Need To Know For Bio

Front 1

Name and give the functions of the components of a reflex arc

Back 1

Receptor - receives stimulus and triggers a nerve impulseSensory neurone - carries nerve impulses from receptor to CNS .Integrating Centre - regions of Grey matter in CNS where sensory information is processed.motor neurone-carries nerve impulses from CNS to effector .Effector-muscle or glands which respond to motor nerve impulse

Front 2

Draw a fully labelled diagram of a spinal reflex arc and describe it

Back 2

Stimulus makes receptor trigger impulse in sensory neurons which is transmitted to intermediate neurone . intermediate neuron passes that impulse to motor neuron which will transmit impulse to generate a response in the effector .

Front 3

define homeostasis

Back 3

The maintenance of the body's internal environment within narrow physiological limits.

Front 4

define negative feedback

Back 4

The correction of any deviation in the internal environment from a physiological setpoint

Front 5

What are homeostatic mechanisms controlled by

Back 5

Nervous and endocrine system vs feedback loops

Front 6

Describe the effect on output and input of negative and positive feedback

Back 6

negative feedback- output increases, input decreases

positive feedback- as the output increases the input increases

Front 7

give an example of positive feedback

Back 7

Stretch receptors in the cervix cause more contractions of the uterus, which leads to even more stretching of the cervix

Front 8

What is the regulating centre of body temperature ?

Back 8

Hypothalamus-contains receptors that are sensitive to the temperature of blood flowing through it

Front 9

Explain how the system works in low-temperature.

Back 9

When body temperature decreases the thermo-regulating receptor in the hypothalamus detect the change and stimulate heat production mechanisms.

The autonomic nervous system leads to superficial blood vessels to contract to reduce heat loss to air and shivering is intiated increasing aerobic respiration in muscle cells releasing heat.

Thyroid similar cells to increase metabolic heat production and blood flow to the digestive system decreases .

Front 10

Explain how nervous system works when body temperature is high.

Back 10

When the body temperature is high the thermoregulating receptors in the hypothalamus detect the change and initiate heat reducing mechanisms. The autonomic nervous system leads to dilation of superficial blood vessels and sweating is initiated to promote heat loss . Thyroid stimulates cells to decreased metabolic heat production and blood is not diverted from the digestive system.

Front 11

explain the blood glucose regulation

Back 11

When blood glucose levels are high the pancreas detects the change and secrets insulin which stimulates the Liver cells (beta cells) to convert glucose into glycogen for storage and the gluconeogenesis is inhibited in the ER. This decreases the glucose levels to normal.

Blood glucose levels are low the pancreas detects the change and secrets glucagon which stimulates the Liver cells (alpha cells) to convert glycogen into glucose and the gluconeogenesis is stimulated in the ER. Increases the blood glucose levels to normal .

Front 12

How does osmoregulation affect blood pressure?

Back 12

Receptors in the hypothalamus detect the osmolality of blood . When osmolality is high, the blood volume decreases thus decreasing blood pressure, and increases levels of angiotensin II, which stimulates thirst centre in the hypothalamus.

When water levels low blood osmolality increases, which is detected by osmoreceptors in the hypothalamus, which stimulate thursf centre.

Front 13

Describe the Crossed extensor reflex

Back 13

The contraction of extensor muscles in the length opposite of the one that is withdrawn-maintains balance by extending other leg.

Stepping on glass stimulates pain receptors in right foot sensory neurone activates multiple internal neurons. Ipsilateral motor neurons to flexor excited in the flexor contract. While contralateral motor neurons to extensor excited and extensor contract.

Front 14

define neuromuscular Junction

Back 14

The axon terminal of the somatic motor neurone synapses with the skeletal muscle cell.

Front 15

Describe the signal transduction across the neuromuscular Junction.

Back 15

Arrival of an action potential at the axon terminal of the motor neuron causes influx of calcium ions into the motor neurones through membrane of axon terminal. Influx of calcium ions stimulates release of acetylcholine (neurotransmitters) from the axon into the synapse by exocytosis. The acetylcholine diffuses across the synaptic cleft and binds to the sarcolemma, generating muscle action potential which is passed along the sarcolemma, stimulating the release of calcium ions in the sarcoplasma which stimulates muscle fibre contraction.

Front 16

Describe the sliding filament theory of muscle contraction.

Back 16

In contraction calcium ions bind to troponin which releases tropomyosin from the myosin Binding site and calcium binding results in binding site to be revealed on the actin filament. Myosin binds to ATP initially and hydrolysis to ADP making it active. The activated myosin with ADP attached binds to actin filament forming a cross-bridge. Myosin pulls actin inward shortening the sarcomere. Myosin binds to ATP and detaches from actin, ATP converted to ADP and the cycle begins again.

Front 17

Define isometric contractions with an example.

