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Human Biology C8

Human Structure and Function C8

QuestionAnswer
Autonomic The involuntary division of the peripheral nervous system which innervates smooth muscle, cardiac muscle or glands
Axon A nerve fiber extending from the cell body of a neuron
Central Nervous System A subdivision of the nervous system which consists of the brain and spinal cord
Dendrites Cellular projects which extend from the cell body of a neuron
Enteric Referring to the digestive tract
Ion channels A membrane protein channel through which an ion moves
Motor A division of the peripheral nervous system that transmits action potentials from the central nervous system to effector organs e.g. muscles or glands
Myelination The process by which a myelin sheath wraps around an axon
Neuroglial cells Supporting cells of the nervous system
Neuron The basic structural unit of the nervous system
Neurotransmitters A chemical that transmits information from the neuron to its effector cell
Peripheral Nervous system All nervous tissue outside the central nervous system which includes the sensory receptors, nerves, ganglia and plexuses.
Polarised The existence of opposite charges across the cell membrane
Receptors Cell membrane proteins to which a ligand binds
Resting membrane potential The electrical charge difference across the cell membrane in an unstimulated or resting cell
Saltatory conduction The conduction of an action potential from one node of Ranvier to another
Sensory A division of the peripheral nervous system that transmits action potentials from sensory receptors to the central nervous system
Somatic The voluntary division of the peripheral nervous system which innervates skeletal muscle
Synapse A junction between the presynaptic and postsynaptic cells
Vesicles Cytoplasmic organelles that contain neurotransmitters
Voltage gated channel Gated ion channels that open or close when there is a change in membrane potential
What is spinal cord injury? Nerve damage within the spinal canal which disconnects the brain from the spinal cord below the level of injury
What are the consequences of spinal cord injury? Quadriplegia or tetraplegia – partial or complete paralysis and loss of feeling in all four limbs, abdominal and chest muscles Paraplegia – partial or complete paralysis of the lower portion of the body, legs and in some cases the abdomen and chest
What are some of the causes of spinal cord injury in Australia? Trauma from transport-related injuries, falls, sporting activities, diseases (including transverse myelitis, polio, spina bifida, Friedreich’s ataxia, malignant spinal cord compression, etc)
Which demographic (sex and age) do spinal cord injuries most commonly occur in and how are they caused? Males between the ages of 15 - 24 years of age, caused by road trauma or sporting accidents
Function Receive sensory input Description Sensory receptors monitor internal and external stimuli
Function Integrating information Description The CNS processes sensory input and initiates a response. It may be immediate, stored in memory or ignored
Function Controlling muscles and glands Description Skeletal muscles control body movement, smooth muscle can increase or decrease contraction (e.g. to cause vasodilation and constriction), glands – control secretions
Function Maintaining homeostasis Description Cells in the body need to work together to maintain body systems within optimal limits. The nervous system can stimulate or inhibit activities to maintain homeostasis
Function Establishing and maintaining mental activity Description CNS is the centre for mental activities and cognition, keeping us awake or conscious, thinking, emotion, memory, learning etc
What does nervous tissue consists of? Neurons and supporting cells (neuroglia)
What are the components that make up a neuron? dendrites, cell body and axons
What does the Central nervous system consists of? the brain and spinal cord only
What does the peripheral nervous system consists of? all the nervous tissue outside the CNS (nerves, receptors, ganglia, plexuses)
Which of the statements below is true about sensory neurons? transmit information towards the CNS
Which of the statements below is true about motor neurons? transmit information away from the CNS
What is the localised difference in charge across a neuron cell membrane? resting membrane potential
The electrical signals produced by cells are called „action potentials‟. What is their function? Transfer of information from one part of the body to another
What does the term „depolarisation‟ mean? Change in the localised charge difference across the membrane. The RMP becomes more positive (closer to zero). Inside of the cell becomes more positive.
What is a reflex? An automatic respnse to a stimulus, it occurs without conscious thought
What structures does the motor division of (4) innervate? Skeletal muscle
Which division of (1) is responsible for detecting the general and special sensations? Somatic nervous system
Which part of the body is the enteric nervous system concerned with? Digestive tract
Briefly explain the role of sympathetic nervous system? Fight, flight and fright responses i.e. increasing heart rate, respirator rate, direct blood towards muscles and away from non-vital organs
Briefly explain the role of parasympathetic nervous system? Rest and digest processes, reduce heart rate and respiratory rate, stimulate digestion
How does the specialised structure of a neuron reflect its function? As neurons are responsible for transmitting and integrating information, they have many processes (e.g. dendrites, axon) to increase their potential to connect with as many other neurons as possible
Describe the structure and function of the following neuron parts: Cell body Neurons have 1 large cell body that contains the cell nucleus. The cell body also contains many organelles e.g. RER and mitochondria.
