BBS1002 Organ systems and Homeostasis
Inhoudsopgave
Case 1: Big tension ........................................................................................................................................... 3
Organization of the nervous system .............................................................................................................. 3
Cells of the nervous system ........................................................................................................................... 4
Membrane potentials ................................................................................................................................... 7
The autonomic nervous system ..................................................................................................................... 9
The symphatic nervous system ................................................................................................................... 11
The parasympathetic nervous system ......................................................................................................... 12
Symptoms of (para)sympathetic nervous system......................................................................................... 13
Case 2: Get to the heart of the matter............................................................................................................ 14
Anatomy of the heart ................................................................................................................................. 14
How does the cardiovascular system work? ................................................................................................ 16
What is the pressure/volume curve? ........................................................................................................... 18
How does the autonomic nervous system affect the cardiac cycle? .............................................................. 19
Explain the figure and table from the case .................................................................................................. 20
Case 3: Blood…. Quo vadis?............................................................................................................................ 21
The anatomy of blood vessels ..................................................................................................................... 21
How do these different blood vessels effect blood pressure ......................................................................... 23
The distribution of blood during exercise and rest ....................................................................................... 26
Case 4: Bigger is better ................................................................................................................................... 27
Lung anatomy ............................................................................................................................................ 27
Breathing cycle ........................................................................................................................................... 29
Neural control of breathing ........................................................................................................................ 30
Lung capacity ............................................................................................................................................. 32
Matching of ventilation and perfusion ........................................................................................................ 33
Case 5: Live low, train high ............................................................................................................................. 35
Solubility of gases....................................................................................................................................... 35
Transport and diffusion of oxygen and carbon dioxide ................................................................................ 36
Breathing frequency regulation .................................................................................................................. 38
Effect of high altitudes on ventilation.......................................................................................................... 39
Case 6: cloaca ................................................................................................................................................. 41
Basic anatomy of the GI tract ..................................................................................................................... 41
, Pathway of digestive tract .......................................................................................................................... 41
Peristalsis (food transportation).................................................................................................................. 43
Enzymes, digestion, secretion ..................................................................................................................... 43
Absorption ................................................................................................................................................. 45
Case 7: Human vs machine ............................................................................................................................. 48
How does the ANS influence the enteric nervous system? And what does the enteric nervous system do?.... 48
How do cells of Cajal function? ................................................................................................................... 50
Hormones and neurotransmitters of the enteric nervous system ................................................................. 50
What are the three phases and describe them. ........................................................................................... 52
Case 8: red but not blue ................................................................................................................................. 57
Anatomy of the urinary tract ...................................................................................................................... 57
Physiology of the urinary tract .................................................................................................................... 63
Filtration of Toxins...................................................................................................................................... 66
Case 9: hot and thirsty ................................................................................................................................... 67
Tubular reabsorption and secretion ............................................................................................................ 67
Regulating blood pressure with the RAAS. ................................................................................................... 69
How does dehydration affect heart rate and respiration............................................................................. 70
How is the concentration of urine regulated? .............................................................................................. 72
Case 10: The delicate balance between acid and base ................................................................................... 76
Buffers in the body ..................................................................................................................................... 76
Acidosis and alkilosis .................................................................................................................................. 81
,Case 1: Big tension
Organization of the nervous system
The nervous system is made up of two parts: the central nervous system
(CNS) and the peripheral nervous system (PNS). The central nervous system
consists of the brain (cerebrum and cerebellum) and the spinal cord. The
peripheral nervous system consists of sensory (afferent) neurons and efferent
neurons. Information flow through the nervous system follows the basic pattern
of a reflex: stimulus - sensor – input signal – integrating center - output signal -
target – response. Efferent neurons subdivide into the somatic motor division,
which controls skeletal muscles, and the autonomic division, which controls
smooth and cardiac muscles, exocrine glands, some endocrine glands, and some
types of adipose tissue.
