lumbar/sacral enlargement and conus medullaris (occurs as spinal cord shorter than vertebral canal)
What are meninges
Connective tissue covering brain and spinal cord for protection, to hold CSF and to form partitions in the skull
Explain meninges layers in spinal cord
Duramata: outermost, thickest, toughest layer- as move deeper into spine there is subdural space that contains serous fluid
Arachnoid mata: thin, fine, loose, elastic - followed by subarachnoid space consigning CSF and blood vessels
Pia mata: tense, contains many blood vessels which tightly surround brain and spinal cord
Explain the structure of nerves in PNS
Axon (can be myelinated) covered by connective tissue layer called ENDONERIUM
A bunch of these is called a NERVE FASCICLE
Connective tissue surrounding one fascicle is called PERINERIUM
Outermost layer surrounding a bunch of fascicles is called EPINERIUM
Connective tissue provides strength and protection
How are spinal nerves organised
31 pairs arise, only 39 vertebral bones
Top half:
8 cervical nerves (7 bones)
8 thoracic nerves (including remaining 4 thoracic nerves- 12 bones)
Bottom half: Remaining 4 thoracic nerves 5 lumbar nerves (5 bones) 5 sacral nerves (5 bones) 1 coccygeal nerve (5 fused bones= 1 bone)
First cervical nerve come out on top of first vertebral bone (C1 on top of bone 1, C2 on top of bone 2)
C8 comes out on top of 1st thoracic bone therefore only 7 cervical bones)
From now on spinal nerves come under corresponding bone (T1 under bone 1)
What are the major parts of the brain
Forebrain: cerebrum, diencephalon
Mid brain
Hindbrain: pins, medulla oblongata, cerebellum
Midbrain, points, medulla oblongata form BRAIN STEM
What is the purpose of the brain stem
Sits under diencephalon
Connects spinal cord to rest of brain
Describe medulla oblongata
Directly connects to spinal cord at foramen magnum
Autonomic reflex centre maintaining body homeostasis
Contains groups of cells:
-cardiovascular centre: heart rate and force, blood vessel diameter
-respiratory centre: rate and depth of breathing
-other reflexes such as vomiting, swallowing, sneezing, coughing, hiccuping
Describe pons
Superior to medulla oblongata
Bridges different parts of brain to allow for communication
Contains conduction tracts running in 2 different directions: longitudinal tracts (spinal cord to higher brain centres) and transverse tracts (cerebrum to cerebellum)
Contains sleep centre which regulates rapid eye movement when sleeping
Also part of respiratory centre (works with medulla)
Describe midbrain
Smallest part of stem
Receives visual, auditory and tactile sensory input and generates reflex movements of head, eyes and body
Controls eyeball movements
Describe cerebellum
Outer grey matter, inner white matter
Highly convoluted
Communications with all of brain stem to control locomotion in association with cerebrum (coordinated movement)
Controls fine motor control e.g. Muscles in wrists, fingers, etc.
Controls posture and balance
Describe diencephalon
Contains thalamus (largest part), subthalamus, epithalamus and hypothalamus Grey matter
Describe thalamus of diencephalon
Paired structure
Sensory relay centre: relays info to cerebrum (sensory information goes here before cerebrum- all senses besides smell)
Regulates mood, memory and strong emotions
Describe hypothalamus of diencephalon
Made up of different parts
Maintain homeostasis via endocrine system
Regulates heart rate, digestive activities, sex drive and sexual pleasure
Controls muscles in swallowing, body temp
Regulates mods, motivation, emotions
Regulates sleep wake cycle
Describe cerebrum
Most superficial part of brain
Made up of elevated tissue and folds called GYRI and has grooves within called SULCI
Deep grooves called FISSURES
Left and right hemisphere divided by LONGITUDINAL FISSURE - hemisphere connected by bundle of fibres called corpus callosum
LATERAL FISSURE and CENTRAL SULCUS divide hemispheres into lobes
What are the lobes of the cerebrum
Frontal: voluntary motor function, motivation, planning, aggression, sense of smell, regulation emotional mood and behaviour
Parietal lobe: receives most sensory input except hearing, smell, taste, and vision (pain, temp, touch, ect.)
