How does it all work? Flashcards
Describe the spinal cord
- Extends from the foramen magnum to the first or second lumbar vertebrae
- Can be divided into cervical, thoracic, lumbar, sacral and coccygeal (coxy-geal) regions
- 31 pairs of spinal nerves
What are the Meninges?
-Meninges: the connective tissue covering the spinal cord and brain.
What are the functions of the meninges?
- Protects the central nervous system and its blood vessels
- Contains the cerebrospinal fluid
- Forms partitions in the skull
What is the Dura Mater
- Periosteal dura
- Dural venous sinus
- Venous blood
- Dural folds
- Meningeal dura
- Subdural space
- Serous fluid
What is the Arachnoid Mater
Subarachnoid space
-Cerebrospinal fluid and blood vessels
What is the Pia Mater?
-Has many small blood vessels
In the spinal cord where do the sensory & motor neurons travel?
- Sensory neurons travel through the dorsal roots
- Motor (somatic and autonomic) neurons travel though the ventral roots
- Spinal nerves contain sensory neurons and motor (somatic and autonomic)
What are the cell bodies of the motor neurons in?
-Cell bodies of motor neurons are in horns of grey matter
=Somatic motor neuron cell bodies in anterior (ventral) horn (motor horn)
=Autonomic motor neuron cell bodies in lateral horn
What do the Endoneurium, Perineurium & Epineurium surround?
-Endoneurium
o Surrounds each axon and its associated Schwann cells
-Perineurium
o Surrounds a group of axons or a nerve fascicle
-Epineurium
o Surrounds a group of fascicles
What are the parts of the brain?
-Forebrain o Cerebrum o Diencephalon -Midbrain -Hindbrain o Pons o Medulla oblongata o Cerebellum
What is the function of the Medulla Oblongata and the centres?
-Autonomic reflex centre maintaining body homeostasis
-Cardiovascular centre
o Regulates heart rate, force of heart contraction and blood vessel diameter
-Respiratory centre
o Regulates rate and depth of breathing
-Other reflexes
o Swallowing, vomiting, hiccupping, coughing and sneezing
What is the function of the pons, what does it contain?
-Pons = bridge
-Contains conduction tracts:
o Longitudinal tracts from the spinal cord to higher brain centres
o Transverse tracts form the cerebrum (motor cortex) and cerebellum
-Sleep centre
o Rapid eye movement
-Respiratory centre
What is the function of the mid brain?
- Receives visual, auditory and tactile sensory input generating reflex movements of the head, eyes and body
- Controlling movement of the eye
What is the function of the Cerebellum?
- Cerebellum = little brain
- Controls locomotion, in association with the cerebrum
- Controls fine motor control
- Controls posture and balance
What are the parts of the Diencephalon?
- Thalamus
- Subthalamus
- Epithalamus
- Hypothalamus
What is the function of the Thalamus?
-Sensory relay centre or “gateway”
o Anything you hear, see, feel by touch, but NOT smell
-Regulates mood, memory and strong emotions e.g. fear and rage
What are the functions of the Hypothalamus?
- Maintains homeostasis via the endocrine system
- Regulates heart rate
- Regulates digestive activities (food intake, water balance and thirst)
- Controls muscles in swallowing
- Controls body temperature
- Regulates the sex drive and sexual pleasure
- Regulates mood, motivation and emotions
- Regulates the sleep-wake cycle
Name and describe the parts of the Cerebrum
- Gyri – elevated tissue or folds
- Sulci – grooves
- Fissures – deep grooves
- Longitudinal fissure – separates left and right hemisphere
- Lateral fissure – separates temporal lobe from rest of the cerebrum
- Central sulcus – separates frontal lobe from parietal lobe
What are the lobes of the Cerebrum?
- Frontal
- Parietal
- Occipital
- Temporal
- Insula
What is the function of the Precentral & Postcentral Gyrus?
- Precentral gyrus – primary somatic motor cortex
- Postcentral gyrus – primary somatic sensory cortex (aka primary somatosensory cortex)
What is the function of the frontal & parietal lobe?
- Frontal lobe – voluntary motor function, motivation, planning, aggression, sense of smell, regulation of emotional behaviour and mood
- Parietal lobe – area which receives most the sensory input, except for smell, hearing, taste and vision
What is the function of the occipital & temporal lobe and the insula?
