Movement in the Body

Question 1

What generates movement in the body

Answer 1

Molecular motors

Question 2

Describe how a skeletal muscle produces movement of the hand

Answer 2

1. Cross bridges form between actin and myosin filaments. 2. The relative position of the filaments changes. 3. The sarcomeres shorten. 4. The length of the muscle fibre shortens. 5. The muscle enters a state of contraction. 6. The position of the tendon changes. 7. Movement of the hand follows

Question 3

By which method does water move in and out of cells

Answer 3

By passive diffusion through the plasma membrane

Question 4

What are aquaporins

Answer 4

Intrinsic membrane proteins that form pores in the membranes. Water is actively transported across the plasma membrane through aquaporins.

Question 5

What are 3 uses of molecular motors

Answer 5

1. movement of water in and out of cells 2. Ion channels and pumps 3. Axoplasmic transport

Question 6

What are ion channels and pumps

Answer 6

Complex units made up of sub units. They allow specific ions to enter and exit cells

Question 7

What is axoplasmic transport used for

Answer 7

Moving large molecules, organelles, secretory vesicles and particles around a cell

Question 8

Give an example of axoplasmic transport

Answer 8

1. mRNA moves out of the nucleus into RER 2. Neurotransmitter vesicles travel down the axon

Question 9

State 3 examples where movement is a part of growth

Answer 9

1. Hair 2. Growth and remodelling of the skeleton (changes in size and shape) 3. Growth of neurones in plasticity

Question 10

How is growth by movement achieved

Answer 10

By molecular synthesis

Question 11

How do substances move between cells

Answer 11

1. Intercellular junctions (gap junctions) 2. Synapses

Question 12

Which two types of cells have gap junctions

Answer 12

Smooth muscle cells and cardiac muscle cells

Question 13

Give an example of a single cell which can move

Answer 13

Spermatozoa

Question 14

How do macrophages defend against the body

Answer 14

They move to where they are needed (like microglia in the brain)

Question 15

How many skeletal muscles are there in the human body

Answer 15

500

Question 16

Why are there many different types of skeletal muscle

Answer 16

So that they are adapted to their function

Question 17

What are motor units

Answer 17

The basis of neuromuscular control

Question 18

Define a motor unit

Answer 18

The skeletal muscle fibres innervated by a single motorneurone

Question 19

Describe how the number of muscle fibres in a motor unit depends on the activity that an individual muscle has to perform

Answer 19

Muscles for fine (delicate) movement = small motor units. Muscles for coarse (simple) movements = big motor units

Question 20

There are different types of muscle fibres in the same motor unit- true/false

Answer 20

False- they are all made up of the same fibre e.g. all type 2

Question 21

How is the tension of a muscle produced

Answer 21

By the shortening of the myofilaments in a sacromere

Question 22

How is the tension transferred to the bone

Answer 22

By connective tissues in the muscle and the tendon attaching to the bone

Question 23

What is an isotonic contraction

Answer 23

Tension remains constant as the muscle changes in length

Question 24

What is an isometric contraction

Answer 24

Muscle does not shorten and the tension remains at constant muscle length

Question 25

What type of contraction occurs when muscle tension is sufficient to overcome the weight of an object in your hand, the muscle shortens and you are able to lift the object

Answer 25

Isotonic contraction

Question 26

What type of contraction occurs hen the object of too heavy to lift, the muscle cannot shorten but tension remains

Answer 26

Isometric contraction

Question 27

What type of muscle is cardiac muscle as so what contractile mechanism occurs

Answer 27

Striated muscle so contractile mechanism is the same as skeletal muscle

Question 28

Why are the movements of the heart very different to that of skeletal muscle

Answer 28

They heart acts as a pump and so contractions are aided by valves to ensure blood is pumped only in one direction

Question 29

What unit of time is used to measure skeletal muscle contraction

Answer 29

Milliseconds

Question 30

What unit of time is used to measure smooth muscle contractions

Answer 30

Seconds

Question 31

Give examples of smooth muscle contractions

Answer 31

1. Contraction of blood vessels to assist the circulation. 2. Contraction of GI tract to push ingested food along. 3. Distension of the urinary bladder as it fills, 4. Constriction of the pupil. 5. Contraction of the vans deferens during ejaculation of seminal fluid. 6. Growth and contraction of the uterus during pregnancy and birth. 7. Goose pimples in the skin when cold

Question 32

How is the smooth muscle able to produce such a wide range/ speed/ force of movemenr

Answer 32

Due to the spatial arrangement of the smooth muscle cells and the innervation

Question 33

Give examples of the ways smooth muscle cells can be different

Answer 33

1. In orientation- layers, bundles, rings, helices, meshes. 2. Amount of supporting elements- collagen, elastin fibres. 3. Varied proportions of smooth muscle cells and supporting elements

Question 34

Why doesn't the bladder burst when its so full

Answer 34

The structural relationship between the smooth muscle cells and the extracellular components

Question 35

What is the volume of an empty human bladder

Answer 35

100ml

Question 36

What is the usual size of a bladder when emptied

Answer 36

300-350ml

Question 37

What is the maximum capacity of the bladder

Question 38

How are smooth muscle cells arranged

Answer 38

In layers

Question 39

What is a major difference between smooth and skeletal muscle cells

Answer 39

Skeletal muscle cells are attached to tendons and bones and the contractile force produces by the muscle is transmitted to these skeletal structures to produce movements of the body. Smooth muscles are not attached to any skeletal structures only to other parts of the organs they occur in. The hardening of smooth muscles as they contract acts like a supporting skeleton over which the rest of the muscle can move

Question 40

What is hypertrophy

Answer 40

Increase in cell size

Question 41

When can smooth muscle cells undergo hypertrophy

Answer 41

In response to pressure

Question 42

What happens to the the uterus during pressure

Answer 42

Hypertrophy of the smooth muscle cells in the wall of the uterus. AND hypertrophy of the smooth muscle cells in the uterine artery. After birth everything returns to normal.