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Flashcards in Movement in the Body Deck (42):

What generates movement in the body

Molecular motors


Describe how a skeletal muscle produces movement of the hand

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


By which method does water move in and out of cells

By passive diffusion through the plasma membrane


What are aquaporins

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


What are 3 uses of molecular motors

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


What are ion channels and pumps

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


What is axoplasmic transport used for

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


Give an example of axoplasmic transport

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


State 3 examples where movement is a part of growth

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


How is growth by movement achieved

By molecular synthesis


How do substances move between cells

1. Intercellular junctions (gap junctions) 2. Synapses


Which two types of cells have gap junctions

Smooth muscle cells and cardiac muscle cells


Give an example of a single cell which can move



How do macrophages defend against the body

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


How many skeletal muscles are there in the human body



Why are there many different types of skeletal muscle

So that they are adapted to their function


What are motor units

The basis of neuromuscular control


Define a motor unit

The skeletal muscle fibres innervated by a single motorneurone


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

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


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

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


How is the tension of a muscle produced

By the shortening of the myofilaments in a sacromere


How is the tension transferred to the bone

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


What is an isotonic contraction

Tension remains constant as the muscle changes in length


What is an isometric contraction

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


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

Isotonic contraction


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

Isometric contraction


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

Striated muscle so contractile mechanism is the same as skeletal muscle


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

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


What unit of time is used to measure skeletal muscle contraction



What unit of time is used to measure smooth muscle contractions



Give examples of smooth muscle contractions

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


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

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


Give examples of the ways smooth muscle cells can be different

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


Why doesn't the bladder burst when its so full

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


What is the volume of an empty human bladder



What is the usual size of a bladder when emptied



What is the maximum capacity of the bladder


How are smooth muscle cells arranged

In layers


What is a major difference between smooth and skeletal muscle cells

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


What is hypertrophy

Increase in cell size


When can smooth muscle cells undergo hypertrophy

In response to pressure


What happens to the the uterus during pressure

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.