Occipital: receives and process visual input
Temporal: smell and heating input and has role in memory
Insula: located deep inside behind lateral fissure- taste information
How are the lobes in the cerebrum separated
Lateral fissure separates frontal lobe from rest of cerebrum
Central sulcus separates frontal lobe from parietal lobe
Also precentral gyrus (fold in front of central sulcus in frontal lobe) for primary somatic motor control -particularly fine voluntary movements
Postcentral gyrus/primary somatosensory cortex (fold behind central sulcus in parietal lobe) receives somatic sensory input from receptors in skeletal muscles, joints, tendons and processes it (pain, pressure)
It is first synapses in thalamus before transmitted here
Grey and white matter of cerebrum
Grey matter = outer
Where consciousness is formed
Allows us to communicate, remember, understand, ect.
White matter = inner/deep
Communication between cerebral areas and cortex and lower CNS structures
What is the limbic system
Runs through medial aspect of hemispheres and diencephalon
Runs around border of corpus callosum
Group of structures that have role in memory, developing new neurological pathways and control emotion and emotional gestures
Describe meninges layers of the brain
Dura mata: outermost, fibrous connective tissue that contains the following:
- periosteal dura: connects to bony skull and also meningeal dura (deeper) which continues with the dura mata of the spinal cord
- some parts of brain contain these two layers and have a dural venous sinus which contain veins that collect blood that nourishes brain and also dural folds which are connective tissue partitions extending deep into brain which hold brain in place and stop excessive movement
- if no sinus then two layers fuse together
- between whole dura mata and next layer there is subdural space with serous fluid
Arachnoid mata: similar structure to in spinal cord- followed by subarachnoid space with CSF and blood vessels
Pia mata: very small blood vessels sit tightly over brain surface
Describe the ventricles of the brain
Brain has 4 ventricles that are continuous with each other and are lined with ependymal cells
Largest= lateral ventricle which is paired and extends into each hemisphere
4th is brain stem which is continuous with central canal of spinal cord
These spaces are where CSF is produced
Describe cerebrospinal fluid
Most produced by choroid plexus which in brain is specialised ependymal cells and support tissue
Protects brain from trauma and provides buoyancy (brain floats which reduces feeling of its weight and takes pressure off structures underneath)
Similar to plasma but less proteins, different ionic concentrations
Some CSF comes from water and solutes in blood moving through ventricles
Provides nutrients to brain and spinal cord
Circulates through ventricles, central canal of spinal cord and subarachnoid space
Cilia of cells help to circulate CSF
Describe cranial nerves
12 pairs arise from brain
Emerge directly out of brain and carry info from brain to body and back to brain
Can be sensory motor and or parasympathetic functions
Describe anatomy of autonomic nervous system
Sympathetic division: cell bodies between T1 and L2 called thoracolumbar division
Parasympathetic division: cell bodies in sacral region between S2 and S4 also in cranial nerve nuclei in brain stem called craniosacral region
Similarities between parasympathetic and sympathetic divisions
Both systems can serve same organs however will have opposing effects
Can both regulate heart rate, blood pressure, airway in lungs, pupil of eye, digestive tract, glands
How is the ANS regulated
Occurs mostly via autonomic reflexes
Also influenced by CNS particularly in hypothalamus which integrates info which is communicated to other parts of the brain so a response can be executed
What is autocrine
Released by cells and have local effect on same cell type from which chemical signals released
What is paracrine
Released by cells and affect other cell types locally without being transported by blood
What is an endocrine
Produced by cells of endocrine glands, enter circulatory system and affect distant cells
What are characteristics of the endocrine system
Regulation over time
Glands secrete hormones which are produced in small quantities, transported some distance, act on target tissues elsewhere in body, mostly steroid or amino acid based
Hormone secretion can be:
Acute- sudden release due to stimuli (adrenaline from stress)
Chronic- small variations over long periods (thyroid hormones)
