Functional organisation of nervous systems Flashcards
What is included in the CNS?
Brain and spinal cord
What do afferent neurons do?
Send information from the periphery to the CNS
What do efferent neurons do?
Send information from the CNS to the periphery
What is a nerve?
A group of axons from many neurons
What connective tissue surrounds the axon?
Endoneurium
What is a fasicle?
Groups of axons bundled together and surrounded by perineurium
What are groups of fasicles surrounded by?
Epineurium
Describe the pathways of the vertebrate nervous system
- Internal/external sensory stimuli
- Afferent (sensory) branch
- Brain/spinal cord
- Efferent branch
What are the 2 divisions of the efferent branch of the nervous system?
Motor division and autonomic division
What does the motor division of the efferent branch control?
Skeletal muscle
What are the 3 divisions of the autonomic division of the efferent branch
Sympathetic nervous system, parasympathetic nervous system and the enteric nervous system
What does the sympathetic nervous system of the afferent branch control?
Smooth muscle, cardiac muscle, exocrine glands and some endocrine glands
What does the parasympathetic nervous system of the afferent branch control?
Smooth muscle, cardiac muscle, exocrine glands and some endocrine glands
What does the enteric nervous system of the afferent branch control?
Digestive organs
What are the 4 main parts of the brain?
Forebrain
Midbrain
Cerebellum
Pituitary
What does the forebrain do?
Has a central role in the processing of information related to complex cognitive activities, sensory and associative functions and voluntary motor activites
What does the midbrain do?
Associated with vision, hearing, motor control, sleep and wake cycles, arousal(alertness) and temperature regulation
What does the cerebellum do?
Receives information from the sensory systems, the spinal cord and other parts of the brain then regulates motor movements
What does the pituitary gland do?
Secretes hormones controlling; growth, blood pre4ssure, energy management, sex organ function, thyroid glands, metabolism, breastfeeding, water and salt concentration in the kidneys, temperature regulation and pain relief
Describe the 3 main parts of the mammalian brain
Left hemisphere
Right hemisphere
Corpus callosum
What does the left hemisphere control?
The right side of the body and speech
What does the right hemisphere control?
The left side of the body and perception of spatial relationships
What is the corpus callosum?
A bundle of axons which connects the two hemispheres
What are gyri?
Folds in the brain
What are sulci?
Grooves in the brain
What do the gyri and sulci do?
Increase the surface area of the brain
What is increased surface area in the brain linked with?
Greater functional complexity and intelligence
What is the blood brain barrier made of?
Formed by endothelial cells of the capillary layer
How do selected solutes enter the brain?
Tight junctions between the cells allow selected diffiusion
What does the blood brain barrier do?
Maintains homeostasis in the brain and prevents toxins from entering
What are astrocytes?
Non neural glial cells that are involved in many CNS functions including biochemical support of the BBB
What are pericytes?
Cells that wrap around the endothelium and are involved in the formation of the BBB by forming tight junctions and regulating vesicle trafficking
Where is the spinal cord in vertebrates?
Enclosed in the spine
What does grey matter contain?
Unmyelinated cell bodies, dendrites and axon terminals and is where most synapses are located
What does white matter contain?
Myelinated axons projecting from and to the brain
Where do spinal nerves send information?
To and from the periphery
What does the dorsal tract of the spinal cord do?
Receives sensory information from the periphery tracts- afferent
What does the ventral tract of the spinal cord do?
Sends information to muscles and organs- efferent
What does the autonomic nervous system do?
Regulates unconscious bodily functions including; heart rate, digestion, respiratory rate, pupillary response and urination
What is dual innervation?
Where organs will receive signals from both the sympathetic and parasympathetic nervous systems
Why is the PNS and the SNS antagonistic?
To maintain homeostasis
What is the basal tone in PNS and the SNS?
They will still fire action potentials even at rest to allow for precise regulation and control
What does the parasympathetic divison do?
The long preganglionic cholinergic neuron sends signals to the autonomic ganglia and the short postganglionic cholinergic neuron sends signals to the organs
What does the sympathetic division do?
The short preganglionic cholinergic neuron sends signals to the autonomic ganglia and the long postganglionic cholinergic neuron sends signals to the organs
What regulates the ANS?
Many areas of the brain including the hypothalamus
How does the hypothalamus communicate with the ANS?
Either directly or through the reticular neurons in the brainstem
What is the role of the hypothalamus?
The portion of the brain that maintains homeostasis
Links the endocrine and nervous systems
Produces hormones that stop and start the production of other hormones throughout the body
Closely associated with the pituitary gland and adrenal glands
What is the HPA axis?
The hypothalamus-pituitary-adrenal axis
What does the amygdala do?
Has a primary role in memory formation duration during emotional events, decision making, facial recognition and emotional responses
Is rich in androgen receptors and is larger in males
Describe how the amygdala propagates a response to danger
The amygdala receives signals from the cortex signalling there is danger
The signal is sent to to the spinal cord which activates the sympathetic nervous system
The adrenal gland releases norepinephrine and epinephrine (adrenaline) which is then bound to various tissues
Blood is diverted, heart rate and blood pressure is increased
Simultaneously the hypothalamus activated the endocrine system to release cortisol
Cortisol causes the muscles to release amino acids which are converted in the liver to glucose- gluconeogenesis