- Occipital lobe – receives and processes visual input
- Temporal lobe – receives and processes smell and hearing, and has a role in memory
- Insula – Receives and processes taste information
What does the grey & white matter in the cerebral cortex contain?
-Grey matter in the cerebral cortex
o Cell bodies, dendrites, unmyelinated axons, axon terminals and neuroglial cells
-White matter in the cerebral medulla
o Myelinated axons
-Corpus callosum – connects two cerebral hemispheres together
What is the Limbic System?
- Role in memory
- “Emotional brain”
What is produced in the ventricles, what are they lined with and what are the 1st and 2nd ventricle?
- Four ventricles that are continuous with each other
- Lined with ependymal cells
- Lateral ventricle: first and second ventricle
- Third ventricle
- Fourth ventricle
- Cerebrospinal fluid produced in ventricle
What is the function of the cerebrospinal fluid?
- Most cerebrospinal fluid is produced by the choroid plexus
- Fluid found around the brain and spinal cord
- Protects the brain and spinal cord from trauma and provides buoyancy to the brain
- CSF composition: similar to blood plasma but less proteins and different ionic concentration
What is the anatomy of the autonomic NS?
Sympathetic division -Thoracolumbar division o T1 – L2 Parasympathetic division -Craniosacral division o S2-S4 o Cranial nerve nuclei
What responses can be generated by both ANS regulate?
- Heart rate
- Blood pressure
- Airways in lungs
- Digestive tract
- Glands (salivary, gastric, lacrimal)
- Pupil of the eye
What is the Sympathetic & Parasympathetic NS?
-Sympathetic division: o Fight or flight o ‘E division’ -Exercise, emergency, excitement and embarrassment -Parasympathetic division: o Rest and digest o ‘D division’ -Digestion, defecation and diuresis
What are the regulation of the autonomic NS?
-Autonomic regulation occurs mostly via autonomic reflexes
o Reflexes are an automatic response to a stimulus and are homeostatic
-Autonomic reflex activity is also influenced by the CNS, in particular the hypothalamus
What is Autocrine, Paracrine, Neurotransmitter & Endocrin?
Autocrine
-Released by cells and have a local effect on same cell type from which chemical signals released.
Paracrine
-Released by cells and affect other cell types locally without being transported in blood.
Neurotransmitter
-Produced by neurons and secreted into extracellular spaces by presynaptic nerve terminals; travels short distances; influences postsynaptic cells.
Endocrine
-Produced by cells of endocrine glands, enter circulatory system, and affect distant cells.
What are the characteristics of the endocrine system?
- Body control system where regulation requires duration rather than speed
- Glands that secrete chemical messengers (hormones) into circulatory system (blood)
What are hormone characteristics in the endocrine system and how can the secretion be??
-Hormone characteristics
o Produced in small quantities
o Transported some distance in circulatory system
o Acts on target tissues elsewhere in body
-Hormone secretion can be:
o Acute - sudden release due to stimulus, e.g. adrenaline in response to stress
o Chronic – small variations over long periods, e.g. thyroid hormones
o Episodic – e.g. estrogen & progesterone during menstrual cycle
-Target cells respond to a hormone because they have the correct receptor
What are the similarities between the nervous & endocrine system?
-Both systems associated with the brain
o Endocrine – hypothalamus
-May use same chemical messenger as neurotransmitter and hormone.
o E.g. epinephrine
-Two systems are cooperative
o E.g. some parts of endocrine system innervated directly by nervous system (adrenal medulla)
What are the differences between the nervous & endocrine system?
-Mode of transport o Axon o Blood -Speed of response o Nervous – instant/milliseconds o Endocrine – delayed/seconds -Duration of response o Nervous – milliseconds/seconds o Endocrine – minutes/days
What is the central nervous system control over the endocrine system?
-CNS control over endocrine
o CNS can influence hormone release through hypothalamus
-Hypothalamus synthesizes neuro-hormones and controls hormone release from anterior pituitary
o Adrenal medulla
-Central part of adrenal gland, arose from neural tissue, secretes adrenalin & noradrenalin
What is the endocrine systems control over the central nervous system?