Episodic- e.g. Estrogen and progesterone during menstrual cycle
Target cells respond to hormone as they have correct receptor
Similarities between endocrine and nervous systems
Both associated with brain
Same chemical messenger can be used as a neurotransmitter and hormone
Are cooperative
Differences between endocrine and nervous systems
Transport mode (blood vs. axon)
Speed of response
Duration of response
How does the CNS control endocrine system
CNS can influence hormone release through hypothalamus which synthesis neurohormones and controls release of hormones from anterior pituitary gland
Adrenal medulla arose from neural tissue, secretes adrenaline and noradrenaline
Hypothalamus controls hormone release through releasing and inhibiting hormones it releases itself
How does the endocrine system control CNS
Endocrine secretes hormones that maintain vernal health of neural tissue, regulates minerals necessary for neural function, needed for growth and function of NS
List endocrine glands
Pineal gland Hypothalamus Pituitary gland Thyroid gland Parathyroid gland Thymus gland Adrenal glands Pancreas Ovary Testes
What is a tropic hormone
Acts on another endocrine gland which then produces another hormone
Mainly produced by anterior pituitary gland
What is a non tropic hormone
Hormones that act directly on a target cell to produce an effect
Produced by most endocrine glands
Example: protein synthesis by growth hormones and prolactin acting on breast cells
Explain the role of the hypothalamus and pituitary gland
Hypothalamus regulates secretions of anterior pituitary
Posterior pituitary is an extension of hypothalamus (nervous tissue)
Pituitary produces 9 major hormones, is a master gland as it produces hormones that act on other glands as well as controlling hormone production
Describe structure of pituitary gland
Posterior: extends from hypothalamus via infundibulum and secretes neuropeptides that are made by hypothalamus and sent to posterior for release
- stimuli in NS causes neurons in hypothalamus to increase or decrease frequency of action potentials
- action potentials conducted along neurons towards posterior, axon terminals of these neurons store neuro-hormones
- when potential reaches axon terminal neurohormones released into blood stream and travel to target tissue
Anterior: synthesis and secretes hormones
-hypothalamus recognised hormone imbalance or stimulus so produces releasing hormones which travel through capillaries to anterior where hormones will act on particular cells that will produce a certain hormone that acts on a target tissue
List anterior pituitary hormones
Growth Thyroid stimulating Adrenocorticotropic Melanocyte-stimulating Lutenising hormone and follicle stimulating Prolactin
Explain growth hormone
Acts on most body cells
Stimulated amino acid uptake, fat breakdown, promotes bone and cartilage growth, regulates nutrient levels in blood after meals
Explain thyroid stimulating hormone
Stimulated thyroid to secrete T3 and T4 which regulate metabolic rate
Influences appetite, temperature, muscle function
Explain adrenocorticotropic hormone
Stimulate adrenal cortex to secrete cortisol (stress), aldosterone (salt balance and blood pressure) and androgens (development and maintenance of male sex characteristics)
Explain melanocytes-stimulating hormone
Causes melanocytes to produce more melanin
Explain lutenising and follicle stimulating hormone
Both regulate production gametes and reproductive hormones
Testosterone in males
Estrogen and progesterone in women
Explain prolactin
Role in milk production
List hormones of posterior pituitary gland
Oxytocin
Antidiuretic
Explain oxytocin
Uterine contractions during birth
Ejection of milk
Explain antidiuretic hormone
Acts on distal tubule of kidney to increase water reabsorption (less urine produced)
Explain negative feedback
Anterior pituitary secrete tropic hormone which travels in blood to target endocrine cell
Cell then releases hormone itself and will travel to its target
Hormones effect on target cell will have negative feedback effect on hypothalamus
Message send back to hypothalamus so anterior pituitary decreases secretion of the tropic hormone
Explain positive feedback
Anterior pituitary secretes tropic hormone will travels in blood to endocrine organ and then to target organ or cell
Positive feedback on hypothalamus and anterior pituitary to increase secretion of tropic hormone
How is adrenal medulla different
Controlled by sympathetic division NS not pituitary gland
