1
Q
Homeostasis
A
- maintenance of a stable internal environment
- —> keeps it in a state of dynamic equilibrium (fluctuation around normal level)
- vital for cells to function normally and to stop them being damaged
- temp, glucose, water
2
Q
denatureing of enzymes
A
- enzyme vibrates too much which breaks the hydrogen bonds holding together it 3D structure
- which alters its active site so that it can no longer bind to the substrate or act as a catalyst —> metabolic reactions are less efficient
3
Q
3 things that homeostasis controlls
A
- internal body temperature
- internal glucose concentration
- internal water volume
4
Q
Glucose
A
- cells need constant energy supply so glucose must be controlled
- need around 90mg per 100cm of blood
- monitored by cells in the pancreas
- falls after exercise as more glucose is used in respiration to release energy
5
Q
Water
A
- essential for functioning
- lost during removal of waste products and sweating
- kidneys regulate water content
6
Q
Negative feedback and homeostatic systems
A
- receptors detect when level is too high or low
- info then communicated via the hormonal or nervous systems to the effectors
- effectors counteract the change using negative feedback
- negative feedback: restores the level back to norma
- can only work within limits - if the change is too big it may be to large to counteract
7
Q
positive feedback mechanism
A
- amplify a change from its normal level
- effectors increase level from normal
- e.g. after an injury platelets are activated and release chemicals to activate more platelets ^ conc in the blood but useful bc forms a clot
- NOT INVOLVED IN HOMEOSTASIS - DOESNT MAINTAIN
8
Q
Mechanisms to increase body temp
A
- shivering: muscles contract in spasms - more heat is produced because of more respiration
- less sweat: reduces heat loss
- hair stand-up: trap a layer of air to prevent heat loss
- vasoconstriction: blood vessels near skin constrict so less blood moves through close to surface of skin and releases heat
- Hormones: releases adrenaline and thyroxine - increase metabolism which increases heat production
9
Q
Mechanisms to decrease body temp
A
- sweating: water on the surface of skin evaporates and takes heat from body
- hairs lie flat: less air is trapped so skin is less insulated and can lose heat more easily
- Vasodilation: blood vessels near the surface of the skin widen so more blood flows through them and releases heat energy out of the skin by radiation
10
Q
Hypothalamus and body temperature
A
- maintains body temp at constant level
- receive info about temperature from thermoreceptors which send impulses along sensory neurons to the hypothalamus which send impulses along motor neurons to effectors (SRCER)
- effectors respond and bring body temp back down —> by causing any of the mechanisms that impact body temp
- ‘thermoregulation’
11
Q
Key hole surgery
A
- surgery without making a large incision in the skin
- small incision and insert a tiny camera alongside specialist medical instruments
- less blood, less scarring, less pain and damage done so recover more quickly, easier to return to normal activities and hospital stay is shoerter
12
Q
Protheses
A
- can replace whole limbs e.g. legs
- or parts of limbs e.g. hip joints
- some contain electronic devices that connect to the nervous system so that the limb can operate/move
- make it so disabled people can take part in sports prosthetic legs called blades make it so people without leg(s) can run
- Also make it so that people with certain injuries can play sport again e.g. knee joints
13
Q
anabolic steroids
A
increase strength, speed and stamina by increasing muscle size and allowing athletes to train harder also increasing aggression
14
Q
stimulants
A
- speed up reactions, reduce fatigue, increase aggression
15
Q
Narcotic analgesics
A
- reduce pain, so injuries don’t affect performance
16
Q
FOR Performace-enhancing drugs
A
- up to individuals, have the right to make the decision on whether they’re worth the risk
- drug-free sport isn’t fair anyway different athletes have different access to different trainers, facilities and equipment, drugs can overcome these inequalities
- some people may only be able to reach a higher level through drugs
17
Q
AGAINST performance-enhancing drugs
A
- some are illegal
- unfair people gain advantages without training and hard work
- serious health risks such as high bp and heart problems
- may not be fully informed, taken advantage of by trainers who know better
18
Q
myogenic
A
- it can contract and relax without receiving signals from neurones –> electrical activity allows for regular heartbeats pattern of contractions
19
Q
Heartbeat
A
sino-atrial node (SAN) sends regular waves of electrical activity to the atrial walls to set rhythm of heartbeat
——–>
causes left and right atria to contract at the same time
- non-conducting collagen prevents waves from being passed directly to the ventricles
- instead waves are transferred fromSAN to atrioventrical node (AVN)
- AVN sends electrical wave to bundle of his with a slight delay to make sure the ventricles contract AFTER atria has emptied of blood
- Bundle of his conducts waves to muscle fibres in ventricle walls called purkyne fibres
- purkyne fibres carry electrical wave into walls of both ventricles causing them to contract simultaneously from the bottom up
20
Q
Myogenic
A
SAN—> ATRIA —>.Non-conducting collagen –(not straight to ventricles)–> AVN –(slight delay)–> bundle of his —> Purkyne Fibres –> Ventricles
21
Q
the medulla oblongata and breathing rate
A
- has ventilation centres: inspiratory and expiratory centres –> control rate of breathing
- inspiratory centre sends nerve impulses to the intercostal and diaphragm muscles to make them contract
—> increases volume of the lungs which lowers the pressure of the lungs
- air enters the lungs due to the pressure difference between the lungs and the air outside
- as the lungs inflate stretch receptors are stimulated and send nerve impluses back to teh medulla oblonagata these inhibit the actions of the ispiratory centre
SNAB Biology
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