WEEK 1: Homeostatsis

Question 1

What is homeostasis?

Answer 1

The body’s ability to detect the change, activate mechanisms that oppose it and maintain relatively stable internal conditions.

Question 2

How is homeostasis maintained?

Answer 2

2 ways:

1. NS (electrial -fast acting)
2. Endocrine system (chemical - hormones that produce long lasting changes).

Question 3

Elements of a feeback loop.

Answer 3

STIMULUS = produces a change in variable i.e., eating a sandwich (temp) or sandwich (blood glucose).

RECEPTOR = detects change caused by the stimulus.

INPUT = information to control centre along the afferent pathway (a= arrives).

CONTROL CENTER = integrates information to determine a response (e=exits).

EFFECTOR = responds to reduce the effect of stimulus i.e., motor neuron causes bicep to contract so that person can drink water to rehydrate.

Question 4

What is a negative feedback loop?

Answer 4

THE PRODUCT OF A REACTION LEADS TO A DECREASE IN THAT REACTION

A change is detected by a receptor and an effector is activated to induce an opposite effect. Promotes equilibrium.

i.e., temperatue regulation - body temperature increases which signals the body to sweat which decreases body temperature. Then a body temp decrease, signals shivering which works to increase temperature.

Question 5

What is a positive feedback loop?

Answer 5

A process in which the end products of an action cause more of that action to occur.

i.e., blood clotting at the site of an injury. Platelets are sent ot the site of injury and they trigger chemicals that signal even more platelets which signal even more chemicals!

i.e., childbirth: head of the foetus pushes on cervix, nerve impulses from cervix transmitted to the brain, the brain stimulates pituitary gland to secrete oxytocin, oxytocin stimulates uterine contractions and pushes foetus toward the cervix.

Question 6

Relationship between homeostatic imblance and disease.

Answer 6

Most diseases caused by disturbance to homeostasis.
- aging
- genetic mutations
- pathogens
- envionrmental factors

Question 7

Aging - cause of disturbance to homeostasis.

Answer 7

1. Aging: our receptors come less sensitive and the ability of our effectors to reverse changes diminishes

i.e., we can’t detect water in the blood, we aren’t aware we are dehydrated and so we don’t drink, then effectors can’t make us drink water. We have to use different methods then alike hormones that reabsorb more water in kidneys and we release less of these with time and so our kidneys are less efficient and so dehydration becomes an issue.

Question 8

Genetic mutations - cause of disturbance to homeostasis.

Answer 8

2. Genetic mutations: cancers, tumours cause our body to work less efficiently.

Question 9

Pathogens - cause of disturbance to homeostasis.

Answer 9

3. Pathogens: viruses, fungi, bacteria

Question 10

Environmental factors - cause of disturbance to homeostasis.

Answer 10

4. Environmental factors: heat or cold, stress i.e., cortisol can alter us negatively.