Question

1 ) Using factors and concepts of protein interactions, describe protein-ligand binding as fully as possible, including the role it plays in the body's physiology, using some of the examples of soluble proteins.

2 ) Describe the structural and functional aspects of a transporting epithelium, including the specific proteins involved that generate the characteristics of this type of epithelium.

3 ) Picture the following fluid replacement therapy: A solution of 0.45% NaCl, 3.3% dextrose (glucose), 100mM urea, and 100mM Albumin (a large protein). Explain the osmolarity & tonicity of this solution as a whole, while also explaining the contribution of each of the four solutes to that overall osmolarity/tonicity. Urea is a true penetrating solute.

4 ) Describe the process of transepithelial transport, including in your description the topics of concentration gradients, polarity of epithelial cells, membrane proteins and membrane transport processes. Describe this from the scenario of an epithelium lining the lumen of an organ.

5 ) Using the classifications of peptide and steroid hormones as laid out in Table 7.1 in the text, contrast these two main classes of hormones with descriptions of their characteristics as laid out in Table 7.1 - some characteristics can be related back to others.

6 ) The hypothalamus and pituitary gland are often involved in the regulation of endocrine glands. Using the information below regarding the hormones involved, fully explain the reflex control pathway, feedback loops, negative feedback (including mechanisms) and the expected symptoms of a hyposecretion pathology.
Hypothalamus - Trophic Hormone H - a modified amine
Pituitary - Trophic Hormone P - a peptide hormone
Endocrine - Hormone E - a steroid hormone which targets lymphocytes (B and T) to inhibit their activity

7 ) Given the following information of a neurotransmitter and the receptors, describe the likely cellular effects seen in two different cell types signalled by this neurotransmitter, including as many of the steps of signal transduction as possible, going as far along the process as possible.
Neurotransmitter: Acetylcholine (ACh)
Receptor displayed by Cell #1 - nicotinic ACh receptor
Receptor displayed by Cell #2 - muscarinic ACh receptor which inhibits adenylyl cyclase (AC)

8 ) Describe the formation and circulation of CSF, taking into account the structural components, membrane transport processes and the importance of the blood-brain barrier capillaries.

9 ) List the functions of the neurons in the midbrain, including those occupying gray matter areas of the substantia nigra, red nucleus and corpora quadrigemina and the white matter areas and those of cranial nerve nuclei.

10) Identify a parallel signalling pathway that delivers information to a location other than the usual sensory pathway. Include the functional description or 'benefit' of the parallel signals, along with the route of the parallel signal. (The 'usual' sensory pathway begins with a sensory receptor cell synapsed with a primary sensory neuron, with the primary sensory neuron delivering the signal into the CNS, synapsing with the secondary sensory neuron, which travels to the thalamus and synapses with the tertiary sensory neuron, which travels to the primary sensory cortex).

Answer 1

8) FORMATION OF CSF

Cerebrospinal fluid is formed by diffusion, pinocytosis and active transport from arterial blood by choroid plexuses of the lateral and 4th ventricle.

Choroid plexus is formed by tufts of capillaries with thin fenestrated endothalial cells.

CIRCULATION

Circulation of csf is with the help of pulsations of choroid plexuses and by the motion of ependymal cells cilia.

It is then absorbed into venous circulation of the body across the arachnoid villi and some of it drains into the lymphatics around the cranial cavity and spinal canal.