-Endocrine control over CNS
o Endocrine system secretes hormones that
-Maintain general health of neural tissue
-Regulate minerals necessary for neural function
-Are needed for normal growth and function of nervous system
What are the functions of the endocrine system?
- Metabolism
- Control of food intake and digestion
- Tissue maturation
- Ion regulation
- Water balance
- Heart rate and blood pressure regulation
- Control of blood glucose and other nutrients
- Control of reproductive functions
- Uterine contractions and milk release
- Immune system regulation
What is the function of the pituitary & hypothalamus?
-Where nervous and endocrine systems interact
-Hypothalamus regulates secretions of anterior pituitary
-Posterior pituitary is an extension of the hypothalamus
-The pituitary gland produces nine major hormones that
o Regulate body functions
o Regulate the secretions of other endocrine glands
What is the structure of the pituitary gland?
-Posterior pituitary o Extension of the nervous system via the infundibulum o Secretes neuropeptides -Anterior pituitary o Synthesizes and secretes hormones
How does the hypothalamus communicate with the anterior gland for hormone release?
- Stimuli within nervous system regulate secretion of releasing hormones from neurons in hypothalamus
- Releasing hormones pass to anterior pituitary
- Releasing hormones stimulate the release of hormones from anterior pituitary
- Anterior pituitary hormones travel in blood stream to target tissue, which may be another endocrine gland
What are the functions of the anterior hormones growth hormone, thyroid stimulating & Adrenocorticotrophic?
- Growth hormone (GH)
- Acts on most cells of body
- Stimulates uptake of amino acids; protein synthesis
- Stimulates breakdown of fats to be used as an energy source
- Promotes bone and cartilage growth
- Regulates blood levels of nutrients after a meal - Thyroid stimulating hormone (TSH)
- Stimulates thyroid to secrete T3 and T4 - Adrenocorticotropic hormone (ACTH)
- Stimulates adrenal cortex to secrete cortisol and aldosterone
What are the functions of the anterior hormones melanocyte stimulating, luteinising/follicle stimulating and prolactin?
- Melanocyte-stimulating hormone (MSH)
-Causes melanocytes to produce more melanin - Luteinizing hormone (LH) & Follicle-stimulating hormone (FSH)
-Both hormones regulate production of gametes and reproductive hormones
o Testosterone in males
o Estrogen and progesterone in females - Prolactin
-Role in milk production
How does the hypothalamus communicate with the posterior gland for hormone release?
- Stimuli within nervous system cause neurons in hypothalamus to increase or decrease action potential frequency
- AP’s conducted along neurons from hypothalamus to posterior pituitary. Axon terminals of these neurons store neuro-hormones.
- AP’s cause release of neurohormones into circulatory system
- Posterior pituitary hormones travel in blood stream to target tissue
What are the functions of the posterior hormones antidiuretic and oxytocin?
- Antidiuretic hormone (ADH).
- Stimulates increased reabsorption of water from nephrons, so less (more concentrated) urine is produced (water is conserved by body) - Oxytocin
- Uterine contractions during birth
- Ejection of milk from lactating breast
In a negative feedback how is the hormone secretion controlled?
- Anterior pituitary secretes a tropic hormone which travels in blood to target endocrine cell
- Hormone from target endocrine cell travels to its target
- Hormone from target endocrine cells has negative feedback effect on hypothalamus and anterior pituitary to decrease secretion of tropic hormone
In the pancreas how is insulin secretion regulated?
-Located along near intestine and stomach; retroperitoneal
-Exocrine gland
o Produces pancreatic digestive juices
-Endocrine gland
o Consists of pancreatic islets
-Alpha cells - secrete glucagon
-Beta cells - secrete insulin
In a positive feedback how is the hormone secretion controlled?
- Anterior pituitary secretes a tropic hormone which travels in blood to target endocrine cell
- Hormone from target endocrine cell travels to its target
- Hormone from target endocrine cells has positive feedback effect on hypothalamus and anterior pituitary to increase secretion of tropic hormone
What is the adrenal medulla?
- Near superior poles of kidneys
- Inner medulla; outer cortex
- Medulla – formed from neural crest, sympathetic