Back 17

Contractions with no change in the muscle fibre length

Maintaining posture, sitting

Front 18

Define isotonic contractions and example

Back 18

Contractions that results in muscle fibre shortening (concentric) or lengthening (eccentric). Walking, lifting an object

Front 19

Describe the two points of muscle attachment.

Back 19

Origin point-point that remains fixed during contractions.

Insertion point-point that moves during contraction.

Front 20

Antagonistic pair of muscles? Give an example. Give an example

Back 20

two muscles that work in opposite directions to achieve movement at a joint. When one muscle contracts the other relaxes.

triceps and biceps

Front 21

Give three adaptations of red blood cells and explain why this is suited to their function .

Back 21

Biconcave shape gives a large surface area to volume ratio ideal for efficient gas exchange

Does not contain cell organelles giving more room in cytoplasm to carry haemoglobin

contains haemoglobin to carry oxygen

Do not contain mitochondria so do not use any oxygen they carry

Front 22

Explain the relationship between resistance and blood pressure and describe two factors that affect it

Back 22

increased resistance increases blood pressure

Blood viscosity of blood is more viscous the higher resistance and so BP

Blood vessel length -the longer the vessel the greater the resistance so higher BP

Blood vessel radius-the smaller of the radius of the higher the resistance and so higher BP

Front 23

describe the conduction system

Back 23

1. the heart contains an area of tissue which demonstrates spontaneous electrical activity which is called the pacemaker or sinoatrial node.

2. Action potential from the SA node spreads through the myocardial cells of the right and left atria causing them to contract.

3. The action potential passes from the atria to the atrioventricular Node which function is to delay the passage of the action potential to give the atria sufficient time to contract.

4. The signal is then passed down the bundle of His which divides into left and right bundle.

5. The signal is conducted up through the ventricles by the purkinje fibres which stimulation causes both ventricles to contract simultaneously.

Front 24

Deceiver how the sympathetic Anna's parasympathetic nervous system controls heat rate

Back 24

CAC in medulla is inverted by the sympathetic nervous system which when stimulated by release of noradrenaline increases heart rate as SA node/ AV node/ myocardium are innervated.

CIC in medulla is innervated by the parasympathetic nervous system which when stimulated by release of acetylcholine decrease the heart rate as SA node/ AV node are inverted.

Front 25

explain the process of expiration

Back 25

the diaphragm and the intercostal muscles relax decreasing the volume of the lungs therefore increasing the pressure and and forcing the air to be moved out down the pressure gradient.

Front 26

explain the process of inspiration

Back 26

diaphragm contracts and pulls down, the intercostal muscles contract lifting ribs up and out. The volume of the lungs increases therefore pressure decreases and air travels in the words down it's pressure gradient from outside.

Front 27

Name the structures involved in the ultrafiltration of the blood in the kidney and describe what structural feature allows ultrafiltration to take place

Back 27

Glomerulus and the Bowman's capsule involved.

The afferent arteriole is a wider than the efferent arteriole which causes an increase in blood pressure in the glomerulus allowing ultrafiltration to take place.

Front 28

describe the osmoregulation in the kidney when water concentration low

Back 28

What water concentration low the osmoreceptors in the hypothalamus detect this change and signals are sent to the pituitary gland increasing secretion of ADH. This causes an increase in the permeability of the kidney tubules and so more water is reabsorbed. This increases water concentration in the blood and produces low volume of concentrated urine.

Front 29

describe the osmoregulation in the kidney when water concentration high

Back 29

When water concentration high the osmoreceptors in the hypothalamus detect the change and signals sent to pituitary gland decrease in secretion of the ADH. This results in kidney removing more water in urine and decrease in water concentration in the blood in result of production of high volume of dilute urine.

Front 30

Give four types of main cells in a gastric glands their secretion and role of secretion

Back 30

Zymogenic cells - pepsinogen - the precursor and inactive form of the protease

Parietal cells - secret HCl - activates pepsin by converting it from pesinogen

- intrinsic factor - required for absorption of vitamin B12

Mucus cells - secrete mucus - prevents digestion of stomach walls

Entroendocrine cells - secrete gastrin -stimulated gastric secretion, increases motility of the stomach

Front 31

How is the small intestine adapted to its role?

Back 31

The inner surface of the small intestine is folded into villi (themselves contain microvilli)to provide large surface area. Each villus contains extremely thin wall for rapid absorption . Each villus contains dance network of blood capillaries and a lacteal to receive the observed food.

Front 32

Describe the cephalic phase of digestion

Back 32

initiated by the smile sight taste or thought of food . Results in stimulation of parasympathetic impulses via the vagus nerve which causes increased gastric secretions and increased gastric motility

Front 33

Describe the gastric phase of digestion

Back 33

Initiated by the stretch receptors and chemoreceptors in the stomach which results in the stimulation of the parasympathetic nervous system leading to waves of peristalsis and secretion of gastric and which stimulates gastric acid secretion and gastric motility