Nervous system Flashcards
Know for end of semester exam
What is a neuron
basic structural unit of the nervous system.
Highly specialised cell that conduct electrical signals along axons.
What are the oligodentrocytes
- the myelinating cell of the CNS
- - can myelinate several axons
What does myelin do?
Tightly wraps around the cell membrane
Myelin basically represents fat
Contrast ‘white matter’ to ‘grey matter’
white matter: fat is pale/yellow characterizing areas of the CNS with higher myelination
Grey matter: composed of less myelinated axons (higher density of cell bodies)
Describe meninges: Pia mater
closest layer to brain, follows all irregularities of brain surface
Describe meninges: Arachnoid mater
Subdural layer with projections to pia (forms subarachnoid space for CSF)
Describe meninges: dura mater
external dense connective tissue (protection)
What are the dural folds?
- divide the cranial cavity and help to hold the brain in place
- houses the venous sinuses
what comprises the forebrain?
- cerebrum
- thalamus, hypothalamus (Diencephalon)
What comprises the midbrain
- narrow connection of forebrain to hindbrain
- contains cerebral aqueduct
What comprises the hindbrain
- medulla oblongata
- pons
- cerebellum
What are the folds of the brain called?
Gyri (singular = gyrus)
What are the grooves of the brain called
Sulci (singular = sulcus)
Describe the following features of the somatic section of the nervous system: CONTROL EFFERENTS EFFECTOR ORGANS EFFECT
CONTROL: voluntary, 1 neuron from spinal cord
EFFERENTS: cell body in VENTRAL grey horn or motor cranial nerve nuclei in the brainstem
EFFECTOR ORGANS: Skeletal muscle
EFFECT: excitation
Describe the following features of the autonomic section of the nervous system: CONTROL EFFERENTS EFFECTOR ORGANS EFFECT
CONTROL: involuntary, 2 neurons from brain stem/spinal cord
EFFERENTS: 1st cell body in LATERAL grey horn or motor cranial nerve nuclei in the brainstem, 2nd cell body in peripheral ganglia
EFFECTOR ORGANS: smooth and cardiac muscle; secretory glands
EFFECT: excitation or inhibition
What are the two sections of the autonomic cernous system and what do they cause?
Sympathetic: preparation for emergency
FIGHT OR FLIGHT
Parasympathetic: conserving/ restoring energy
REST AND DIGEST
What is the general layout of Autonomic Pathways?
preganglionic cell body in CNS - lateral horn or brainstem –> preganglionic axon (myelinated) –> Autonomic ganglion –> postganglionic axon (unmyelinated) –> effector organ
Right the generalised structure of a parasympathetic division neuron
Preganglionic neuron –> long preganglionic axon –> autonomic gamglion –> ganglionic neuron –> short postganglionic axon
Right the generalised structure of a sympathetic division neuron
Preganglionic neuron –> Short, branching preganglionic axon –> autonomic ganglion –> ganglionic neuron –> long postganglionic axon
Write the effects of the sympathetic and parasympathetic division on the heart
S - inc. HR, inc. forced contraction, inc. BP
PS - dec. HR, dec. force contraction, dec. Blood pressure
Write the effects of the sympathetic and parasympathetic division on the eye
S - dilate pupil
PS - constrict pupil
Write the effects of the sympathetic and parasympathetic division on the airways
S - inc. airway diameter
PS - dec. airway diameter
Write the effects of the sympathetic and parasympathetic division on the blood vessels
S - dec. GIT blood flow, inc. skeletal muscle blood flow
PS - not innervated
Write the effects of the sympathetic and parasympathetic division on the GIT glands
S - inhibition e.g. dec. insulin production (pancreas)
PS - stimulation e.g. inc. insulin production (pancreas)
Describe the transmission, chemical mediators and distribution effects of direct communication
TRANSMISSION: through gap junctions
CHEMICAL MEDIATORS: ions, small solutes, lipid-soluble materials
EFFECTS: usually limited to adjacent cells of the same type
Describe the transmission, chemical mediators and distribution effects of paracrine communication
TRANSMISSION: through extracellular fluid
CHEMICAL MEDIATORS: paracrine factors
DISTRIBUTION EFFECTS: limited too local area. Target cells must have appropriate receptors
Describe the transmission, chemical mediators and distribution effects of endocrine communication
TRANSMISSION: through the circulatory system
CHEMICAL MEDIATORS: hormones
EFFECTS: target cells are primarily in other tissues and organs and must have appropriate receptors
What are conditions of the chemical mediator being hormones?
they are:
- slower to act (minutes to hours)
- can have multiple targets
- tends to act for longer periods of time as must be removed from blood stream
- sometimes stockpiled in blood on transporter molecules
Describe the transmission, chemical mediators and distribution effects of synaptic communication
TRANSMISSION: across synaptic clefts
CHEMICAL MEDIATORS: neurotransmitters
EFFECTS: limited to very specific areas. target cells must have appropriate receptors
What are the conditions of the chemical mediators being neurotransmitters?
- immediate action
- fast to turn on/off
List the 10 major endocrine organs
- pineal gland
- hypothalamus
- pituitary gland
- thyroid gland
- parathyroid glands
- thymus
- adrenal glands
- pancreas
- ovary
- testis
What two hormones does the posterior pituitary secrete and what do they do?
Antidiuretic hormone (ADH): stimulates kidney to reclaim water from urine, raises blood pressure.
Oxytocin: female reproductive stimulation
Name the seven hormones released by the anterior pituitary gland
- Growth hormone (GH)
- Thyroid stimulating hormone (TSH)
- Prolactin (PRL)
- Adrenocorticotropic hormone (ACTH)
- Melanocyte-stimulating hormone (MSH)
- Follicle-stimulating hormone (FSH)
- Lutenizing hormone (LH)
Where does growth hormone target
- mitosis cells
- liver to produce another hormone
What does thyroid stimulating hormone do?
regulated release of thyroid hormone from the thyroid hormone
describe the adrenal glands
- each adrenal gland is 2 endocrine glands in one
- adrenal medulla is more like a cluster of neurons.
- Secrets adrenalin and noradrenalin
- Adrenal cortex (3 layers) secretes steroid hormones (lipid base): corticosteroids and sex hormones
What does the exocrine (Acinar cells) do?
- for most of the pancreas
- secrete pancreatic juices (digestive enzymes) into the duodenum for digestion
Describe the structure and function of the endocrine (islets of langerhans) in the pancreas
- alpha cells secrete glucagon
- breakdown glycogen into gloucose
- beta cells secrete insulin
- cells take up glucose and storage of glucose as glycogen in the liver