The autonomic neurons can be broken down into three parts. They can be
distinguished by their anatomical organization and by the chemicals they use to
communicate with their target cells. Many internal organs receive innervation
from both types of autonomic neurons, and it is common for the two divisions to exert
antagonistic control over a single target, which means that if one of the two is active the
other one is inactive. The autonomic nervous system can be divided in:
The symphatic nervous system: The fight or flight response is commonly known, but what
may be lesser known is that this reaction to external stimuli is based completely on the
sympathetic nervous system. When we are faced with a perceived threat of any kind,
whether physical or emotional, our sympathetic nervous system kicks into gear and brings
about automatic and involuntary responses, such as increased heart rate, elevated blood
pressure, heightened awareness, elevated respiratory rate, and more sweating. The
sympathetic nervous system also shuts down many parasympathetic responses in order to
utilize more energy for the fight or flight response.
The parasymphatic nervous system: The parasympathetic nervous system affects the
same body functions as the sympathetic nervous system, but in a completely different way.
It works to slow down certain responses and bring about a state of calm to the body,
allowing it to rest, relax, and repair itself. The primary function of the parasympathetic
nervous system is to maintain long-term health and a healthy balance across all of the
body’s functions. Parasympathetic responses include an increase of digestive enzymes,
decreased heart rate, constriction of bronchial tubes in lungs, and more relaxed muscles.
The enteric nervous system: This system is a network of neurons in the walls of the
digestive tract. It is frequently controlled by the autonomic division of the nervous system,
but it is also able to function autonomously as its own integrating center.
, Cells of the nervous system
This tissue consists of two main type of cells: neurons (nerve cells) and glia. These cells have long,
fine processes.
Neuron classification based on physiology
Unipolar neuron: a neuron that has only a
single extension of the cell body. This
extension divides into two branches,
oriented in opposite directions and
representing the axon. (sensory neurons).
Bipolar neuron: a neuron with only two
extensions—an axon and a dendrite—that
run from opposite sides of the cell body. Cells
of this type are found primarily in the retina
(see retinal bipolar cell) and also elsewhere
in the nervous system. (sensory neurons).
Multipolar neuron: A multipolar neuron is a type of neuron that possesses a single axon and
many dendrites (and dendritic branches), allowing for the integration of a great deal of
information from other neurons. (interneurons of CNS and efferent neurons).
Anaxonic neuron: a type of neuron where there is no axon, or this cannot be differentiated
from the dendrites. (interneurons of CNS)
Neuron classification based on function
There are three types of neurons: sensory (afferent) neurons, interneurons, and efferent
(somatic motor and autonomic) neurons. Sensory neurons carry information about
temperature, pressure, light, and other stimuli from sensory receptors to the CNS. Peripheral
sensory neurons are pseudounipolar, with cell bodies located close to the CNS and very long
processes that extend out to receptors in the limbs and internal organs. In these sensory
neurons, the cell body is out of the direct path of signals passing along the axon. In contrast,
sensory neurons in the nose and eye are much smaller bipolar neurons. Signals that begin at
the dendrites travel through the cell body to the axon. Neurons that lie entirely within the
CNS are known as interneurons (short for interconnecting neurons). They come in a variety
of forms but often have quite complex branching processes that allow them to communicate
with many other neurons. Some interneurons are quite small compared to the model
neuron. Efferent neurons, both somatic motor and autonomic, are generally very similar to
the multipolar neurons. Efferent neurons have enlarged axon terminals. Many autonomic
neurons also have enlarged regions along the axon called varicosities. Both axon terminals
and varicosities store and release
neurotransmitter. The long axons of both afferent
and efferent peripheral neurons are bundled
together with connective tissue into cord- like
fibers called nerves that extend from the CNS to
the targets of the component neurons. Nerves
that carry afferent signals only are called sensory
nerves, and those that carry efferent signals only
are called motor nerves. Nerves that carry signals
in both directions are mixed nerves.