Describe the structure and function of the following neuron parts: Dendrites Dendrites are often short and highly branched – they extend out of the cytoplasm of the cell body. Dendrites receive input from the environment and from the axons of other neurons. Dendrites conduct impulses (information) towards the cell body.
Describe the structure and function of the following neuron parts: Axons Neurons (usually) have 1 axon leading away from the cell body. Axons conduct impulses (information) away from the cell body all the way to the presynaptic terminals (e.g. motor neurons go to muscles – neuromuscular junctions). Axons are often myelinated a
Sensory / afferent neurons Conduct impulses (information) towards the CNS
Motor / efferent neurons Conduct impulses (information) away from the CNS towards muscle or glands
The 3 structural classifications of neurons are:  Multipolar - several dendrites and one axon  Bipolar - one dendrite and one axon  Unipolar - one axon split into 2
Which of the neurons are considered: Sensory / afferent neurons? Motor / efferent neurons? Sensory / afferent neurons Unipolar Motor / efferent neurons Multipolar
Where do the axons of these neurons terminate? Sensory / afferent neurons Motor / efferent neurons Sensory / afferent neurons Inside brain (cranial nerves) and spinal cord Motor / efferent neurons Muscle or gland (the effector)
Where are the cell bodies of the following neurons found? Sensory / afferent neurons Motor / efferent neurons Sensory / afferent neurons Taking information towards the CNS. Cell bodies are outside the CNS in dorsal root ganglion Motor / efferent neurons Taking information away from the CNS. Cell bodies are inside brain (cranial nerves) and spinal cord
The majority of neurons (99%) are Interneurons, which integrate information between motor and sensory neurons and lie entirely in the central nervous system.
A reflex in general is a fast, automatic response to a stimulus They are used in posture control / balance, protective responses and in controlling complex but automatic actions like swallowing
Describe the difference between a somatic reflex and an autonomic reflex. Somatic reflexes involve skeletal muscles while autonomic reflexes involve smooth muscles, cardiac muscle or body organs
Membrane potential The immediate inside of the plasma membrane is Negatively Charged
Membrane potential The immediate outside of the membrane is Positively charged
Membrane potential The plasma membrane therefore is: Polarised because there are opposite charges or poles across the membrane. This difference in charge is called the resting membrane potential (RMP).
Indicate on the diagram above the relative numbers of Na+ and K+ leak channels There are more potassium leak channels compared to sodium leak channels.
Which direction do these molecules want to travel (i.e. which direction is their concentration gradient? Na+ ? K+ ? K+ From the inside of the cell to the outside From inside the cell to outside Na+ From outside the cell to inside
Saltatory Conduction occurs in All myelinated axons
Large myelinated axons can conduct impulses at speeds of up to... Large myelinated axons can conduct impulses at speeds of up to 130 metres per second
How are nerve impulses conducted in unmyelinated axons? The reversal of the resting membrane potential has to be generated on each segment of the membrane (depolarisation).
What does this mean in terms of conduction velocity of myelinated versus unmyelinated axons? When myelin is present the RMP is only changed at the Nodes or Ranvier (where there is no myelin) so large segments of the membrane can be skipped, increasing the speed of transmission
Order these... -Vesicles (containing neurotransmitters) move to the presynaptic membrane -Calcium channels open and calcium ions diffuse into the cell and act on vesicles -Action potential arrives at pre-synaptic terminal 1 Action potential arrives at pre-synaptic terminal 2 Calcium channels open and calcium ions diffuse into the cell and act on vesicles 3 Vesicles (containing neurotransmitters) move to the presynaptic membrane
Order these... -Neurotransmitters are released into the synaptic cleft via exocytosis -Neurotransmitters bind to receptors of ion channels on the postsynaptic membrane -Neurotransmitters cross the synaptic cleft 4 Neurotransmitters are released into the synaptic cleft via exocytosis 5 Neurotransmitters cross the synaptic cleft 6 Neurotransmitters bind to receptors of ion channels on the postsynaptic membrane
Order these... -Neurotransmitters removed from synapse by enzyme activity -Ion channels open allowing diffusion of ions in to the postsynaptic cell 7 Ion channels open allowing diffusion of ions in to the postsynaptic cell 8 Neurotransmitters removed from synapse by enzyme activity
Microglial cell Migrate to areas damaged by infection, trauma or stroke and perform phagocytosis
Satellite Cell Provide support and nutrition to neuron cell bodies and protect neurons from heavy metal poisons by absorbing them
Oligodendrocyte Produce myelin which wraps around the axons of several neurons within the CNS
Astrocyte Provide a supportive framework for blood vessels and neurons and regulate the extracellular composition of brain fluid
Ependymal Cell Line the cavities within the brain and contribute to the production of cerebrospinal fluid
Schwann Cell Produce myelin which wraps around the axons of one neuron within the PNS
Created by: KaraaKinetiic