Tissues 8- Cell Signalling 1 Flashcards
Why do cells need to communicate
Process information Sensory stimuli (e.g. sight, sound)- process energy of stimuli into electrical signal that can be interpreted
Self preservation
Identify danger & take appropriate actions
Spinal reflexes
Sympathetic nervous system
Voluntary movement
Getting from A to B
Completing daily tasks
Homeostasis
Thermoregulation
Glucose homeostasis
Why must the human body be able to process information
The human body receives several million inputs from a variety of different sources each day and it must be able to detect these inputs, process the information it receives and manufacture an appropriate response. For example a solitary eyeball or the auditory apparatus within the ears are of little use if they cannot send the data that they receive to a ‘central processing unit’ that can both understand and interpret the information. The majority of the time there is no output information, which is itself of paramount importance, but when an output is required the brain must be able to communicate with a different subset of organs to produce an appropriate response.
Describe self-preservation
The most innate response resulting from an external stimulus is the purpose of self-preservation and this can circumnavigate the brain for speed. The simplest example involved the spinal reflex arc, where the sensory receptors on the periphery detect a painful input ( excessive heat or pin prick) and communicate to the skeletal muscle via the spinal cord resulting in the withdrawal of the affected area from the painful stimulus. However, the painful stimulus may not be associated with a small area of the body and may require the coordinated movement of a number of different organs, i.e fleeing from danger involved communication between the brain and a number of different areas of the body.
Describe voluntary movement
Although movement is occasionally required for the purposes of self-preservation, for the average individual, voluntary movement is mostly required to perform daily tasks such as getting from A to B. The process of voluntary movement involves a complex interplay between a variety of different sensory and motor organs all coordinated by different areas of the brain.
Describe homeostasis
Voluntary movements are not the only reason that an organ such as the brain needs to communicate with other organs. There are numerous involuntary processes that are continuously checked and regulated in order to preserve the cellular environment within the parameters that are required for the body to function properly. It is of vital importance that this homeostasis is maintained and therefore the brain must be able to communicate with all the organs, tissues and cells within the human body. Although the brain acts as a ‘central processing unit’ it does occasionally ‘outsource’ certain tasks that can be overseen by other organs. For example, the parathyroid glands are responsible for regulating Ca2+ levels within the body and the pancreas plays an essential role in regulating blood glucose conc. Therefore it is also important that these lines of communication also exist connecting other organs and tissues within the body.
Describe, briefly, glucose homeostasis in response to hypoglycaemia
Physiological response
Glycogen breakdown (Glycogenolysis)
Gluconeogenesis
Process
Glucagon - secreted by -cells of Islets of Langerhans (in pancreas)
Glucagon - travels out of pancreas in blood vessels
Glucagon - stimulates glycogenolysis & gluconeogenesis within the liver increasing blood glucose levels
What is meant by endocrine signalling
Hormone travels within blood vessels to acts on a distant target cell
List some examples of endocrine signalling
Insulin produced in the pancreas acts on the liver, muscle cells & adipose tissue
Adrenaline produced in the adrenal glands acting on the trachea
Glucagon produced in pancreas and acts on liver
Describe the role of hormones
Hormones are produced by many of the major organs of the body, however there are few organs that play a more prominent role than others (hypothalamus and pituitary).
Hormones act as the message and the recipient is a receptor. Receptors can be located either on the surface of cells as membrane spanning proteins or within the intracellular compartment. The latter type are also available to hormones that have the ability to traverse the cell membrane- membrane permeable hormones.
Describe a method of communication primarily used by cells of the immune system
Receptor-receptor interaction- a perquisite is that one of the participating cells is mobile.
Describe glucose homeostasis in hyperglycaemia
Physiological response Glucose uptake Reduced glycogenolysis Reduced gluconeogenesis Process Increased blood glucose - insulin secretion by - cells in the Islets of Langerhans Insulin has paracrine effects: Inhibiting glucagon secretion Insulin also has endocrine effects on the liver
What is meant by paracrine signalling
Hormone acts on an adjacent cell
List some examples of paracrine signalling
Nitric Oxide produced by endothelial cells in blood vessels
Osteoclast activating factors produced by adjacent osteoblasts
Insulin produced by B cells acting on alpha cells.
Why is insulin acting on a cells described as paracrine as opposed to juxtracrine
Paracrine- same vicinity
Juxtracrine- very adjacent cell
What is meant by signalling between membrane attached proteins
Interaction between membrane proteins of 2 different cells.
